NCERT 9th

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English NCERT 9TH

MATH-9TH

SCIENCE 9TH

DESCRIBING MOTION

FORCE AND LAWS OF MOTION

WORK POWER AND ENERGY

GRAVITATION

Gravity: The gravitational force exerted by the earth on an object is known as gravity, or the force  with which the huge heavenly body (e,g earth) pulls the objects towards its centre  is known as gravity or gravitational force of earth.

Gravitation: The force which pulls the objects  towards each other in the universe is called as gravitation. All objects in this universe attract each other with a force along the line joining their centres which is called as gravitation.

Historical Perspective:-

In the time of Aristotle, it was believed that an apple (or any object) release from a height would fall down towards earth because it was natural for any object to fall down towards earth because it was natural for any object to fall down towards earth . It was thought that this fact needs no explanation because it was natural. Galileo in the 16^th century suggested that since earth is attracting objects towards itself, therefore ,objects fall down towards earth.

As Great minds not only think logically but have the capacity to extend a simple idea to other related phenomenon .Newton’s greatness lies in his ability to see that the force responsible to attract apple towards earth was the same force of attraction that operated between earth  and moon or  between sun and planets .Not only this, he expended the idea further to include within its purview all material objects.

 

 

FLOATATION

SOUND

MATTER IN OUR SURROUNDING

TOPIC :-MATTER IN OUR SURRONDINGS

CLASS:- 9^TH                                                                         

Introduction

• Anything which occupies space and has mass is called matter. Air and water, sugar and sand, hydrogen and oxygen etc.
• Ancient Indian philosophers said that all the matter, living or non-living was made up of five basic elements (panch tatva): air, earth, fire, sky and water.
• Modern day scientists classify matter in two ways: on the basis of its physical properties and on the basis of its chemical properties.
• On the basis of physical properties, matter is classified as solids, liquids and gases.
• On the basis of chemical properties, matter is classified as elements, compounds and mixtures.

Physical nature of matter

• Matter is made up of particles.
• Everything around us is made up of tiny pieces or particles. The particles of matter are constantly moving (they are in motion).
• The particles which make up matter are atoms and molecules.

Evidence of particles in matter:

• The evidence for the existence of particles in matter and their motion comes from the experiments on diffusion and Brownian motion.

Dissolving a solid in a liquid:

• When a crystal of potassium permanganate is placed in a beaker of water, the water slowly turns purple on its own, even without stirring.
• Both potassium permanganate crystal and water are made up of tiny particles.
• When the potassium permanganate crystal is put in water, its particles separate from one another.
• These purpled colored particles of potassium permanganate spread throughout water making the whole water look purple.
• Actually, on dissolving, the particles of potassium permanganate get into the spaces between the particles of water.
• So it is concluded that the particles are moving or they are in motion.

Mixing of two gases:

• Air is a colorless gas. Bromine vapor is red-brown in color, and it is heavier than air.
• A gas jar containing air is placed upside down on a gas jar of bromine vapor.
• We will see that the red brown vapors of bromine from the lower gas jar spread up into air in the upper gas jar. And after some time, the gas jar containing air also becomes completely red-brown in color.
• Both air and bromine vapors are made of tiny moving particles. The moving particles of bromine collide with each other and bounce about in all directions, due to which they get mixed uniformly. This is another example of diffusion.

The process if diffusion gives us two conclusions about the nature of matter.

1.    The matter is made up of tiny particles.

2.    The particles of matter are constantly moving.

Movement of pollen grains in water:

• The best evidence for the existence and movement of particles in liquids was given by Robert Brown in 1827. Robert Brown suspended extremely small pollen grains in water.
• It was found that the pollen grains were moving rapidly throughout water in a very irregular way.
• Water is made up of tiny particles which are moving very fast. The pollen grains move on the surface of water because they are constantly being hit by the fast moving particles of water.
• The zigzag movement of the small particles suspended in a liquid (or gas) is called Brownian motion.

The existence of Brownian motion gives us two conclusions about the nature of matter.

1.    The matter is made up of tiny particles.

2.    The particles of matter are constantly moving.

Characteristics of particles of Matter:

The important characteristics of particles of matter are the following:

1.    The particles of matter are very, very small.

2.    The particles of matter have space between them.

3.    The particles of matter are constantly moving.

4.    The particles of matter attract each other.

The particles of matter are very, very small:

The very, very small size of particles of matter can be shown by performing the following experiment by using potassium permanganate and water.

• Take 2-3 crystals of potassium permanganate and dissolve them in 100 ml of water in a beaker. We will get a deep purple colored solution of potassium permanganate in water.
• Take out approximately 10 ml of this solution and put it into 90 ml of clear water in second beaker. Due to this dilution, the color of potassium permanganate solution in the second beaker becomes a bit lighter.
• Take out 10 ml of this solution and put it into another 90 ml of clear water in third beaker. The color of solution will become still lighter.
• Keep diluting the solution like this 5 to 8 times.
• In this way, we get a very dilute solution of potassium permanganate in water but the water is still colored.
• This experiment shows that just a few crystals of potassium permanganate can colour a large volume of water.
• So we conclude that there must be millions of tiny particles in just one crystal of potassium permanganate, which keep on dividing themselves into smaller and smaller particles.

The particles of matter have space between them:

The spaces between the particles of matter can be shown by performing the following experiment by using water and sugar.

• Take a 100 ml beaker.
• Fill half the beaker with water and mark the level of water.
• Dissolve some sugar (50gm) with the help of a glass rod.
• We will find that the level of sugar solution in the beaker is at the same mark where water level was initially in the beaker.
• When sugar is dissolved in water, its crystals separate into very fine particles. These particles of sugar go into the spaces between the various particles of water due to which there is no change in the volume of water on dissolving sugar in it.
• The fact that there is no change in volume on dissolving sugar in water tells us that there are spaces between the particles of water. 

The particles of matter are constantly moving:

• The best evidence that particles of matter are constantly moving comes from the experiments on diffusion and Brownian motion.
• The particles of matter are constantly moving can be shown by performing the following experiment by using potassium permanganate and water.
• As in above.
  If we carry out this experiment by using hot water in the beaker (or gas jar), we will find that the water turns purple at a faster rate. This is because, on heating, the particles of water and that off potassium permanganate gain kinetic energy and move faster. And due to faster movements, they mix into each other more quickly.

The particles of matter attract each other:

• There are some forces of attraction between the particles of matter which bind them together.
• The force of attraction between the particles of the same substance is known as cohesion.
• If we take a piece of chalk, a cube of ice and an iron nail, and beat them with a hammer, we will find that it is very easy to break the piece of chalk into smaller particles, it requires more force to break a cube of ice, whereas the iron nail does not break at all even with a large force.
• This shows that the force of attraction between the particles of chalk is quite weak; the force of attraction between the particles of ice is a bit stronger whereas the force of attraction between the particles of iron nail is very, very strong.

Note:  In general, the force of attraction is maximum in the particles of solids matter and minimum in the particles of a gaseous matter.
Note: rigid means ‘unbending’ or ‘inflexible’. A stone is rigid because it is unbending or inflexible.
Fluid means a material which can flow easily and requires a vessel to keep it.                                                  States of matter:

On the basis of physical state, all the matter can be classified into three groups: Solids, Liquids and Gases.

 

Properties of Solids, Liquids and Gases:

S.No.	Solids	Liquids	Gases
1.	Solids have a fixed shape and fixed volume	Liquids have fixed volume but they have no fixed shape	Gases have neither a fixed shape nor a fixed volume
2.	Solids cannot be compressed much	Liquids cannot be compressed much	Gases can be compressed easily
3.	Solids have high densities	Liquids have moderate to high densities	Gases have very low densities
4.	Solids do not fill their container completely	Liquids do not fill their container completely	Gases fill their container completely
5.	Solids do not flow	Liquids generally flow easily	Gases flow easily
6.	For example: Ice, coal, wood, stone, iron, etc.	Water, milk, fruit juice, ink, petrol, etc.	Air, oxygen, hydrogen, nitrogen, steam, etc.

 

Why Solids, Liquids and Gases have different properties:

• According to the kinetic theory of matter, the particles of matter are in continuous motion and possess kinetic energy.
• Some forces of attraction also exist between the particles of matter. These are called inter particle forces. The forces of attraction tend to hold the particles together and control their movements.

The following properties of particles decide whether a given substance will exist as a solid, a liquid or a gas:

1.    The spaces between the particles: the spaces between the particles are the minimum in solids, a little more in liquids, and the maximum in gases.

2.    The force of attraction between particles: the forces of attraction between the particles are the strongest in solids, less strong in liquids and negligible in gases.

3.    The amount of movement of particles (or kinetic energy of particles): the movement of particles is the minimum in solids, more in liquids and the maximum in gases.

Diffusion:

• The spreading out and mixing of a substance with another substance due to the motion of its particles is called diffusion.
• The diffusion of one substance into another substance goes on until a uniform mixture is formed. For example: diffusion of bromine vapors in air. 
• Diffusion is the property of matter which is based on the motion of its particles. Diffusion occurs in gases, liquids and solids.
• Diffusion is fastest in gases and slowest in solids.
• The rate of diffusion increases on increasing the temperature of the diffusing substance.

Diffusion in Gases:

• Diffusion in gases is very fast. This is because the particles in gases move very quickly in all directions.
• The rate of diffusion of a gas, however, depends on its density. Light gases diffuse faster than heavy gases.
• Example: When we light an incense stick (agarbatti) in a corner of our room, its fragrance spreads in the whole room very quickly due to the diffusion of its smoke into the air.

Diffusion in liquids:

• Diffusion in liquids is slower than that in gases. This is because the particles in liquids move slowly as compared to the particles in gases.
• Example: The spreading of purple colour of potassium permanganate into water, on its own, is due to the diffusion of potassium permanganate particles into water.
• Note: The gases like carbon dioxide and oxygen are essential for the survival of aquatic plants and animals. The carbon dioxide and oxygen gas present in air diffuse into water, and dissolve in it. The aquatic plants use the dissolved carbon dioxide for preparing food by photosynthesis and aquatic animals use the dissolved oxygen of water for breathing. This is an example of diffusion of gases into a liquid.

Diffusion in solids:

• Diffusion can also takes place in solids. Diffusion in solids is very, very slow process.
• Example: If we write something on a blackboard and leave it uncleaned for a considerable period of time, we will find that it becomes quite difficult to clean the blackboard afterwards. This is due to the fact that some of the particles of chalk have diffused into the surface of blackboard.

The Common Unit of Temperature and SI Unit of Temperature:

• The common unit of measuring temperatures (like melting points, boiling points etc.) is ‘degrees Celsius’ which is written in short form as °C.
• Laboratory thermometers and clinical thermometer are calibrated on Celsius scale of temperature.
• There is another scale of temperature called Kelvin scale of temperature which is used by the scientists mainly for research work. The SI unit of measuring temperature is Kelvin, which is denoted by the symbol K.
• The relation between Kelvin scale and Celsius scale of temperature can be written as:

                             Temp. on Kelvin scale=Temp. on Celsius scale + 273

1.    To convert a temperature on Celsius scale to Kelvin scale, we have to add 273 to the Celsius temperature.

2.    And to convert a temperature on Kelvin scale to the Celsius scale, we have to subtract 273 from the Kelvin temperature.                                                                                                                       

 

Change of State of Matter:

• We can change the physical state of matter in two ways:

1.    By changing the temperature (heating or cooling).

2.    By changing the pressure (increasing or decreasing the pressure).

• These two factors decide whether a given substance would be in a solid, liquid or gaseous state.

Effect of Change of Temperature:                                                                                           

Solid to Liquid Change: Melting

• The process in which a solid substance changes into a liquid on heating,is called on melting or fusion.
• The temperature at which a solid substance melts and changes into a liquid at atmospheric  pressure, is called melting point of substance. For example, the ice melts at a temperature of 0°C to form liquid water, so the melting point of ice is 0°C (zero degree Celsius). At melting point, ice changes its state from solid to liquid.
• Different solids have different melting points. Higher the melting point of a solid substance, greater will be the force of attraction between its particles.
• The melting point of a solid is an indication of the strength of the force of attraction between its particles.
• When a solid substance is heated, the heat energy makes its particles vibrate more vigorously. At the melting point, the particles of a solid have sufficient kinetic energy to overcome the strong forces of attraction holding them in fixed positions and break to form small groups of particles and the solid melts to form a liquid.

Liquid to Gas Change: Boiling (or Vaporisation):

• The process in which a liquid substance changes into a gas rapidly on heating, is called boiling.
• The temperature, at which a liquid boils and changes rapidly into a gas at atmospheric pressure, is called boiling point of the liquid.
• For example, when water is heated to a temperature of 100 °C (hundred degree Celsius).
• Different liquids have different boiling points.
• The boiling point of a liquid is a measure of the force of attraction between its particles.
• When a liquid is heated, the heat energy makes its particles move even faster. At the boiling point the particles of liquid have sufficient kinetic energy to overcome the forces of attraction holding them together and separate into individual particles. And the liquid boils to form a gas. 

Gas to Liquid Change: Condensation

• The process of changing a gas (or vapour) to a liquid by cooling is called condensation.
• When steam (or water vapour) changes into water on cooling, it is called condensation of steam.
• When a gas is cooled enough, then its particles lose so much kinetic energy that they slow down, move closer together until they start being attracted to each other, and form a liquid.

Liquid to solid change: Freezing

• The process of changing a liquid into a solid by cooling is called freezing.
• For example, when water is cooled, it gets converted into a solid called ‘ice’. This is called freezing of water. Freezing means solidification.

Latent heat:

• The heat energy which has to be supplied to change the state of a substance is called its latent heat.
• Latent heat does not raise (or increase) the temperature. But latent heat has always to be supplied to change the state of a substance .The word ‘latent’ means ‘hidden’.
• The latent heat which we supply is used up in overcoming the forces of attraction between the particles of substance during the change of state. Latent heat does not increase the kinetic energy of the particles of the substance, so the temperature of a substance does not rise during the change of state.

Latent heat is of two types:

1.     Latent heat of fusion

2.     Latent heat of vaporization.

Latent Heat of Fusion (solid to liquid change):

• The heat which is going into ice but not increasing its temperature, is the energy required to change the state of ice from solid to liquid (water). This is known as the latent heat of fusion of ice (or latent heat of melting of ice).
• The latent heat  of fusion (or melting) of a solid is the quantity of heat in joules required to convert 1 kilogram of the solid (at its melting point) to liquid, without any change in temperature.
• The latent heat of fusion of ice is 3.34×10⁵ joules per kilogram (or 3.34 ×10⁵ j/kg).

Latent Heat of Vaporization (liquid to gas change):

The latent heat of vaporisation of a liquid is the quantity of heat in joules required to convert 1 kilogram of the liquid (at its boiling point) to vapour or gas, without any change in temperature.
The latent heat of vaporization of water is 22.5×10⁵ joules per kilogram (or 22.5×10⁵ j/kg).
Note: It has been found that the burns caused by steam are much more severe than those caused by boiling water though both of them are at the same temperature of 100 °C. This is due to the fact that steam contains more heat, in the form of latent heat, than boiling water.

Sublimation:

The changing of a solid directly into vapours on heating and of vapours into solid on cooling, is known as sublimation.

1.    The changing of a solid directly into vapor (or gas) is called sublimation.

2.    The changing of vapor (or gas) directly into solid is called sublimation.

• The common substances which undergo sublimation are: Ammonium chloride, Iodine, Camphor, Naphthalene and Anthracene.
• When these solids are heated, their particles move so quickly that they separate completely to form vapor (or gas). And when these vapor (or gas) is cooled, these particles slow down so quickly that they become fixed and form a solid.

Effect of Change of Pressure:                                                                            

 The physical state of matter can also be changed by increasing the pressure or decreasing the pressure.

• Gases can be liquefied by applying pressure and lowering temperature
• When a high pressure is applied to a gas, it gets compressed (into a small volume), and when we also lower its temperature, it gets liquefied. So, we can also say that gases can be liquefied (turned into liquids) by compression and cooling.
• Ammonia gas can be liquefied by applying high pressure and lowering the temperature.
• Decreasing the pressure and raising the temperature can change the state of matter.
• Solid carbon dioxide (dry ice) is stored under high pressure. When a slab of solid carbon dioxide is kept exposed to air, then the pressure on it is reduced to normal atmospheric pressure (1 atmosphere), its temperature rises, and its starts changing into carbon dioxide gas.

Evaporation:                                                                                                                                           The process of a liquid changing into vapour (or gas) even its boiling point is called evaporation.

• The wet clothes dry due to evaporation of water present in them. Common salt is also recovered from sea-water by the process of evaporation.
• The process of evaporation can be explained as follows: Some particles in liquid always have more kinetic energy than the others. So, even when a liquid is well below its boiling point, some of its particles have enough energy to break the forces of attraction between the particles and escape from the surface of the liquid in the form of vapour (or gas). Thus the fast moving particles (or molecules) of a liquid are constantly escaping from the liquid to form vapor (or gas).

Factors affecting Evaporation:

The evaporation of a liquid depends mainly on the following factors:

1.    Temperature

2.    Surface area

3.    Humidity

4.    Wind speed

1.    Temperature: The rate of evaporation increases on increasing the temperature of the liquid.

2.    Surface area of the liquid: The rate of evaporation increases on increasing the surface area of the liquid. For e.g. If the same liquid is kept in a test tube and in a china dish, then the liquid kept in the china dish evaporate more rapidly.

3.    Humidity of Air: The amount of water present in air is represented by a term called humidity. When the humidity of air is slow, then the rate of evaporation is high, and water evaporates more readily.

4.    Wind Speed: The rate of evaporation of a liquid increases with increasing wind speed.

Cooling caused by evaporation:

• The cooling caused by evaporation is based on the fact that when a liquid evaporates, it draws or takes the latent heat of vaporization from ‘anything’ which it touches. By losing heat, this ‘anything’ gets cooled.

• During hot summer days, water is usually kept in an earthen pot (called pitcher or matka) to keep it cool. The earthen pot has large number of extremely small pores (or holes) in its walls. Some of the water continuously keeps seeping through these pores to the outside of the pot. This water evaporates (changes into vapor) continuously and takes the latent heat required for vaporization from the earthen pot and the remaining water. In this way, the remaining water loses heat and gets cooled.
• Perspiration (or sweating) is our body’s method of maintaining a constant temperature.
• We should wear cotton clothes in hot summer days to keep cool and comfortable.

To Show the Presence of Water Vapour in Air:

• There is always some water vapor in the air around us. Water vapor comes into the air from the evaporation of water present in ponds, lakes, rivers and oceans.
• Water vapor is also given out by plants by the process of transpiration. Animals give out water vapor when they breathe out air. All this water vapor goes into the air around us.
•  

 

The presence of water vapor in air can be shown by the following experiment:

• Let us take some ice -cold water in a tumbler. Soon we will see water droplets on the outer surface of tumbler. The water vapor present in air, on coming in contact with the cold glass of water, loses energy and gets converted to liquid state, which we see as water droplets.

Plasma & Bose- Einstein Condensate:

Plasma and Bose- Einstein Condensate are two more states of mater apart from three other discussed previously.
Scientists now say that there are actually five states of matter: Solid, Liquid, Gas, Plasma and Bose- Einstein Condensate.

Plasma:-

• Plasma is a mixture of free electrons and ions. Plasma occurs naturally in the stars (including the sun).
• Inside the stars, the temperature is so high that the atoms break up. Some of the electrons break away from the atoms converting the rest of atoms into electrically charged particles called ions. This mixture of free electrons and ions in a star is called plasma.

• The sun and other stars glow because of the presence of plasma in them.
• Plasma can also be made on the earth by passing electricity through gases at very low pressure taking in a glass tube. The fluorescent tubes and neon sign bulbs form plasma when they are switched on.

Bose- Einstein Condensate:-

• In 1920 Indian physicist Satyendra Nath Bose had done some calculations for a fifth state of matter. Building on it calculations, Albert Einstein predicted a new state of matter- the Bose Einstein Condensate (BEC).
• The BEC is formed by cooling a gas of extremely low density (about one –hundred- thousandth the density of normal air) to super low temperature.

 

 

 

 

                   

 

 

                    TEXTUAL QUESTIONS

Q NO 1:-Which of the following are matters? Chair, air, Love, Hate, Almonds,   

           Thought,  Cold, Drink & Smell of perfume.

ANS:-Any thing which occupies space and have mass is called matter. Therefore Chair, 

          Air, Smell, Almonds, Cold drink and smell of perfume are matter.

Q NO 2:-Give reasons for the following observations. The smell of hot sizzling food 

           reaches you several meters away, but to get smell from the cold food you have

           to close?

ANS:-The particles of matter possess kinetic energy and thus are constantly moving at low temperatures, the kinetic energy is low and hence the particles move slowly. But as the temperature rises, the kinetic energy increases accordingly and hence the particles move faster. Now since the particles of hot vapour’s coming out of the hot sizzling food moves faster, therefore they easily reach to us even when we are several meters away. On the other hand, the particles of vapour’s coming out of cold food travel slowly and hence don’t reach to us. Therefore, to get the smell we have to go close.

 

Q NO 3:-A Diver is able to cut through water in a swimming pool. Which property of matter does this observation show?

ANS:-This property shows the force of attraction with which the particles of water are held together.

 

Q NO 4:-What are the characteristics of particles of matter?

ANS:-Some of the characteristics of particles of matter are:-

1.     Matter consists of tiny particles, which can’t be seen with the naked eye.

2.     There exists space between the particles of matter.

3.     The particles of matter are continuously moving.

4.     The particles of matter are hold together by force of attraction.

 

Q NO 5:-Difference between Solids, Liquids and Gases?

SOLIDS	LIQUIDS	GASSES
Particles are closely packed	Particles are less closely packed	Particles are free each other
Inter particle distances are small	Inter particle distances are larger	Inter particle distances are  largest
They have definite shape and volume	They have definite volume but no definite shape	They have no definite shape nor volume
They are incompressible	They are almost incompressible	They are highly compressible
They posses rigidity	They can flow  therefore they posses fluidity	They flow more easily thus have the highest fluidity
They have high density	There density is lower than those of solids	They generally have low density
Inter particle forces of attraction are stronger	Inter particle forces of attraction are weaker	Inter particle forces of attraction are the weakest

 

1.RIGIDITY:-means  tendency to maintain shape when some outside force is applied.Due to small inter particle distance and strong inter particle force of attraction solids passes height rigidity.

2.COMPRESSIBLITY:-Means to decrease volume  when same out side force isn applied.

3.FLUIDITY:-Means the  tendency to flow. Due to large inter particle distance and weak force of attraction gasses have the highest fluidity.liquids also have a tendency to flow.

4.DENSITY:-Means the mass per unit volume.solids have highest density than liquids and gasses.

5.KINETIC ENERGY:-Means the energy possessed by virtue of motion. Gasses  have highest kinetic energy.

 

Q NO 7:-Liquids generally have lower density as compared to solids ,but you must have observed that ice floats on water.find out why?

ANS:-When ice freezes to form ice, some empty spaces are created. As a result , volume increases and we know that density of ice is lower than that of water and hence ice floats our water.

 

Q NO 8:-Convert the following temperatures of the celcius scale:

(a)300K            (b)573K

ANS:-The temperature on the Kelvin scale can be converted into celcius by subtracting 273 from the temperature on  the Kelvin scale. Thus

(a)300K  = 300 – 273 =27 degree celcius.

(b)573K = 573 – 273 = 300 degree celcius.

 

Q NO 9:-What is the physical state of water at:

(a)250 degee celcius

(b)100 degree celcius

ANS:-(a):The boiling point of water is 100 degree celcius. Therefore, the physical state  of water at 250 degree celcius ,i.e , at a temperature higher than its boiling point is gaseous state.

           (b):At 100 degree celcius , the boiling point of water, water exists both as liquid as well as gas.

 

Q NO 10:-For any substance, why does the temperature remain constant during  the change of state?

ANS:-During the change of state of a substance as its melting point or the boiling point,temperature remains constant   because the heat energy supplied to the substance is used up in breaking the forces of attraction between the particles of  a substance. That is why there is not any raise in temperature the entire substance undergoes change of state.

 

Q NO 11:-Suggest a method to liquefy atmospheric gasses?

ANS:-Atmospheric gasses can be liquefied by increasing the forces of attraction between  the constituent particles. This can be done by cooling the gasses under high pressure.

 

Q NO 12:-Why does a desert cooler cool better on a hot dry day?

ANS:-A hot dry day means that temperature of the atmosphere is high and humidity of air is low. Both these factors increase the rate of evopration and thus more cooling is produced.

 

Q NO 13:-How does the water kept in an earthen pot (Matka) becomes cool during  summer?

ANS:-Due to the small holes present in the walls of the earthen pot, the water oozes or comes out from these small holes slowly. As it comes on the outer surface of earthen pot, it evoprates. The energy needed for evopration is taken from the water kept in the earthen pot. As a result, water kept in the earthen pot becomes cool.

 

Q NO 14:-Why does our palm feel cold when we put some acetone or perfume on it?

ANS:- When  Acetone, petrol or perfume are put on the palm, they quickly evaporate. The energy needed for evaporation is taken from the palm as a result, the palm feels cold.

 

Q NO 15:-Why are we able to sip hot tea or milk faster from a saucer rather than a cup?

ANS:-When hot tea or milk is taken in a cup, the surface area of the liquid in the cup is small. Therefore, evaporation  occurs slowly and hence  the liquid in the cup remain hot for a  long time & we are not able to sip hot tea or milk from a cup. However, when hot tea or milk is placed in a saucer , the surface area of the liquid increases in a saucer. As a result, evaporation occurs faster and the tea or milk becomes little cooler more quickly. In other words, we are able to sip hot tea or milk faster from a saucer rather than from a cup.

 

Q NO 16:-What type of clothes should we wear in summer?

ANS:-In summer we perspire more. Therefore ,to keep our body cool, we must wear cotton clothes. Since cotton clothes are good absorber of water, they absorb the sweat quickly and expose it to the atmosphere for easy evaporation, since evaporation produced cooling, therefore, cotton clothes help us in keeping our body cool.

 

Q NO 17:-Give reasons of the following:

(a)A  gas fills completely the vessel in which it is kept.

(b)A gas exerts pressure on the walls of the container.

(c)A wooden table should be called a solid.

ANS:-(a) The particles of a gas are constantly moving in all the directions with different speeds. Therefore they don’t have fixed volume and hence completely fill the vessel in which they are kept.

(b) The particles of gas show random motion due to which they collide with each other and also  against the walls of the container and as a result of there collusions they exert pressure on the walls of the container, which is also called pressure of the gas.

(c)  A wooden table has a definite shape, distinct boundaries and a fixed volume. Therefore, it should be called solid.

 

 

 

MATTER AROUND US PURE

ATOMS AND MOLECULES

STRUCTURE OF ATOM

THE FUNDAMENTAL UNIT OF LIFE

TISSUES

TOPIC :- TISSUE             (BIOLOGY)

 

TISSUE:-Tissue can be defined as a group of cells of similar shape ,size , function and have a common origin. Study of tissue is called Histology.

                               PLANT TISSUE

The higher plants have multicellular bodies made up of various kinds of cells. These cells cluster together to perform pacific functions. These group of cells are called tissues. The plant tissue is classified into two main groups.

(1). MERISTEMATIC  TISSUE:-

(2). PERMANENT  TISSUE:-

(1). MERISTEMATIC TISSUE:- Meristematic tissue is group of immature cells that has capacity of division and redivision.

The term meristem was coined by Nageli (1858). Meristemsin plants are found in apex of stem, root, leaf primordia, vascular cambium, cork cambium, etc.

 

Characteristics of Meristematic Tissue:

1. They are composed of immature cells.

2. Absence of intercellular spaces.

3. Cells are oval, rounded or polygonal in shape.

4. Cells are always living and thin walled.

5. Cells are rich in cytoplasm with minute vacuoles.

6. Cell is diploid and shows mitotic cell division.

7. Cell is devoid of reserve food materials, ER and plastids.

Functions of Meristematic Tissue:

1. Meristems are actively dividing tissues of the plant.

2. They are responsible for primary (elongation) and secondary (thickness) growth of the plant.

3. All new organs and their growth occur by the division of meristematic tissue.

4. Secondary tissues such as, wood, cork are also formed due to activity of meristematic tissue.

On the basis of location  Meristematic tissue is of three types:

(A). Apical meristem:-

(B). Lateral meristem:-

(C). Intercallary meristem:-

(A). Apical meristem:-

§  Position: present at apical parts of plant such as root tip and shoot tip

§  It helps in increase in height of plants.

§  Apical meristem has two distinct zone:

§  Promeristem zone: contains group of dividing cell (apical initials)

§  Meristematic zone: contains protoderms (epiderm), procambium (primary vascular tissue) and ground meristem (cortex and pith).

§  The cells of this meristem are responsible for linear growth of an organ.

§  E.g .Root apical meristem & shoot apical meristem.

(B). Lateral meristem:-

§  Position: present in intercalary position in the leaves and internode

§  It is a part of apical meristem

§  It also adds to height of plants

§  Commonly present in monocots, grass and pines

§  Lateral meristem consists of initials which devide mainly in one place and cause the organ to increase in girth.

§  The lateral merestem usually occurs beneath the bark of tree, in the form of cork cambium.

(C). Intercallary meristem:-

§  Position: present on lateral side of stem and root

§  It helps in increases the diameter or thickness of plants.

§  Example: vascular cambium (primary meristem) and cork cambium (secondary meristem)

§  Intercallary meristem is located in between the regions of permanent tissues.

§  The intercalary meristem are usually present on the base of node.

§  This tissue is responsible for growth in length of plant stem and also length of leaves and other organs etc.  

                               

 

(2). PERMANENT TISSUE:-Permanent tissue originates from meristematic tissue and become permanent tissue at fixed position in a plant body. The cells of this tissue possesses are mature, have definite shape , size and function and have intercellular spaces. They have lost their power of division. Permanent may be living or dead. Cells of this tissue are vacuolated. The permanent  tissue is classified into two main groups:

Types of permanent tissue

1.      Simple permanent tissue

2.      Complex permanent tissue

 (A).SIMPLE PERMANENT TISSUE:- These permanent tissues are called simple permanent tissue because they are composed of similar type of cells which have common origin and function. They are further classified into three types:-

(i).Parenchyma

(ii).Collenchyma

(iii).Sclerenchyma

(i). PARENCHYMA:-

Characteristics of parenchyma tissue

§  Living tissue

§  Shape: each cell is spherical, oval, rectangular, polygonal, elongated or irregular in shape

§  Cell wall: thin walled made up of cellulose, hemicellulose and pectin

§  Young Parenchymatous cells are loosely arranged

§  Intercellular space : present

§  Food storage: cell store reserve food material

§  Parenchyma is found in all parts of plant such as cortex, pith, palisade, mesophyll, flower, seed etc

§  It is also found in vascular tissues.

§  Each cell of this tissue has a prominent nucleus

SHAPE:- Parenchyma cells occur in many shapes like oval or rounded or polygonal.

DISTRIBUTION:-Parenchyma cells are found in softer parts of a plant like in the roots, stem, leaves, flowers and fruits. It is also found in xylem.

Function of parenchyma tissue:

§  Photosynthesis: chlorenchyma contains chloroplast which helps in photosynthesis

§  Storage: parenchyma cell stores food in the form of starch, proteins, oils and fats.

§  Buoyancy: helps in floating of aquatic plants due to presence of aerenchyma tissue

§  Secretion: Idioblastic cell secretes resins, latex, tannin, oils etc

§  Transport: parenchyma of xylem and phloem helps in transport of nutrition and water.

§  Mechanical support: Prosenchyma tissue provide mechanical support.

Types of parenchyma tissue

ii. Aerenchyma: it is a type of parenchyma cell having large intercellular air space. Eg present in cortex of hydrophytes

iii. Chlorenchyma: it is a parecnhyma cell containing chloroplasts. Eg present in palisade of leaves and helps in photosynthesis 

i. Prosenchyma: it is long and tapering parenchymatous cell present in some plants. Eg pericylce

 

 

(ii). COLLENCHYMA:-

Characteristics of collenchyma tissue:

§  Living tissue

§  Shape: each cell is somewhat elongated

§  Cell wall: thick walled due to deposition of hemicellulose and pectin in intercellular space

§  Intercellular space: present or absent

DISTRIBUTION:-These cells arte found in leaf stalks and forms hypodermis of a plant.

 

                                                                Functions of collenchyma tissue

§  Mechanical support: It is living mechanical tissue

§  Photosynthesis: It contain chloroplast and carry out photosynthesis.

Types of collenchyma tissue:

i. Angular collenchyma: thick cell wall at corner of cell; without intercellular space

ii. Lacunar collenchyma: thick wall at boarder of cell; large intercellular space

iii. Plate or lamellar collenchyma: thick wall at tangential wall; without intercellular space                                              

(iii). SCLERENCHYMA:-

§  Dead tissue

§  Shape: elongated and pointed at both end

§  Cell wall: thick and lignified

§  Cell lack protoplasm

§  It gives strength and rigidity to the plant body

                    

DISTRIBUTION:- Sclerenchyma cells mostly occur in hypodermis. They are found in clusters. They also occur in hard seed coats.

FUNCTION:-

1. Sclerenchyma produces mechanical strength to the plant.

2. Sclerenchyma protects the plant from environmental forces like winds.

Types of sclerenchyma tissue                                                                                                                     Fibres

                                                                                                                                                                    Sclereids (stone cell)

i. Fibres:

§  it is thick walled,long and pointed dead cell

§  Cell wall contains simple, oblique or bordered pits.

§  Present in xylem, covering of fruits

§  Gives mechanical supports

ii. Sclereids (stone cell):

§  extremely thick walled cell with spherical, oval or dumbbell shape.

§  Cell wall contains simple pits

§  Present in hard part of plants, pulp of fruits

§  Provide local mechanical supports

 

(B). COMPLEX PERMANENT TISSUE:- Complex permanent tissue may be defined as the group of more than one type of cells having a common origin  & common function.. And working together as a unit to perform a common function. It is also known as vascular tissue.

Types of complex tissue:

I. Xylem

II. Phloem

 I. Xylem

§  The function of xylem is to transport water and minerals from the root to the leaves of plants.

§  It also provides support to plants.

§  Xylem is also known as wood

§  Xylem is composed of four types of cells-Tracheids, Vessels, Xylem fibres and Xylem parenchyma.                                                                                                                                      

§  Trachieds:

§  Trachieds are elongated cell with tapering end

§  They are dead cells with lignified cell wall

§  Function: conduction of water and minerals from root to leaves and also provide mechanical support

§  Types: annular, spiral, reticular, sclariform and pitted                                                                   

§  Vessels/ Tracheae:

Vessels are long, cylindrical, tube like dead cells

§  Vessels are main element of xylem for conduction                                                                        

§  Xylem fibres:

§  They are sclerenchymatous cell

§  They are dead cells

§  They provide mechanical support                                                                                                            

§  Xylem Parenchyma:

§  They are parenchymatous cell

§  They are living cells

§  Function: storage of food in the form of starch or fat

 II. Pholem

§  Phloem is responsible for the conduction or transport of organic food synthesized by the s to different part of plant body.

§  Phloem is also known as bast.

§  Phloem is composed of four types of cells-Sieve tubes, Companion cells, Phloem parenchyma and Bast fibres                                                                                                                             

 

§   Sieve tubes

§  They are tube like structure composed of elongated cell arranged by end to end

§  Sieve element or cell lack nucleus

§  Function: transport of organic food from leaves to different parts                                                 

 

§  Companion cells:

§  They are thin walled, elongated living cells.

§  Each cell contains large nucleus

§  Companion cell are present only in angiosperm

§  Function: support sieve cell in conduction of food.

         Phloem parenchyma:

§  They are living parenchymatous cells

§  Function: storage of food in the form of starch or fat. It also store tannin and resins                     

§  Bast fibres/ Phloem fibres:

§  They are sclerenchymatous cell.

§  They are dead cells.

§  Function: mechanical supports

ANIMAL TISSUE:  The body of animals is also made up of different types of tissues, which perform specific function .e.g The contraction and relaxation of muscle cells result in the movement of body      parts. Blood carry substances from one part to another , this function is performed by another type of tissue.

          On the basis of functions they perform the animal tissue is of four types and are:-

(A) Epithelial tissue:-

(B) Muscular tissue:-

(C)  Connective tissue:-

(D)  Nervous tissue:-

(A) EPITHELIAL TISSUE:- Epithelial tissue shields the surface of all internal as well as external organs. All layers and organs in the body are lined by a group of tissues which are commonly referred to as epithelium. This animal tissue is highly permeable as it plays a significant role in the exchange of substances across the cells and helps in maintaining the osmoregulation.

Characteristics of epithelial tissue:-

1.The cells of epithelial tissue are closely packed.

2.Intercellular spaces are absent.

3.The surface of epithelial cells may be smooth or may have hair like projections called cilia.

Functions of epithelial tissue:-

·         They act as a protective barrier against injury and invasion of pathogens like viruses, bacteria,  etc

·         The main functions of epithelial tissue include protection, secretion, sensation, and absorption.. Some epithelial also secrete substances like digestive juices or absorb nutrients and prevents water loss from the body.

·         It also provides protection against drying up of inner tissue.

·         It also protects us from harmful chemical touch to inner tissue.

 

 

TYPES OF EPITHELIAL TISSUE:-

On the basis of the structure of the epithelial cells, the epithelial cells are classified as:-

(i).Squamous epithelial

(ii).Cuboidal epithelial

(iii).Columnar epithelial

(iv).Ciliated epithelial

(v).Glandular epithelial

(i).SQUAMOUS EPITHELIAL:-This epithelial consists of thin, flat, Irrigular shaped cells which fit together closely. This tissue lines  the blood vessels, Urinary tubules, alveoli of lungs, buccal cavity and food pipe. This tissue provides protection to the underlying parts.

                                                   

(ii).CUBOIDAL EPITHELIAL:-This tissue consists of cube like cells. The cuboidal epithelial lines the salivary ducts, pancreatic ducts, sweat glands and thyroid glands. It helps in protection, Secretion and Absorption.

                                             

(iii).COLUMNAR EPITHELIAL:- This tissue consists of tall and pillar like cells. The columnar epithelial lines the stomach, Intestines and Gall bladder. This tissue helps in protection, Secretion and Absorption.

                                                 

(iv).CILIATED EPITHELIAL:- This tissue consists of cube like cells which have cilia on cell surface. Ciliated epithelial lines some part of Urinary tubules, Nasal passage, Fallopian tubes and bronchioles. This epithelium generally helps in movement of substances.

                            

(v). GLANDULAR EPITHELIUM:- This tissue consists of columnar cells but are modified to secrete chemicals. This epithelium lines Glands such as gastric glands, Intestinal glands. Glandular epithelium generally secretes chemicals.

                                                                 

(B).MUSCULAR TISSUE:- It consists of long narrow muscle cells. These are also called as muscle fibres. Muscle fibre can contain one or more than one nuclei. Muscle cells cause movement of body parts. Movement of any organ Is done by contraction and relaxation of muscle cells.

There are three types of muscle cells and are:-

(i). Straited muscles

(ii). Unstraited muscles

(iii).Cardaic muscles

(i).STRAITED MUSCLES:- The striated muscles consists of long, narrow, cylindrical, unbranched fibre with blunt ends. These muscles are attached to the bone sby tendons. They are also called as skeletal muscles. Skeletal muscles are in our own control hence they are also called as voluntary muscles. The striated muscles are found in body wall and the limbs. They also occur in tongue. The striated muscles help in the movement of body parts.

(ii).UNSTRAITED MUSCLES:- Each unstraited muscle fibre is long, narrow, spindle shaped with pointed ends and has only one nucleus. The unstraited muscles occur with in the walls of tubular visceral organs except heart. Thus unstraited muscles occur in the walls of alimentary canal, ducts, blood vessels, urinary bladder etc.Unstraited muscles are also found in the iris of the eye. Unstraited muscles are involuntary ,that is they do not work according to our will. They also contracts and relaxes.

                                                 

(iii).CARDIAC MUSCLES:- The cardiac muscle consists of short cylindrical branched muscle fibres which are joined end to end to form a network. Each cardiac muscle fibre contains more than one nuclei. Intercellular spaces between cardiac muscle fibres are also present. They are also involuntary. Cardiac muscles are only found in heart. Cardiac muscles contract and relaxes rapidly but never gets fatigued.

                                            

                      

(C). CONNECTIVE TISSUE:- Connective tissue supports in connecting or separating other tissues or organs of the body as the name suggests. A fibrous connective tissue is strong and is found in areas like ligaments, which basically connects bones to one another. Connective tissues happen to be the most abundant tissues of complex animals as they include cartilage, bone, adipose, and blood. All connective tissues except blood tend to secrete structural proteins called collagen or elastin.. Connective tissue also carries material from one part to another in the body. The cells of connective tissue are living and remains separated from each other.

Functions of connective tissue:-

1. The main functions of connective tissue are binding, Supporting and packing.

2. Connective tissue also acts as phagocytes. That is they kill the pathogen which enters inside the body.

Types of connective tissue:-

(i).Areolar connective tissue:-

(ii).Dense regular connective tissue:-

(iii).Adipose tissue:-

(iv).Skeletal connective tissue:-

(v).Vacuolar connective tissue:-

(i).AREOLAR CONNECTIVE TISSUE:- It is widely distributed in the animal body. It consists of a sticky matrix containing fibres and cells. This tissue provides packing material in various organs. It also binds skin with the underlying tissue. It helps in the repair of body tissues during injury.

                                                               

(ii).DENSE REGULAR CONNECTIVE TISSUE:- This tissue consists of packed fibres and cells. This tissue is of two types:-

(a). Tendon                 (b). Ligament

(a). TENDON:- Tendon is the cord like structure, very tough and inelastic in nature. The tendons connect the muscles with bone.

(b).LIGAMENT:- Ligament is the cord like elastic in nature. The ligament connect bone with bone.

(iii).ADIPOSE CONNECTIVE TISSUE:- Adipose tissue is a fat storing tissue, in which large , spherical or fat cells are present. The adipose tissue is found beneath the skin, in the covering of heart, in yellow bone marrow and kidneys. Adipose tissue prevents the heat loss from the body. Adipose tissue helps in the storing of fats. It is also considered as shock absorber.

 

(iv).SKELETAL CONNECTIVE TISSUE:- This tissue forms the rigid skeleton which support the vertebrates. It helps in locomotion and provides protection to many vital organs. Skeletal tissue is of two types:-

(a).Cartilage               (b). Bone

(a).Cartilage:- This tissue is elastic and soft than bone. In humans the cartilage occurs at the ends of long bones, The pinna of ears, The end of nose and the walls of wind pipe. It provides flexibility.

(b).Bone:-It is hard, strong and non flexible skeletal tissue. Bones  form endoskeletal  of vertebrates. They also provides support for soft parts of the body.

(v).VACUOLAR CONNECTIVE TISSUE:- It is also known as fluid tissue and it consists of blood and lymph.

Blood:- It is the important connective tissue which consists of plasma and cells. Cells of blood include RBC, WBC and Platelet.

Functions of blood:-

1. Blood transports gases like oxygen and carbon di-oxide.

2. It maintains body temperature.

Lymph:- Lymph is a colourless  fluid present inside our body. it is transported through lymphatic vessels inside the body.

Functions of lymph:-

1.It transport fats.

2.It drains excess fluid from intercellular spaces back into the blood.

 

(D). NERVOUS TISSUE:- Nervous tissue is only present in brain, spinal cord and nerves. Nervous tissue is the term for groups of organized cells in the nervous system, which is the organ system that controls the body’s movements, sends and carries signals to and from the different parts of the body, and has a role in controlling bodily functions such as digestion. Nervous tissue is grouped into two main categories: neurons and neuroglia. Neurons, or nerves, transmit electrical impulses, while neuroglia do not; neuroglia have many other functions including supporting and protecting neurons.. Neuron is a star shaped cell with a long tail and consists of three parts.

(a). Cell body                  (b). Dendrites                     (c). Axon.

 

Functions of nervous tissue:-

1.      Nervous tissue is responsible for transmission of messages.

           

  

                                          TEXTUAL QUESTIONS

Q NO 1:- What is a Tissue?

ANS:- A group of cells similar in structure that work together & to perform  a particular function is called a tissue.

Q NO 2:- What is the utility of tissues in multicellular organisms?

ANS:- In multicellular organisms each specilised function is taken up by a different group of cells. These cells carry out only a particular function . so the multicellular organisms show division of labour.

Q NO 3:- Name types of simple tissues ?

ANS:- Parenchyma , Collenchyma , Sclerenchyma.

Q NO 4:-Where is apical meristem found ?

ANS:- Apical meristem is found at the growing tips of stem & roots.

Q NO 5:- Which tissues makes the husk of coconut?

ANS:- Sclerenchyma tissue makes the husk of the coconut.

Q NO 6:- What are the constituents of phloem?

ANS:- The main constituents of phloem are:

           (a)Sieve tube. (b) Companion cell. (c) Phloem parenchyma. (d) phloem fibres

Q NO 7:- Name the tissue responsible for movement in our body?

ANS:- Muscular tissue is the tissue responsible for movement in our body.

Q NO 8:- How does a neuron look like?

 ANS:- A neuron look like a star shaped cell with a tail.

Q NO 9:- Give three features of cardiac muscles?

ANS:- (1). Cardiac muscles have stripes or light and dark bands.

           (2). These muscle fibres are straited, cylindrical and branched in structure.

           (3). These are involuntary and fast and never gets fatigued.

Q NO 10:- What are the functions of Areolar tissue?

ANS:- (1). It helps in repair of tissues after  injury.

           (2). It fixes skin to underlying muscles.

           (3).It also helps in combating foreign  toxins.

Q NO 11:- Define the term tissue?

ANS:- ALREADY DONE:-

Q NO 12:-How many types of elements of elements together make up the xylem tissue? Name them?

ANS:- Xylem is composed of following elements.

        (a). Tracheids.   (b). Vessels.    (c).  Xylem parenchyma.   (d). Xylem fibres.

Q NO 13:- How are simple tissue different from complex tissues in plants?

ANS:-  

Simple tissues	Complex tissues.
1. These are made up of one type of cells. 2.The main function of these tissues are storage and mechanical support. These do not transport substance.   3. Example: parenchyma, collenchyma   sclerenchyma.	1.These are made up of more than one type of cells. 2. The main function of these tissues is conduction of water, minerals (xylem) and food prepared by leaves (phloem).They are therefore called as vascular tissues too. 3. Example: xylem, phloem.

Q NO 14:-Differentiate  between parenchyma , Collenchyma & Sclerenchyma on the basis of their cell wall?

ANS:-

PARENCHYMA	COLLENCHYMA	SCLERENCHYMA
1.Cells are thin walled and composed of cellulose, hemi cellulose or pectin.   2. These are loosely packed with intercellular spaces between them.	1. Cells are thin walled but thickened at angles due to deposition of cellulose or pectin at corners. 2. Inter cellular spaces are either very little or absent.	1. Cells are very thin walled due to the deposition of lignin. At some areas the walls are comparatively thin (pits). 2.Compactly packed So, intercellular spaces are absent.

Q NO 15:-What are the functions of the stomata?

ANS:- The function of stomata are:-

     (1). Exchange of gases like CO2 and O2 with the atmosphere.

     (2). The loss of excess water in the form of water vapors , which is known as  

            transpiration.

Q NO 16:- Diagrammatically show the difference between the three types of muscle tissue?

                           

Q NO 16:- What is the specific function of the cardiac muscles?  

ANS:- The specific function of cardiac muscle is to contract and relax rhythmically (heart beat) throughout the life without any fatigue.                                                                                 

   Q NO 17:- Differentiate between striated, unstriated and cardiac muscles on the basis of the structure and site/ location in the body.                                                       ANS:-

STRAITED MUSCLES	UNSTRAITED MUSCLES	CARDIAC MUSCLES
1. Long, cylindrical and un branched cells with blunt ends. 2. Multi nucleated cells. 3. The cells have alternate dark and light bands called striations. 4. Unbranched cells.	1. Long cells with pointed ends.   2. Uni -nucleated cells. 3. No striations or stripes are present. 4. Unbranched cells.	1. Long cells with blunt ends. 2. Cells have one or two nuclei  in the Centre. 3. Faintstriations are present. 4. Cells are branched.
These are found in the limbs and are mostly attached to bones.	These are found mostly in the walls of blood vessels, alimentary canal, ureters and Bronchi (lungs) etc.	These are found in the walls of heart exclusively.

Q NO 18:-Draw a labelled diagram of a neuron.

                                                                 

Q NO 16:- Name the following?                                                                                            (a) Tissue that forms the lining of our mouth.                                                                      ANS:- Epithelial tissue.

(b) Tissue that connects muscle to bone in humans.

ANS:- Tendon

(c) Tissue that transports food in plants.

ANS:- Phloem.

(d). Tissue that stores fat in our body.

ANS:- Adipose tissue.

(e). Connective tissue with a fluid matrix.

ANS:- Blood.

(f). Tissue present in brain.

ANS:- Nervous tissue.

Q NO 17:- Identify the type of tissue in the following: Skin, Bark of tree, Bone, Lining of kidney, Tubule, Vascular bundle.

ANS:- Skin:- Stratified squamous epithelial tissue

           Bark of tree:- Simple permanent tissue.

           Bone:- Connective tissue.

           Lining of kidney:- Cuboidal epithelial tissue.

           Vascular bundle:- Complex permanent tissue.

Q NO 18:- Name the regions in which parenchyma tissue is present?

ANS:- Leaves, fruits & the flowers are the regions where the parenchyma tissue is present.

Q NO 19:- What is the role of epidermis in plants?

ANS:- Epidermis in plants performs the following  functions:

        (1).It is a protective tissue of the plant body.

        (2).It protects the plant against mechanical injury.

        (3). It  allows exchange of gases through the stomata.

Q NO 20:- How does the cork act as a protective tissue?

ANS:- The outer protective layer or bark of a tree is known as the cork, it is made up of dead cells. Therefore it protects the plant against mechanical injury, high temperature etc. it also prevents the loss of water by evaporation.

 

 

 

 

 

 

                                                                    

TOPIC :-CELL         (BIOLOGY)

The word cell is derived from the Latin word “cellula” which means “a little room” 

·        It was the British botanist Robert Hook who, in 1664, while examining a slice of cork under a microscope, found its structure resembling the box-like living quarters of the monks in a monastery, and coined the word “cell                        

·        In the year 1838, Matthias Schleiden, a German botanist, first proposed the idea that all plants consist of cells                                                                                                             

·        The Dutch scientist A.V.Leeuwen-hook, in 1674, discovered the minute forms of life such as bacteria and single celled animals in a drop of water                                   

·        In 1831, Robert Brown discovered the nucleus in the cell                                                      

·        In 1932, two German Scientists, Ruska and Knoll, invented the electron microscope.

·        In 1839, Theodar Schwann, another German botanist, asserted that all plants and animals are made up of cells                                                                                              

·        in 1840  J.E.Purkinje  used the term protoplasm to describe the juicy, slimy   gelatinous contents of the cell                                                                                                                   

·       In 1885, Rudolf Virchow Proposed theory of cell lineage that means all cells arise from pre-existing cells.                        

CYTOLOGY:- The branch of Biology which deals with the study of cells.

 

TWO TYPES OF ORGANISMS:-

On the basis of number of cells, organisms are devided into two categories:-

·       Unicellular Organisms :- Unicellular organisms are known as singled-celled organisms. They are made up of a single cell. Organisms like the Amoeba, Paramecium are single-celled organisms. They are the oldest forms of life. They existed about 3.8 million years ago. Bacteria, protozoa, unicellular algae, and unicellular fungi are the main groups of unicellular organisms. The single cell regulates all the activity of the organism. Most of the Unicellular organisms are invisible to the naked eye.

·       Multicellular Organisms :-Organisms that consist of more than one cell are known as multicellular organisms. Multicellular organisms are made up of more than one cell. These cells identify and attach to each other to form a multicellular organism. Most of the multicellular are visible to naked eye. Organisms like plants, animals, and some algae arise from a single cell and they grow up into a multi-celled organism. 

                         

 

 

CELL & ITS DIVERSITY:-

Cell is the basic structural & functional unit of life. All the living organisms are made upof cells.Organisms made up of cells may be broadly classified into two kinds:

Unicellular  and  Multicellular  

               All living organisms, whether plants or animals, are made up of microscopic units called cells. The cell occupies the same central position in biology as the atom in the physical sciences.
               All living beings, plants and animals, start their life with a single cell. Some organisms exist as a single cell and carry out the various metabolic life processes such as assimilation, respiration, reproduction, excretion, etc., that are essential for their survival. These organisms are known as unicellular organisms. E.g: Amoeba & Paramecium.

Cells show great diversity in form and functions. Because of this, it was not easy to realize that all living organisms are made up of units sharing a common basic structure. Every unit is a cell. The other major issue for the discovering of the cell was the very small size they usually show.

1. Cell size:-

Cell size is measured in micrometers (µm). One micrometer, or micron, is one thousandth of a millimeter (10^-3 millimeters), and one millionth of a meter (10^-6 meters). A typical eukaryote cell is between 10 and 30 µm in size. This is true for the cells of a worm and for those of an elephant, but there are many more cells in the elephant. To be aware of how small the cells are, imagine a 1.70 meters tall person which is stretched to match the height of the Everest, which is about 8500 meters. The stretched giant cells of that person would measure only 1.3 centimeters, i.e., smaller than an euro cent coin (then, it would be a giant formed by a huge amount of euro cent coins).

However, there are eukaryote cells having uncommon dimensions. They can be very small, like sperm cells, whose head may be smaller than 4 µm in diameter, while others like the eggs of some birds and reptiles can be larger than 10 centimeters (thousands of microns) in their larger axis, but we should measure only the yolk, since the egg white is not part of the cell. An extreme example is the egg of ostriches. Some cells may have cytoplasmic extensions as large as several meters in length, such as the brain neurons of giraffes that innervate the more caudal part of the spinal cord. Smaller than eukaryote cells are prokaryote cells, which typically are around 1 to 2 µm in diameter, being Mycoplasma the smallest with 0.5 µm.

              

 

 

2. Number:-

Most living organisms are unicellular, i.e., a single cell. Prokaryotes (bacteria and archaea) are the most abundant unicellular organisms. Unicellular eukaryote species are abundant too. Organisms that can be observed without microscopes are mostly multicellular, i.e., they are made up of many cells. Multicellular organisms are animals, plants, fungi and some algae. In general, larger multicellular organisms contain higher number of cells since they have a similar average cell size. Estimates of the total number of cells of an organism with similar size to humans may range from 10¹³ (1 followed by 13 zeros) to 10¹⁴ (1 followed by 14 zeros). To be aware of these numbers, it is estimated that the total number of cells in the human brain is about 86x10⁹ neurons and of a mouse brain is about 15x10⁹. The most abundant cells of the human body are red blood cells and glial/neuron cells of the nervous system.

3. Morphology:-

Cell morphology is typically sketched as rounded, but this is probably the most uncommon shape (except for a few types of cells). Cell morphology in animal tissues is diverse, enormously diverse! It can range from rounded to star-like, from multi-lobed to filiform. Plant cells also show a wide diversity of forms, which is determined by the cell wall, being cuboidal and columnar shapes the most common shapes. 

4. Function:-

Every living organism needs to perform many functions to maintain its integrity, and to grow and proliferate, which are carried out by many cell types working coordinately. These functions are extremely complex and diverse, going from those related to food digestion, detoxification, movement, reproduction, support, defense against pathogens, to those related to thinking, emotions or consciousness. All these functions are carried out by specialized cells, such as those of the gastrointestinal epithelium, liver, muscle, germ cells, bone, lymphocytes and neurons, respectively. Cells need a particular molecular framework, mainly based on proteins, to carry out their functions. In an organism, some functions may be carried out by only one cell type, but the cooperation of several cell types acting in a coordinated way is commonly needed.

 

STRUCTURE OF A CELL:-

Cells vary in shape and size. They may be oval, spherical, rectangular, polygonal, spindle shaped, star shaped, rod-shaped or totally irregular like the nerve cell. The diversity in cells is in accordance with the role or function it has to perform as part of the tissue or organ system. In general, there is no typical shape for cells. Each Cell has three functional regions as mentioned below:

      (a)Plasma Membrane.

(b)Cytoplasm.

     (c)Nucleus.

      

CELL WALL:- Cell wall is present only in plant cells. A cell wall is an outer layer surrounding certain cells that is outside of the cell membrane. All cells have cell membranes, but generally only plants, fungi, algae, most bacteria, and archaea have cells with cell walls. The cell wall provides strength and structural support to the cell, and can control to some extent what types and concentrations of molecules enter and leave the cell. The materials that make up the cell wall differ depending on the type of organism. The cell wall has evolved many different times among different groups of organisms.

                   The main component of the plant cell wall is cellulose, a carbohydrate that forms long fibers and gives the cell wall its rigidity. Cellulose fibers group together to form bundles called microfibrils. Other important carbohydrates include hemicellulose, pectin, and liginin. These carbohydrates form a network along with structural proteins to form the cell wall. Plant cells that are in the process of growing have primary cell walls, which are thin. Once the cells are fully grown, they develop secondary cell walls. The secondary cell wall is a thick layer that is formed on the inside of the primary cell wall. This layer is what is usually meant when referring to a plant’s cell wall. There is also another layer in between plant cells called the middle lamella; it is pectin-rich and helps plant cells stick together. The cell walls of plant cells help them maintain turgor pressure, which is the pressure of the cell membrane pressing against the cell wall. Ideally, plants cells should have lots of water within them, leading to high turgidity. Whereas a cell without a cell wall, such as an animal cell, can swell and burst of too much water diffuses into it, plants need to be in hypotonic solutions (more water inside than outside, leading to lots of water entering the cell) to maintain turgor pressure and their structural shape. The cell wall efficiently holds water in so that the cell does not burst. When turgor pressure is lost, a plant will begin to wilt. Turgor pressure is what gives plant cells their characteristic square shape; the cells are full of water, so they fill up the space available and press against each other.

The cell wall has a few different functions. It is flexible, but provides strength to the cell, which helps protect the cell against physical damage. It also gives the cell its shape and allows the organism to maintain a certain shape overall. The cell wall can also provide protection from pathogens such as bacteria that are trying to invade the cell. The structure of the cell wall allows many small molecules to pass through it, but not larger molecules that could harm the cell.

                                                                      

 

PLASMA MEMBRANE/CELL MEMBRANE:- The cell membrane, also known as the plasma membrane, is a double layer of lipids and proteins that surrounds a cell and separates the cytoplasm (the contents of the cell) from its surrounding environment. Cell membrane is present in both plant and animal cells. It is selectively permeable, which means that it only lets certain molecules enter and exit. It can also control the amount of some substances that go into or out of the cell. All cells have a cell membrane.

          

Another way the cell membrane can bring molecules inside it is through endocytosis. This includes phagocytosis (“cell eating”) and pinocytosis (“cell drinking”). During these processes, the cell membrane forms a depression and surrounds the particle that it is engulfing. It then “pinches off” to form a small sphere of membrane called a vesicle that contains the molecule and transports it to wherever it will be used in the cell. Vesicles are also created from the cell membrane when endocytosis is not occurring, and are used to transport molecules to different areas within the cell. Cells can also get rid of molecules through exocytosis, which is the opposite of endocytosis. During exocytosis, vesicles come to the surface of the cell membrane, merge with it, and release their contents to the outside of the cell. Exocytosis removes the cell’s waste products– parts of molecules that are not used by the cell.                                                                                           The cell membrane also plays a role in cell signaling and communication. Receptor proteins on the cell membrane can bind to molecules of substances produced by other areas of the body, such as hormones. When a molecule binds to its target receptor on the membrane, it initiates asignal transduction pathway inside the cell that transmits the signal to the appropriate molecules. Then, the cell can perform the action specified by the signal molecule, such as making or stopping production of a certain protein. The cell membrane gives the cell its structure and regulates the materials that enter and leave the cell. Like a drawbridge intended to protect a castle and keep out enemies, the cell membrane only allows certain molecules to enter or exit. Oxygen, which cells need in order to carry out metabolic functions such as cellular respiration, and carbon dioxide, a byproduct of these functions, can easily enter and exit through the membrane. Water can also freely cross the membrane, although it does so at a slower rate. However, highly charged molecules, like ions, cannot directly pass through, nor can large macromolecules like carbohydrates or amino acids. Instead, these molecules must pass through proteins that are embedded in the membrane. In this way, the cell can control the rate of diffusion of these substances.

                                                                                                          

DIFFUSION:- The word diffusion derives from the Latin word, diffundere, which means "to spread way out". Diffusion is the net movement of molecules or atoms from a region of high concentration (or high chemical potential) to a region of low concentration (or low chemical potential) as a result of random motion of the molecules or atoms. Diffusion is driven by a gradient in chemical potential of the diffusing species.

A gradient is the change in the value of a quantity e.g. concentration, pressure, or temperature with the change in another variable, usually distance. A change in concentration over a distance is called a concentration gradient, a change in pressure over a distance is called a pressure gradient, and a change in temperature over a distance is called a temperature gradient.

                        

 

OSMOSIS:- If two solutions of different concentration are separated by a semi-permeable membrane which is permeable to the smaller solvent molecules but not to the larger solute molecules, then the solvent will tend to diffuse across the membrane from the less concentrated to the more concentrated solution. This process is called osmosis.                                                                    Osmosis is of great importance in biological processes where the solvent is water. The transport of water and other molecules across biological membranes is essential to many processes in living organisms. The energy which drives the process is usually discussed in terms of osmotic pressure. It is of two types                                                                                                                          

·        (1)Endosmosis:- Endosmosis is a type of osmosis. Endosmosis is the movement of a solvent (usually water) across a semi-permeable membrane from a outside a cell towards inside a cell where this is low solvent. This brings about swelling of the cell.

            Endosmosis increases the turgor pressure of a cell since the entering water causes the   

            cytoplasm to push against the cell membrane and cell wall (if a plant cell), causing the cell   

            to become turgid. Endosmosis can cause the cell to swell considerably as more and more

            water enters. If a cell is surrounded by pure water then too much water may enter to the

            point that the cell swells so much that it bursts, which occurs more often in animal cells

            than in plant cells since plant cells have a cell wall.

·       (2) Exosmosis:- Exosmosis is also a type of osmosis. Exosmosis is the movement of a solvent (usually water) across a semi-permeable membrane from inside a cell where there is high solvent, to outside a cell where this is low solvent. This brings about the shrinkage of the cell.                             

         When exosmosis occurs water moves out of the cell into the external environment. As this  

           happens the cytoplasm shrinks from water loss. If exosmosis occurs too rapidly and too

           much water is lost then the cytoplasm will shrink (plasmolysis). If the cytoplasm shrinks too  

           much it could cause the cell to shrink (more commonly occurs in animal cells than plant

           cells).

 

 

SIGNIFICANCE OF OSMOSIS:-

·        It helps in absorption of water from the soil by root hairs.

·        It helps in opening and closing of stomata on the leaves.

·        It includes the movement of leaflets of touch me not (Mimosa Pudica)

·        It also helps in growth of embryo during seed germination.

 

PROOFS OF OSMOSIS:-bb

                     SOLUTE:- A solute is defined as the substance that is dissolved in a solution. E.g:

                                      sugar, Salt. Etc.

         SOLVENT:- A liquid capable of dissolving another substance. E.g: Water, which can                

                           dissolve salt.

         SOLUTION:-A solution is a homogeneous type of mixture of two or more substances.

                            A solution has two parts: a solute and a solvent.

                                                  Solute  +  Solvent     Solution

 

Solutions are of three types based on the concentration of solute dissolved in a solution, and they are:

Hypotonic solution (Less Solute concentration)

Isotonic solution &

Hypertonic solution.(More solute concentration)

Hypotonic  solution:- It is that type of solution in which solute concentration is less than that of solvent. This solution enlarges a cell.

Isotonic  solution:- It is that type of solution in which solute concentration is same as that of remaining solution. This solution doesn’t effect and cell remains same sized.

Hypertonic  solution:- It is that type of solution in which solute concentration is more than that of remaining solution. This solution bursts a cell.

                 

Plasmolysis:- Plasmolysis is the process in which cells lose water in a hypertonic solution.

Deplasmolysis:- Deplasmolysis is the entrance of water into a plasmolysed plant cell, causing the cell membrane to return to the cell wall.                               

CYTOPLASM:- The term cytoplasm was given by Strausburger. The liquid part of the cell between the cell membrane and the nuclear membrane which includes the cytosol along with filaments, proteins, ions and macromolecular structures as well as the organelles suspended in the cytosol is called the cytoplasm. In eukaryotic cells, cytoplasm refers to the contents of the cell with the exception of the nucleus. Eukaryotes have elaborate mechanisms for maintaining a distinct nuclear compartment separate from the cytoplasm. Active transport is involved in the creation of these sub-cellular structures and for maintaining homeostasis with the cytoplasm. For prokaryotic cells, since they do not have a defined nuclear membrane, the cytoplasm also contains the cell’s primary genetic material. These cells are usually smaller in comparison to eukaryotes, and have a simpler internal organization of the cytoplasm.

Structure of Cytoplasm:-

The cytoplasm is unusual because it is unlike any other fluid found in the physical world. Liquids that are studied to understand diffusion usually contain a few solutes in an aqueous environment. However, the cytoplasm is a complex and crowded system containing a wide range of particles – from ions and small molecules, to proteins as well as giant multi protein complexes and organelles. These constituents are moved across the cell depending on the requirements of the cell along an elaborate cytoskeleton with the help of specialized motor proteins. The movement of such large particles also changes the physical properties of the cytosol.

The physical nature of the cytoplasm is variable. Sometimes, there is quick diffusion across the cell, making the cytoplasm resemble a colloidal solution. At other times, it appears to take on the properties of a gel-like or glass-like substance. It is said to have the properties of viscous as well as elastic materials – capable of deforming slowly under external force in addition to regaining its original shape with minimal loss of energy. Parts of the cytoplasm close to the plasma membrane are also ‘stiffer’ while the regions near the interior resemble free flowing liquids. These changes in the cytoplasm appear to be dependent on the metabolic processes within the cell and play an important role in carrying out specific functions and protecting the cell from stressors.

                        The cytoplasm consists of the matrix and the cell organelles. The matrix is a transparent semi fluid substance. When active, it is always in a state of movement. The organelles are found embedded in the cytoplasm. They have definite shape, structure and function. All the metabolic activities of the cell such as synthesis, secretion, digestion and energy generation, are performed by the different cell organelles. Cell organelles can be seen only with the help of an electron microscope.

CELL ORGANELLES:-

·        Endoplasmic Reticulum,

·        Golgi Apparatus,

·        Lysosome,

·        Vacuole,

·        Ribosome,

·        Centrosome,

·        Mitochondria,

·        Plastid. 

ENDOPLASMIC RETICULUM:-

This is a complex network of tubes called Cisternae, the lumen of these Cisternae is filled with fluid called endoplasmic matrix. Endoplasmic reticulum has three parts: Cisternae, Tubules & Vesicle. Cisternae are long interconnected , Flattened Sac like structures lying parallel to each other in the form of pile or stack. Inside these cisternae is a hollow space called Lumen in which is present a fluid called Endoplasmic matrix. Tubules are minute branched tube like structures attached to cisternae. Vesicles are bubble like structures produced at the ends of tubules and are finally pinched off to get attached with Golgi complex. Endoplasmic reticulum is devided into two types :

Smooth Endoplasmic Reticulum

Rough Endoplasmic Reticulum

·       Smooth Endoplasmic Reticulum:-  That endoplasmic reticulum which is without ribosomes attached to its cisternae. It is also known as agranulated endoplasmic reticulum. This endoplasmic reticulum is meant to synthesize Carbohydrates and Lipids.

·        Rough Endoplasmic Reticulum:- That endoplasmic reticulum which bears ribosomes to its surface. It is also known as granulated endoplasmic reticulum. This endoplasmic reticulum is meant to synthesize proteins.

                 The functions of the endoplasmic reticulum are to form the skeletal framework of the  

          cell, to provide a pathway for the distribution of nuclear material from one cell to the other  

          and to synthesize fats, steroids and cholesterol with the help of enzymes secreted by the

          cell.

                                                          

GOLGI APPARATUS:-  
 Discovered by Camelo Golgi in 1894 and are Also known as Golgi Complex or Golgi Bodies, or Lipochondria because they are rich in lipids. they consist of tiny, elongated, flattened sacs (cisternae), which are stacked parallel to one another along with some vacuoles and clusters of vesicles. However the plant cells contain many freely distributed subunits of Golgi apparatus, called Dictyosomes. Cisternae are formed at one end of the stack, called Cis face of Golgi apparatus. If the cisternae are budded off as vesicles at the other end of the stack, called Trans face of Golgi Apparatus. Golgi Apparatus is absent in Bacteria, Red blood cells of Mammals , Blue green Algae & Mature sperm cells.The function of the golgi body is to secrete certain hormones and enzymes. It also forms lysosomes and peroxisomes. The golgi body is usually found close to the nucleus.  

                                                                            

 LYSOSOMES:-
These are tiny, spherical, sac-like structures scattered all over the cytoplasm. Their main function is digestion. They contain powerful destructive enzymes capable of digesting all organic material, and hence called “digestive bags”.  Lysosomes are present in white blood cells are capable of digesting bacteria and viruses. During starvation, lysosomes digest proteins, fats and glycogen in the cytoplasm, and supply energy to the cell. They are also capable of digesting worn out cell organelles, or even digesting the entire damaged cell containing them. Hence, “suicide bag” is a sobriquet that is often used for Lysosomes.

                                   

VACUOLE:-                                                                                                           Discovered by Antonie-Van-Leewenhoek in 1676. Vacuole is a cell organell present only in plant cells. Vacuoles are generally absent in animal cells if present in animal cells are small in size and are temporary. Vacuole is membrane bound cell organell with single covering known as Tonoplast. Inside the vacuole is present a fluid called as Cell sap. Vacuole is meant for maintenance of water balance. Sometimes it is meant for ingestion of nutrient materials called as food vacuole.

                                     

RIBOSOME:- 
Discovered by George Emil Palade. Ribosomes are also called as Protein factory of the cell & Engine of the cell. These are spherical, granular particles which occur freely in the matrix of Mitochondria, attached to the rough endoplasmic reticulum. These are the smallest cell organelle and are always called as Ribonucleo proteins because they are made up of RNA (ribonucleic acid) and proteins, about 65% RNA & 35% proteins are present. This is the cell organelle present inside the other cell organelle and is called as the organelle with in the organelle (in mitochondria & in Plastid). They don’t have any membrane and are freely present in cytoplasm, sometimes attached with Endoplasmic reticulum and make their surface rough. Ribosomes are of Two types:

(a) 70 S

(b) 80 S

(a) 70 S:- These are present in the Prokaryotic cell. Tis 70 S ribosome is further divided into two sub-units: Large subunit and small sub-unit. Larger sub-unit is 50 S and smaller one is 30 S. (S stands for Swedberg or Sedimentation coefficient).

(b)80 S:- These are present in the Eukaryotic cell. This is also divided into two sub-units: Larger sub-unit and smaller sub-unit. Larger subunit is 60 S and smaller subunit is 40 S.

  When ribosomes are not synthesizing proteins at that stage ribosomal sub-units are detached from each other.When Mg²⁺ ion increases inside the cell,tgese ribosomal subunits are attached with each other and when Mg²⁺ ion decreases these subunits are detached from each other. Ribosomes are sometimes termed as Polysomes because during protein synthesis mRNA attaches with small sub-unit of ribosome and forms a chain of ribosomes, the larger sub-units form beats. This chain of ribosomes with mRNA known as polysome.

             Their function is to provide the surface for protein synthesis.  

                                               

 

 

CENTROSOME:-  
This is found in the cytoplasm near the outer surface of the nucleus and contains two cylinders called centrioles. Centrioles are surrounded with Amorphous Pericentriolar Material.The centrosome is found only in the animal cell. The centrosome and the centrioles play an important role by forming the poles of the spindle during cell division.  

                                   

MITOCHONDRIA:-
These may be cylindrical, rod-shaped or spherical and distributed in the cytoplasm. Each mitochondrion is bound by a double membrane. The inner membrane is folded into ridges called cristae, which increase the surface area of the membrane.
                 It is in the mitochondria that the sugar (food) is finally burnt during cellular respiration. The energy thus released from food is stored in the form of ATP (Adenosine tri-phosphate). Hence, mitochondria are termed as the “power house” or the “power plant” of the cell. The body cells use the energy stored in ATP for synthesis of new chemical compounds, the transport of these compounds and for mechanical work.

                                                

PLASTID:-                                                                                                                     

 

Plastid was discovered by Earnst Haeckel in 1866 term Plastid was coined by Earnst Haeckel also. Andreas Schimper gave the clear definition of Plastid. Plastid is a cell organelle found only in plant cells, Some protists like Euglena and are absent in animal cell. Like the mitochondria plastids also have their own DNA and ribosomes. Plastids are of two types on the basis of material inside them:-                                                                                                 

·       Chromoplasts                                                                                                   

·       Leucoplasts  

·       Chromoplast:-They are yellow , orange and red in colour, and they are found all those parts of plant which are exposed to sunlight like in flowers, leaf and fruits. Chromoplasts impart colour to flowers to attract insects for pollination and also perform photosynthesis. Chromoplast is divided into  three types on the basis of pigment they contain and are:-

Chloroplast

Pheoplast

Red Plast or Rhodoplast

(a)     Chloroplast:- These are the plastids which contain green color pigment called as chloroplyll.they are found in green leaves & green stems.

(b)          Pheoplast:- These are theplastid which contain Brown color pigment like Xanthjoplyll and Fucoxanthin. These are found in brown Algae.

(c)     Red Plast or Rhodoplast:- These are the plastids which contain red pigment like Phycoerythrin. These ra efound in red Algae

 

·       Leucoplasts:-They are colourless plastids with no Grana and they are found in the parts of a plant which are not exposed to sunlight like in roots, seeds and underground stem. These leucoplasts are associated with storage of food. Leucoplasts are of three types based upon the storage inside them and are:

Amyloplast

Proteinoplast or Aleuronplast

Elaioplast

(a)      Amyloplast:- These are the leucoplasts which store the carbohydrates.   These are found in Potato tuber, wheat and rice

(b)          Proteinoplast or Aleuronplast:- These are the leucoplasts which store proteins generally Aleuron protein. We can find them where protein is stored like in Pulses & Maize grain.

(c)     Elaioplast:- These are the leucoplasts which store fatsand are found in custard seeds, ground nut & sunflower.

·       The function of the chloroplast is to trap solar energy for photosynthesis. Leucoplasts store food in the form of carbohydrates, fats and proteins.

 

 

                                                       Chloroplasts:-

They are green colour plastids and are found in leaves of a plant. They are  involved in the process of photosynthesis. Each Choloroplast is bounded by two membranes like the mitochondria . Inside these two membranes is present a fluid called as Stroma. With in the stroma are stacks of membrane bounded , Flattened discoid sacs called as thylakoid. Pile of thylokoid is known as Granum.Each Granum is connected with next granum by a stalk like structure called as Lamella. Chloroplast is  also known as kitchen of the cell because they are involved in food making.

 

                             

NUCLEUS:-                                                                                                                                     This is a prominent, spherical or oval structure found at the centre of the cell. It is the controlling centre of all cell activities and has been described as the brain of the cell. It regulates all metabolic and hereditary activities of the cell.   
The nucleus is composed of the following structures:                                                                      

·       Nuclear Membrane   :                                                                                                                   

·       Nucleoplasm                                                                                                                                       

·       Nucleolus                                                                                                                                                

·       Chromatin Material.

Nuclear Membrane:-This is a double-layered membrane which separates the nucleoplasm from the cytoplasm. The nuclear membrane has minute pores which allow the selective transfer of material between the nucleoplasm and the cytoplasm.  

Nucleoplasm:- Within the nuclear membrane, completely filling up the space, is a clear, semi-solid, granular substance or matrix called the nucleoplasm. The nucleolus and the chromatin network lie suspended in the nucleoplasm.   

Nucleolus:-This dense, spherical granule found in the nucleus contains RNA (ribonucleic acid) which is responsible for protein synthesis in the cytoplasm.  

Chromatin Material:-These are very fine thread-like, coiled filaments uniformly distributed in the nucleoplasm. At the time of cell division, the chromatin becomes thick and ribbon like and are known as chromosomes. The chromosomes contain genes, which are composed of DNA (deoxy-ribonucleic acid). Genes are responsible for storing and transmitting hereditary characteristics from one generation to another. A gene is the functional unit of a chromosome. Genes are arranged in single linear order along the chromosome. One gene may be responsible for a single characteristic.

                                    

Prokaryotic and Eukaryotic Cells:-
The structure of the cell that we have studied so far is that of a eukaryotic cell.  The main difference between these two cell types is that prokaryotic cells do not have a nuclear membrane. The nuclear material consists of a single chromosome and lies in the cytoplasm. The nuclear region in the cytoplasm is called nucleoid. Membrane-bound organelles are absent. Prokaryotic cells are found in bacteria and cynobacteria (blue-green algai).

          Eukeryotic cells are complete. These cells contain membrane bound cell organells. The organisms which contain this type of cells are called Eukeryotes.

             

 

                   (Prokeryotic cell)                                                                                                  (Eukeryotic cell)          

               TEXTUAL QUESTIONS

Q 1:-What would happen if the plasma membrane ruptures or breaks down ?                                        ANS:-Plasma membrane is a selectively permeable membrane of the cell that maintains its constant internal chemical composition of the cell. If it ruptures or breakes down, the constant internal chemical composition of the cell will be lost and it will not be able to perform basic functions like respiration, nutrition, excretion, regeneration etc.                                                             

 

Q 2:-What would happen to the life of the cell if there was no Golgi Apparatus ?

ANS:-Golgi Apparatus is involved in the storage ,modification and packaging of the materials in vesicles. It is also involved in the formation of Lysosomes. The basic metabolic functions of the cells are not possible if Golgi Apparatus is not there.

 

Q 3:-Which Organelle is known as the Power house of the Cell?Why?

ANS:-Mitochondria are known as the power houses of the cell because they contain enzymes that are needed for oxidation of food materials(carbohydrates,fats,vitamins) present in the cells to Carbondioxide and water.Oxidation of food releases energy, which is used to form high energy ATP molecules. ATP is used to bring about energy requiring activities of the cell.

Q 4:-Where do the lipids and proteins constituting the cell membrane get synthesized?

ANS:-Smooth endoplasmic reticulum (SER) helps in the manufacture of lipids which are important for cell function. Ribosomes are the sites of Protein synthesis. The manufactured proteins  are  later sent to different places in the cell depending upon the need.

 Q 5:-How does an Amoeba obtain its food?

ANS:-Amoeba obtains its food through Endocytosis. Endocytosis refers to invgination of a small region of the plasma membrane, and ultimately forming an intra-cellular,  membrane –bound vesicle. This process is generally involved for the ingestion of food material. Intake of liquid food using endocytosis is called Pinocytosis or Cell drinking. Similarly, intake of solid particles by a cell through its cell membrane is called Phagocytosis or cell eating.

 

Q 6:-What is Osmosis? What are its types?

ANS:-The diffusion of water or solvent through a semipermeable membrane from a solution of higher concentration of water  to a solution of its lower concentration of water, is called osmosis. There are two types of Osmosis and they are

(1)Endosmosis:- Endosmosis is inward diffusion of water when the surrounding solution is less concentrated. This brings about swelling of the cell.

(2)Exosmosis:-Exosmosis is outward diffusion of water when the surrounding solution is more concentrated. This brings about the shrinkage of the cell.

 

Q 7:-Why are Lysosomes also called as suicidal bags?

ANS:-Lysosomes are small unit membrane bound sacs that store acid (Hydrolases). They digest food, foreign bodies and recycle cell components. Lysosomes are also known as Suicidal bags in view of their autolytic role in which a cell may digest its own cell organells like Mitochondria and E.R. In injured and dead cells, the lysosome membrane ruptures spontaneously releasing the enzymes that dissolves the weakened  cells.

 

Q 8:-Who discovered Cell and how ?                                                                                        ANS:- Cell was discovered by Robert Hook  in 1665.While he was examining a slice of Cork , under self designed microscope and on seeing under microscope he saw many little compartments . He called these compartments as Cells.

 

Q 9:-Why is the cell called as the structural and the basic unit of life ?

ANS:-All the organisms are made up of cells. All the life functions of an organism taking place inside the cell. Cells contain hereditary information necessary for regulating cell functions and for transmitting information to the next generation of the cell. Thus, cell is called the structural and functional unit of life

 

 

Q 10:-How do substances like CO2 and water move in and out of the cell? Discuss?

ANS:-CO2 moves in and out of the cell by diffusion while water does it by osmosis. When CO2 accumulates in high concentration inside the cell, at that time, the external environment of cell possesses low concentration of CO2 . In such condition, CO2 moves out of the cell from a region of its higher concentration to a region of its lower concentration by the process of diffusion. Similarly, water moves in and out through selectively permeable membrane. The  movement of water through a selectively permeable membrane is called Osmosis, where the passage of water is from a region of higher water concentration to a region of lower water concentration.

Q 11:-Why is plasma membrane called as the selectively permeable membrane?

ANS:-The plasma membrane allows the entry and exit of some selective materials in and out of the cell. Therefore, plasma membrane is called as selectively permeable membrane.

 

Q 12:-Can you name the two cell organells that contain their own genetic material?

ANS:-Mitochondria and plastids are the two cell organells, which have their own genetic material in them.

Q 13:-Where are the proteins synthesized inside the cell?

ANS:-Ribosomes are the sites where proteins are synthesized inside the cell.

Q 14:-Write differences between Prokaryotic and eukaryotic cell?

Prokaryotic  cell		Eukaryotic  cell
	1. True nucleus is not present. No nuclear      membrane is present. 2. A prokaryotic cell is a single membrane cell. 3. A prokaryotic cell lacks membrane bound cell organells. 4. Nucleolus is also absent. 5. Prokaryotic cells are present in Bacteria, Mycoplasma and Cynobacteria		1.  True nucleus is present. Nuclear membrane is present. 2. An Eukaryotic cell is a double membered cell. 3. An eukaryotic cell contains  cell organells.   4. Nucleolus is present. 5. Eukaryotic cells are present in Algae, Fungi,Plants and Animals

Q 16:-Write difference between Plant cell and Animal cell?

Plant cell	Animal cell
1. Cell wall is present. 2. Choloroplasts are present. 3. Big  vacuole is present .   4. Nucleus is pushed near the cell       membrane by the central Vacuole. 5. Plant cells are larger than Animal cells.	1. Cell wall is absent. 2. Choloroplasts are absent. 3. Vacuoles are generally absent, if present         are small in size.           4. Nucleus is generally near at the centre  of the cell. 5.Animal cells are generally small in size.

 

DIVERSITY IN LIVING ORGANISMS

WHY DO WE FALL ILL

                                                                                                                       

Health: Health is defined as a state of complete physical, mental and social well being and not merely freedom from diseases. In other words health means a state of body when it is free from disease, all organs and systems functioning properly with a perfect balance between the environment and the body. Therefore good health is having three dimensions. i.e. physical, mental and social health. Good health is an essential condition for purposeful existence. The important characteristics of a healthy individual are.

i.          Freedom from sickness and diseases.   

ii.       Freedom from unnecessary anxiety.

iii.     Freedom from social and physical tensions.

iv.     Cheerfulness and happy environment.

v.       Self confidence and sense of well being.

vi.     Ability to work efficiently and with enthusiasm.                                                                                                                              

 

Factors affecting the health: The various factors that affect the health of an individual are.

i.          Physical environmental factors like light, temperature, natural calamities etc. affect the health.

ii.       Social conditions like profession, housing, family atmosphere and economic conditions, neighbourhood, friendship etc.

iii.     Personal and community cleanliness conditions and health awareness education.

iv.     Supply of balanced diet for normal functioning of body.

v.       Sufficient economic condition in order to make strong and needed purchasing power for good health.

vi.     Regular and proper exercise and avoiding of certain hazardous substances like tobacco, alcohol and narcotic drugs.

 

Diseases: Any undesired condition which interferes with the normal functioning of the body and impairs the health of an individual is known as disease. It involves morphological (structural), physiological (functional) or psychological disturbances in some body parts. Disease may arise due to environmental pathogenic or genetic factors etc.

 

 

Types of disease: The human diseases are broadly grouped into four main categories.

i.          Acute diseases: Diseases which occur very rapidly but occur for a short period of time are known as acute diseases. Diseases like influenza are described as acute because their effects are sudden and quick but for shorter periods. e.g. common cold, fever, Cough etc.

ii.       Chronic diseases: The diseases which last for long time and cause prolonged poor health are known as chronic diseases. e.g. Elephantiasis, Asthma, tuberculosis etc.

iii.     Congenital diseases: Those diseases which are present in human beings since their birth are known as congenital diseases. These diseases are caused due to genetic abnormality or due to metabolic disorders or malfunctioning of any organ. These diseases can be inherited from parents to their children.

iv.     Acquired diseases: The diseases which occur in an individual only after their birth and are non-inheritable. On the basis of their communication, acquired diseases are of two types.  i.e. Communicable diseases and non-communicable diseases.

 

Infectious diseases: those diseases which are caused due to successful entry and multiplication of certain micro-organisms like bacteria, viruses etc. These diseases are always communicable and hence spread in the community regularly by various means like physical contact, water, air, food and insects. e.g. Cholera, T.B, Tetanus, Polio, Aids, Measles, Malaria amoebiasis etc.

 

Non-infectious diseases: The diseases which are not caused by the microbes but may caused by internal causes like genetic abnormalities or diet deficiency or hormone deficiency etc. These are non-communicable and cannot spread in community from person to person.e.g. Cancer, Diabetes, Dwarfism, Kwashiorkor, marasmus etc.

 

Causes of diseases (disease agents): Any substance which causes a disease by its excess or deficiency or absence is called a disease agent. The disease agents are of five types.

1.    Biological agents: The micro organisms which when successfully infect the human body, multiply and produce toxins which reduces the normal functioning of the body and cause disease are called as biological agents. They are also known as pathogens.                                       e.g. Bacteria, Viruses, Rickets, fungi, protozoan etc.

2.    Chemical agents: The endogenous chemicals like uric acid hormones, enzymes etc. and exogenous chemical (pollutants) like gases, dust, metals, fumes and allergies etc. are known as chemical agents.

3.    Nutritive agents: Minerals, carbohydrates, proteins, fats, vitamins and water are called nutritive agents and these lacks in food lead to many diseases.

4.    Physical agents: Heat, cold, radiations, sound etc. are known as physical agents and can cause many diseases like sunstroke, frost bite, impaired hearing and some other body disorders.

5.    Mechanical agents: The mechanical agents of disease include injuries, fractures, sprains, dislocations of bones etc. through accidents are known as mechanical agents.

 

Means of spread infectious diseases: Since most of the infectious diseases are communicable and spread from one person to other by the following means.

i.       Air borne diseases: some of the diseases like common cold sough, pneumonia and tuberculosis spread through air when an infected person sneezes or coughs and releases the infection in the air.

ii.    Water borne diseases: Some diseases like cholera and many other diseases which spread through water due to addition of some unwanted toxic substances like stools, faeces, other rubbish and hence spread through water.

iii.  Sexually transmitted diseases: Diseases like gonorrhoea, syphilis and AIDS are the disease which spread through sexual contacts from one person to another.

iv.  Vector borne diseases: Many animals which live with human beings may carry diseases and carry the infecting agents from a sick person to another potential host. Thus these animals act as intermediaries or vectors. Vectors are carrier of a disease of infection. Mosquitoes are vector of spread of malaria. In many species of mosquitoes, the females need highly nutritious food in the form of blood in order to be able to lay mature eggs. Hence, they feed on many warm blooded animals including human beings.

 

Manifestations of diseases: Diseases are characterised by malfunctioning of body and impairment of health. Diseases show many symptoms like headache, coughing, loose motions, wound with pus etc. but it is not always necessary that the diseases may show exact symptoms; sometimes many diseases show irrelevant symptoms. So there is need of laboratory testing of blood or urine or stool in order to study the disease properly.         

          The disease symptoms are divided into two categories. i.e. organ specific and tissue specific manifestations, and common manifestations.

 

Organ specific and tissue specific manifestations: These manifestations depend on the target organ which is the target of microbes after their entry. For example

i.             Lungs: The specific manifestations of lung diseases are cough breathlessness, chest pain and may be bloody sputum as in case of Tuberculosis and lung cancer.

ii.          Liver: Liver has the following manifestations. Inflammation of liver cells leading to jaundice characterised by yellowness of skin and eyes as in Hepatitis.

iii.        Intestines: Inflammation of intestinal mucosa leading to acute diarrhoea and dehydration as in cholera.

iv.        Nasal chambers: Inflammation of nasal mucosa leading to sneezing, bronchitis, coughing, fever, etc. as in influenza.

v.          Brain: Headaches, vomiting, fits or unconsciousness.

 

There are certain diseases in tissues specificity of the infection leads to very general seeming effects. e.g. In AIDS, the HIV virus attacks and kills the helper T-cells of cell mediated immune system so causes acquired immune deficiency in which number of T-cells drops even below 200 in comparison to 500-1500 in a normal person.   

The security of disease manifestations depends upon the number of microbes inside the body, or tissues or organ which the microbe targets.

 

Prevention of diseases: At present most of the diseases are curable but still there are certain disorders which are still incurable. Even there are three limitations of treatment approach o infectious diseases.

i.             Body functioning may never recover completely after disease.

ii.          Patient is bedridden for some time depending to severity of the disease.

iii.        Infected person acts as the source of spread of the disease to even healthy persons.

 

 

Keeping in view the above limitations, there are two ways of prevention measures to be taken.

1.    General ways of prevention of infectious diseases:

i.             For air borne diseases, we can prevent exposure by providing living conditions that are not overcrowded.

ii.          For water borne microbes, we can prevent exposure by providing safe drinking water.

iii.        For vector borne microbes or infections, we can provide clean environment. Such an environment which does not allow mosquito breeding or breeding of any other microbes.

2.    Specific ways of prevention of infectious diseases:

i.             Immunisation: A process by which a small amount of vaccine of a particular disease is introduced in the body of a healthy person. The vaccine after entering the body makes the body immune against a particular disease. Immunity is the ability of an organism to resist the development of a disease while the infected person with no disease is called immune. Immunity is provided by immune system which forms specific defence mechanism of an organism.

ii.          Vaccination: Vaccination is the most important method of preventing infection of organism, especially of bacteria and viruses. In this method, a vaccine (acts as an antigen) is inoculated inside the body, before the occurrence of disease, to stimulate the immune cells to produce antibodies. So a vaccine has antibody generating agents.

 

Principles of treatment: There are two ways of treatment of infectious diseases. i.e. symptom directed treatment and pathogen directed treatment.

1.    Symptom directed treatment: This treatment is directed to reduce the effect of the diseases which are generally due to inflammation of certain body tissues characterised by fever, pain, sneezing, vomiting, loose motions, redness of skin etc. It involves taking of medicines like antihistamine, anti pyretics like aspirin, crocin, analgesic etc.

2.    Pathogen directed diseases: This treatment is directed to kill the microbes with the help of certain chemicals. Different types of microbes have different and specific biochemical metabolic pathways. e.g. metabolic pathways of bacteria may be different from those of higher organisms. The medicinal chemicals are aimed to block these pathways so as to inhibit the synthesis of toxic products or respiration so as to lower the energy production. Most important therapeutic chemicals are antibiotics.

Antibiotics: Antibiotics are the substances, primarily produced by certain useful micro organisms which in low concentrations are antagonistic to the growth of harmful micro organism such as pathogenic bacteria. This property of antibiotics to kill the pathogenic microorganism is called as antibiosis. Some medicinally important antibiotics are pencillin, aureomycin, erythromycin, neomycin, streptomycin, terramycin, chloromycetin etc.

 

Q NO 1:- State any two conditions essential for good health?

ANS:- Two essential conditions  are :

(a). Being disease free.

(b). Having a clean, equal and harmonious environment necessary for good social and mental health.

 

Q NO 2:- State any two conditions essential for being free of disease.

ANS:- The two conditions essential for being free of disease are:

(a). Eating Balanced diet. As balanced diet helps in maintaining immune system.

(b). Maintaining personal, domestic and public hygiene as it helps keeping away from disease causing microbes.

 

Q NO 3:- Are the answers to the above questions necessarily the same or different? Why?

 

ANS:- The answers to above questions are not necessarily same because when we talk about disease we consider an individual but when we talk about "good health”, then we think about societies and communities. It is possible to be in poor health without actually suffering from a particular disease. Good health may mean different to different people like musician, dancer etc .But the similarities lie in the factors responsible to maintain good health as these help reducing the chances of catching diseases.

 

Q NO 4:- List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Why or why not?

 

ANS:- When there is a disease, one or more organs or tissues show changes which cause discomfort. These changes give rise to symptoms and signs of diseases. These symptoms may be headache, stomachache, vomiting, loose motions, cough etc. These symptoms indicate the presence of a disease but do not specify it.A single symptoms may indicate number of diseases. so, I would go to a doctor if only one symptom is present because he will diagnose the problem through definite indication of signs and can get laboratory tests done to find out the exact disease.

 

Q NO 5:- In which of the following case do you think the long term effects on your health are likely to be most unpleasant?

a. If you get jaundice,

b. If you get lice,

c. If you get acne. Why?

 

ANS:- If we get jaundice, then we would get long term effects on the health as it takes time to be cured and affects the general health poorly. One loses weight and needs complete rest along with medication. It is a chronic disease which has long term effects on one's health. But in case of lice or acne, the problem takes comparative very less time to be controlled and causes no major effect on general health.

 

Q NO 6:-Why are we normally advised to take bland and nourishing food when we are sick?

 

ANS:- During sickness, not only the immune system but the other system in our body also do not function well. In the case when body functions are not normal, we require the food which may provide adequate nutrients and can be digested easily. Therefore when we are sick, then bland and nourishing food is advised.

 

Q NO 7:- What are the different means by which infectious diseases are spread?

 

ANS:- Infectious diseases are generally caused by Pathogens. Infectious diseases can be spread through Air, through water, through sexual contact and also through vectors etc.

 

Q NO 8:- What precautions can you take in your school to reduce the incidence of infectious diseases?

 

ANS:- We can take following precautions in our school to reduce the incidence of infectious diseases.

(A).We must keep the surroundings clean.

(B).We must take care that the drinking water in the school must be clean.

(C).Closed dustbin should be kept.

(D).To get vaccinated in various vaccination programmes.

 

Q NO 9:- What is Immunization?

 

ANS:- Immunization is a process of injecting a vaccine into a healthy person to develop immunity against a particular disease.

 

Q NO 10:- Where are the immunization programmes available at the nearest health Centre in your locality? Which of these diseases are the major health problems in your area?

 

ANS:- At the health centre near our locality following immunization programmes are available.

           The major health problems in our locality are typhoid, tuberculosis, chicken- pox and measles.

 

Q NO 11:- How many times did you fall ill in the last one year? What were the illnesses?

a.    Think of one change you could make in your habits in order to avoid any of /most of the above illnesses.

b.    Think of one change you would wish for in your surroundings in order to avoid any of / most of the above illnesses.

 

ANS:- I was ill two times in the last year. I suffered with common cold that lasted for very short period of time and fever for some days only.

(a).Take proper care of your skin, hairs and nails as well as eye, ear, nose etc. balanced diet is essential to maintain good health .over- eating must be avoided.

(b).Maintain clean water supply. Unwanted solid refuse can be disposed on land by land fill or incineration.

 

Q NO 12:- A doctor/ nurse/health- worker is exposed to more sick people than others in the community. Find out how she / he avoids getting sick herself/ himself.

ANS:- A doctor / nurse /health – workers avoids getting sick herself by infections by preventing exposure to it. He/ she prevents by drinking safe and clean drinking water. The surroundings of a doctor or   nurse are always clean. More ever they know the causes, means of spread and signs of diseases and prevention as well as treatment e.g. use of gloves, different dresses etc.

 

Q NO 13:- Conduct a survey in your neighbourhood to find out what the three most common diseases are .suggest three steps that could be taken by your local authorities to bring down the incidence of these diseases.

 

ANS:- Common cold, influenza and typhoid fever are the three most common diseases in our neighbourhood.The public health programmes of childhood immunization good sanitation and disposal of faecal matter are necessary.

 

Q NO 14:- A baby is not able to tell her / his care takers that she / he is sick .What would help us to find out.

(a).That the baby is sick.

 

ANS:- Some symptoms and signs will tell that the baby is sick. These symptoms may be – cough, loose motion, high body temperature .vomiting etc. The baby will be irritable and may cry repeatedly.

 

(b).What is the sickness?

 

ANS:- Kind of sickness can be known by certain organ -specific and tissue -specific symptoms e.g. yellowness of skin and eyes indicate the jaundice and hepatitis.

 

Q NO 15:- Under which of the following condition is a person most likely to fall sick?

(a). When she is recovering from malaria.

(b). When she has recovered from malaria and is taking care of someone suffering from chicken pox.

(c). When she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken-pox. Why?

 

ANS:- When she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken- pox. Since when she was suffering from malaria, she had high fever and she may have lost her appetite due to nausea. In that situation the immune system fighting against disease becomes weak. After that she had a four- day fast too. That will weaken the immune system even more. With the state of health if she takes care of someone suffering from chicken – pox which is quite a contageous disease. She has definitely all the chances to fall sick.

 

Q NO 16:- Under which of the following conditions are you most like to fall sick?

a.    When you are taking examinations.

b.    When you have travelled by bus and train for two days.

c.     When your friend is suffering from measles. Why?

 

ANS:- I am most likely to fall sick when my friend is suffering from measles .since measles is an infectious disease which spreads through air. Being a friend if I sit by him or play or even go to visit him, I can catch the viral infection quite easily. The microbes get transmitted when the sick person coughs or sneezes through the droplets thrown in air. Therefore it is important to stay away.

 

NATURAL RESOURCES

Resources: A resource is any means of supplying a material held in reserve which can be transformed into more valuable and useful item. Natural resources are those living or non living substances available in the normal environment which are being exploited for supporting life and meeting human requirements. Resources are of two types; Natural and manmade resources. Natural resources are directly obtained from the nature i.e. forest, wildlife, minerals, air, water, solar energy, etc. Manmade resources are manufactured or synthesized by man, i.e. plastic, fertilizers, pesticides etc. 

 

Types of natural resources: The important types of natural resources are

i.       Inexhaustible Natural Resources: Resources that are unlimited in nature and are not likely to be exhausted by human activities fall under this category. Solar radiation, air, water, precipitation (rainfall, snow fall, etc.,) and atomic power are some instances of such resources. Some of them may undergo temporary imbalances due to human activity e.g. the quality of atmosphere due to air pollution.

ii.    Exhaustible natural resources: Natural resources that are limited in nature and are liable to be degraded in quantity and quality by human activities are exhaustible natural resources. Examples are forests, soil, wild animals, minerals, fossil fuels etc.

iii.  Renewable natural resources: The resources which can maintain themselves by natural recycling and reproduction or can be replenished if managed wisely. They include forests, crops, domestic animals, wildlife, ground water etc. they can last indefinitely and are not likely to be exhausted if a judicious balance is maintained between exploitation and replenishment.

iv.  Non-renewable resources: those resources which get exhausted with use because they cannot be recycled or replenished. They include metallic minerals and fossil fuels (coal, natural gas and minerals). In nature, these resources take several thousand years for their formation but the consumption of these resources by man is very fast.

 

Air: Air is an inexhaustible natural resource, essential for the survival of all the living organisms on earth. Air is a mixture of different gases; nitrogen and oxygen are the major components. Air present in atmosphere consists of 78% nitrogen 21% oxygen and remaining 1% is made up of other gases such as argon, neon, helium, krypton, xenon and radon.

Scientific studies have indicated that a normal human being requires about 250-265 kg air/day. Air is also necessary to grow crops, support animal life and is a medium for the sound waves to travel. About 95% of the total air in the atmosphere is present up to a height of 20 km above the earth’s surface. The remaining 5% of air is present up to a height of about 280 km.

 

Atmosphere: A thick gaseous envelope surrounding the earth is called atmosphere. The density of air in the atmosphere varies with altitude. It filters sunlight reaching the earth, affects climate and serves as a reservoir of elements essential for life (e.g. oxygen, nitrogen, CO₂ etc.). Atmosphere is divided into five different layers or zones: Troposphere, Stratosphere, Mesosphere, Ionosphere, and Exosphere.

          The percentage composition of atmospheric air is

                             

 

Air pollution: An undesirable change in the physical, chemical or biological characteristics of the air making it harmful for the living organisms including human beings is known as air pollution. In other words the addition of unwanted and harmful substances in the air or increase in the quantities of constituents of air beyond the normal level that affects the living organisms is called as air pollution.  The agents or the substances which pollute the air are called as air pollutants.

          The common air pollutants are dust, soot (carbon particles), ash, gases (carbon monoxide, excess of carbon dioxide, sulphur dioxide, oxides of nitrogen, hydrocarbons), chlorofluorocarbons (CFCs), asbestos dust, stone dust, cement dust, pollen grains of plants, radioactive rays etc.  The various harmful effects of the air pollution are

i.                   It can cause certain respiratory problems like allergy, bronchitis, asthma, and tuberculosis and lung cancer.

ii.                It can cause carbon monoxide poisoning and may lead to the availability of oxygen to the body tissues and can cause suffocation and even death.

iii.              Air pollution can lead to the formation of acid rain.

iv.              It may lead to the depletion of ozone layer of the atmosphere.

v.                Air pollution can lead to the global warming (increase in green house effect).

vi.              It may lead to many serious ailments like anemia, brain damage, convulsions and even death.

 

Ozone layer: Ozone is formed in the atmosphere when ultraviolet radiation from the Sun splits one oxygen molecule into two oxygen atoms (O₂). The atomic oxygen then combines with another oxygen molecule to form ozone (O₃). Most ozone found in the Earth’s atmosphere occurs in one layer in the stratosphere, between altitudes of around 20 to 50 km (12 to 30 miles). The ozone layer helps to produce the observed vertical structure of the atmosphere, and absorbs harmful ultraviolet radiation that would otherwise damage plant and animal life (also causing skin cancer) on the Earth’s surface. In contrast, ozone close to the Earth’s surface is a health hazard, as it is one of the major constituents of photochemical smog.

          The effects of ultraviolet radiations are: Cataract - eye lens becomes opaque causing blindness, inflammatory diseases, Skin cancer.

 

Depletion of ozone layer: Ozone layer or Ozonosphere lies about 18 – 50 km above the atmosphere. It has high concentration of ozone and is commonly called as ozone shield. This layer absorbs UV radiations and hence protects the life on the earth from harmful effects of UV radiations. Ozone layer is being depleted by the air pollutants. Chlorofluorocarbons are the air pollutants and are mainly responsible for the depletion of ozone layer in the atmosphere. Other ozone depleting substances are nitrogen oxides and hydrocarbons. Increasing human activities have resulted in production or release of high levels of various ozone depleting substances particularly chlorofluorocarbons. Due to the release of these substances in the atmosphere, these substances reach to the stratosphere and starts reacting with ozone layer and causes thinning of ozone layer over a particular area known as ozone hole. The depletion of ozone allows more UV radiations to pass through it and on striking with the earth produces the following harmful effects

i.       It can cause skin cancer.

ii.    It can cause damage to eyes, also increases the incidence of cataract in eyes.

iii.  It can cause damage to the immune system.

iv.  It can increase the incidence of harmful mutations and reduce in yields of plants.

 

Water: About 70-73% of earth is covered by water. Water is available in the form of oceans, seas, rivers, lakes, ponds, pools, polar ice caps and water vapour. The main component of hydrosphere is water. Water exists in all the three forms i.e., solid (snow), liquid (water) and gas (water vapour). Water is absolutely essential for the maintenance of life. The most important character of water is that its density is similar to that of protoplasm. Water consists of two atoms of hydrogen and one atom of oxygen. It is a universal solvent since it dissolves most of the compounds. Water is the fundamental natural resource. Human beings depend on water for drinking, cooking, agriculture, transportation, hydropower etc.

Water available in nature is of two types. i.e. Salt Water: It constitutes the oceans and the seas. Nature has comparatively more salt water than fresh water. Fresh Water: Fresh water is an unlimited natural resource. Its quality is often degraded but there is no reduction in quantity. There are three main sources of fresh water. i.e. Rainwater , Surface water (surface flow), Ground water.

 

Water table and water level: The space between soil particles on the surface of earth is called pore space. This is of two types, micro pores and macro pores. Most of the water is held in the micro pores. These pores are available for plant roots

       Surface soil pore spaces are generally filled with air and water. Water that percolates down through pore spaces of rocks is available as ground water. This ground water provides soil moisture for plants and supplements streams and lakes.

                                         

The porous rocks are saturated with water at a certain level below the surface that is called zone of saturation. The upper level of zone of saturation is called the water-table. The depth in the soil where all the pore spaces of soil particles are saturated with water is called water table. The water table reaches the surface of earth in rainy seasons, near rivers, lakes and swamps. It is deeper on hilltops, in dry areas and in areas of low rainfall. The various factors tend to lower the water at any given place are: Scanty rainfall, Excessive use of ground water, Cultivating of trees.

 

Water pollution: An undesirable change in the physical, chemical or biological qualities of water due to the addition of harmful and toxic substances making it unfit for drinking and for the use of aquatic life is called as water pollution.

          Pollution of water is one of the most serious environmental problems of the world. The main sources of water pollution are sewage, industrial wastes, synthetic soaps and detergents, fertilizers and pesticides, petroleum oil and heat. The various harmful effects of water pollution are

i.                   Spread of various diseases like jaundice, typhoid, cholera, hepatitis, dysentery etc.

ii.                Destruction of useful microorganisms due to addition of industrial wastes and chemicals with water.

iii.              Reduction of dissolved oxygen due to the excessive growth of algae as a result of extra loading of nutrients in the water body which leads to the death of aquatic life (Eutrophication).

 

Rain water harvesting: It is the technique used to capture and store rain water by making special water harvesting structures so that there is an increase in the recharge of underground water resources. Rain water harvesting can be done by digging out wells, by constructing percolation pits, by constructing check dams and through lagoons as well.

 

Soil: Soil can be defined as the uppermost crust of earth mixed with organic material and in which animals and microorganisms live, and plants grow. The word soil is derived from a Latin word solum meaning ground. It is a stratified mixture of inorganic and organic materials, both of which are products of decomposition. Formation of soil takes place by interaction between the physical and biological components. Inorganic or mineral constituents are derived from the soil forming rocks, by fragmentation or weathering. Rocks are affected by the action of rain, wind and temperature. This is physical weathering. Lichens and mosses grow on rocks also causing weathering. The organic component of the soil is formed either by microbial decomposition of dead remains of plants (litter) or animals, or through metabolic activities of living organism present in the soil.

 

 

Components of soil:- The important components of the soil are

i.                    Inorganic material derived from parent (material) rocks.

ii.                 Organic material derived from dead and decayed materials.

iii.               Biological system - such as bacteria, fungi, algae, protozoa and other soil animals such as nematodes, earthworms etc.

iv.                The air and water occupying the pores between the soil particles that are loosely packed.

 

Types of soil:- Soil is classified based on nature and composition, into the following:

i.                    Alluvial soil - rich in loam and clay.

ii.                  Black soil - mostly made of clay.

iii.                Red soil - sandy to loam.

iv.                Mountain soil - stony, sandy soil.

v.                  Desert soil - sandy and poor in organic carbon.

vi.                Laterite soil - porous clay, rich in iron and aluminium hydroxides.

 

Soil formation: Soil formation is the process by which rocks are broken down into progressively smaller particles and mixed with decaying organic material. Bedrock begins to disintegrate as it is subjected to freezing-thawing cycles, rain, and other environmental forces. The rock breaks down into parent material, which in turn breaks into smaller mineral particles. The organisms in an area contribute to soil formation by causing it to disintegrate as they live and adding organic matter to the system when they die. As soil continues to develop, layers called horizons form. The A horizon, nearest the surface, is usually richer in organic matter, while the lowest layer, the C horizon, contains more minerals and still looks much like the parent material. The soil will eventually reach a point where it can support a thick cover of vegetation and cycle its resources effectively. At this stage, the soil may feature a B horizon, where leached minerals collect.

Soil erosion: The removal and transportation of top layer of soil from its original position to another place with the help of certain agents such as strong winds and fast running rain water, is called as soil erosion.  The major causes of the soil erosion are strong winds, heavy rains, improper and suspended cultivation, human actions, dust storms, frequent floods etc. The various measures that can prevent the soil erosion are.

i.                    By protecting the soil from the impact of rainwater.

ii.                  By contour bounding, we can prevent water from moving down the slopes.

iii.                By slowing down the water when it flows along the slopes. This is done by 'gully plugging'.

iv.                By encouraging more seepage of water in the soil.

v.                  By increasing the size of soil particles.

vi.                By growing more vegetation to cover the soil and by reducing the wind velocity around the soil

 

Soil pollution: The contamination of soil (or land) with solid waste, chemicals (through industrial wastes or acid rain), fertilizers and pesticides, reducing its fertility is called as soil pollution or land pollution. The main sources of soil pollution include solid wastes, chemicals (directly through industrial wastes or indirectly through acid rain), excess of fertilizers and pesticides used in the crop fields. The various harmful effects of soil pollution are

i.                   Soil pollution by chemicals, due to dumping of industrial wastes or acid rain, reduces the fertility of soil leading to reduction in crop yields.

ii.                Excessive use of fertilizers and pesticides also pollutes the soil, affects its fertility and subsequently reduces the crop yield. The soil, thus, may become acidic or alkaline.

iii.              Harmful non-biodegradable chemicals can enter the food chains, biomagnifies and affect various biotic components including man.

 

Minerals:- Earth's crust is rich in inorganic materials. It includes ores, that are used on a large-scale to yield metals such as iron, aluminium, copper, tin, nickel, silver, gold, platinum etc. These minerals are very useful in industrial and technological growth. Some of the metals are used as catalysts, for e.g., vanadium, tungsten and molybdenum. Some of the non-metallic materials (minerals) such as sand, fluxes, clay, salt, sulphur, phosphorus, diamonds, gems, coal and by-products of petroleum (petrol, kerosene, lubricants) are vital to industrial growth.

The mineral resources are not renewable. Mineral deposits are formed slowly over millions of years and once used, cannot be regenerated. Coal, petroleum, iron, gold, aluminium, copper are the important natural resources. Petroleum products also called fossil fuels are widely used in agriculture, transportation and industry. In the modern technological world, the minerals like iron, steel, aluminium, glass, cement, sand, gravel, bricks etc. are used in the field of medicine and surgery, space technology, agriculture and its allied fields, buildings, transportation and in national defence. Atomic energy is produced by metals such as uranium and thorium. Thus, mineral resources play a significant role in the economy of a nation.

 

Biogeochemical cycles: The nutrient elements derived from the earth by the living organisms for use in their growth and metabolism are called as biogeochemicals. These materials are continuously recycled in nature. The movement of these nutrient elements through the living and non living components of the biosphere or any other ecosystem is called as biogeochemical cycle or cycle of matter. It includes water cycle, oxygen cycle, nitrogen cycle and carbon cycle.

 

Oxygen cycle: Oxygen is present in water and forms 20% of atmosphere. All living things need it for respiration. Oxygen content of atmosphere has remained constant for last several million years. Most of the oxygen lost is replenished by the plants through the process of photosynthesis. Suring photosynthesis carbon dioxide is used by the plants to form food along with release of oxygen. The oxides can be reduced both chemically and biologically to produce oxygen. Microbial oxygen can also occur in the biosphere.

          Due to the burning of materials, oxygen form carbon dioxide. When oxygen combines with nitrogen, it forms oxides of nitrogen, amino acids, proteins etc. These compounds on breakdown release the oxygen in atmosphere.

                              

 

Water cycle: Water is the most abundant (about 60% -90%) component of protoplasm. It acts as a habitat for hydrophytes and many aquatic animals, a good ionizer, good solvent, temperature buffer and a good medium for transport of materials. It also helps in digestion of organic compounds and in photosynthesis of plants. There are two types of water cycle i.e. Global and biological water cycles. 

a.    Global water cycle: It does not involve living organisms and involves the interchange of water between the earth’s surface and the atmosphere via the processes of precipitation and evaporation. Ocean is the biggest store house of water of water. Evaporation involves the conversion of liquid and solid forms of water into vapours and later forms the clouds. Precipitation involves the rainfall, hail, snow, etc. Energy for global water is provided by the sunlight in the form of heat.

b.    Biological water cycle: It is the interchange of water between abiotic and biotic components of environment e.g., the plants absorb water from bodies and soil while lose most of the water by the process of transpiration through their leaves. Animals consume water from water bodies or the food ingested, while release the water through the process of respiration and excretion.

c.      

Water vapours in the atmosphere

Rains

Evaporation by transpiration

Evaporation from animal bodies

Evaporation from land

River, lakes and oceans

Ground water table

Clouds

 

 

 

 

 

 

                            

 

 

 

 

                                        Block diagram of Water cycle

 

Nitrogen cycle: Nitrogen is essential component of amino acids, proteins, enzymes and nucleic acids of the protoplasm. Reservoir pool of nitrogen is atmosphere which contains about 78.62% of nitrogen in gaseous state. But it cannot be used directly and is changed into nitrates and nitrites through a natural process known as nitrogen cycle.  The nitrogen cycle occurs in six steps.

i.       Free nitrogen of air is converted to nitrates and ammonia by the nitrogen-fixing bacteria in soil and by the blue-green algae in water. This process is called as nitrogen fixation.

ii.    Green plants get their nitrogen from soil, in the form of nitrates. They assimilate this form of nitrogen and convert it to amino acids and proteins which gets incorporated into the living protoplasm.

iii.  Through trophic levels, the heterotrophs get their nitrogen from plant foods.

iv.  Animals give out ammonia, urea and uric acids as major excretory products. All of these are nitrogenous compounds. They are again converted to ammonia by bacterial activity. Also the death and decay of plant bodies releases ammonia. This process is called as ammonification.

v.    Ammonia is converted to nitrites and nitrates by the soil bacteria. These are the nitrifying bacteria and the process is called as  nitrification. These saltsof nitrogen may again be cycled into green plants, as they absorb it from the soil.

vi.  Part of the nitrites and nitrates of the soil are acted upon by another class of bacteria called the denitrifying bacteria which release the free nitrogen back into the air. This process is called dentrification.

                      

 

Carbon cycle: Carbon is present in the atmosphere as carbon dioxide (0.03 – 0.04%) in the gaseous form. Oceans have large deposits of carbon as carbonates and various salts of bicarbonates, which dissociate to give carbon dioxide that remains dissolved in water. Even fresh water has dissolved carbon dioxide in it. Another important source of carbon is deep under the soil in the form of peat, coal, petroleum, oil and gas. In the living organisms, carbon is present in carbohydrates, proteins and fats. The primary withdrawal of carbon as carbon dioxide  from the atmosphere pool is by processes of respiration, decomposition, combustion of fuels, and chemical reactions that give off carbon dioxide from carbonates or limestones. Occasional eruptions of volcanoes also add to the carbon content of atmosphere as carbon dioxide. Thus there is one major route of utilization, but several for replenishing carbon dioxide back to the atmosphere.

                      

Green house effect: The greenhouse effect refers to the way in which gases in the Earth’s atmosphere warm the Earth like the glass roof of a greenhouse—by letting sunlight in but keeping the reflected heat energy trapped inside. These naturally occurring gases, notably carbon dioxide and water vapour are called greenhouse gases.

       The atmosphere cover around the earth acts like glass walls of the green house. It allows solar radiations to pass through it to strike the earth surface. However, it prevents the long wave infra red radiation (reflected back from earth) to escape into the space. Gases like carbon dioxide (CO₂), methane (CH₄), chlorofluorocarbons (CFCs), nitrous oxide, ozone etc. are called green house gases. Out of these CO₂ is the most important green house gas. Man is adding large amounts of CO2 and CH₄ to the atmosphere by burning of fossil fuels in homes, industries, automobiles, burning associated with agricultural practices as well as by deforestation. Methane is also added to the atmosphere by the decay of vegetation matter in marshes, paddy fields, and biogas plants. These green house gases trap the heat reflected by the earth. This heat up the atmosphere and increases the earth’s temperature. This phenomenon is called as global warming which occurs due to green house effect.

 

Effects of global warming: The main effects of the global warming are:

i.       Increase in temperature of the earth even by 1^oC can lead to melting of ice present on the poles of the earth. This will result in rise of the sea level. Thus, coastal regions will be flooded or might even be submerged completely.

Increase in the temperature of the earth due to green house effect will result in changes in weather and precipitation patterns.

 

                                          TEXTUAL QUESTIONS

Q NO 1:- How is our atmosphere different from the atmospheres on Venus and Mars?

ANS:- Our atmosphere on the earth is composed of a mixture of many gases like nitrogen, oxygen, carbon dioxide and water vapour in a percentage of 78.08%, 20.95%0.03% and varied proportions respectively. But the atmosphere on the Venus and Mars majorly consist of carbon dioxide (up to 95- 97% of their atmosphere). The atmosphere on Venus and Mars does not support life, where as our atmosphere is apt for life.

 

Q NO 2:- How does the atmosphere act as a blanket?

ANS:- The atmosphere contains air which is a bad conductor of heat. The atmosphere keeps the average temperature of the earth fairly steady during the day and even during the course of the whole year. It prevents the sudden increase in temperature during the day and slows down the escape of heat into outer space during the night. This maintains a comfortable climate on the earth. So the temperature plays a very important role in climate control and act as a blanket for the earth.

 

Q NO 3:- What causes wind?

ANS:- The unequal heating of the atmospheric air causes wind. Land gets heated faster than water, therefore air over land also gets heated than the air over water bodies. This can be observed in coastal regions where during the day land gets heated faster and the air above it being warm and lighter, rises up.  Due to this a low pressure region is created .The air above water (sea) is comparatively cool and moves into the region of low pressure. This causes breeze. During the night it moves in opposite direction i.e. land to sea. So, the movement of air from one region to the other creates the winds.

The rotation of the earth and the presence of mountain ranges in the paths of wind are some of the factors which influence the winds.

 

 

Qno4: How are clouds formed?

Ans: Water gets evaporated in large amounts from water- bodies and in some amounts because of various biological activities .The hot air rises up carrying this water in the form of water vapour with it. As the air rises it expands and cools. Due to cooling the water vapour in air condenses in the form of tiny droplets .Dust or some suspended particles in air act as a nucleus for these drops to form around. This air saturated with water forms clouds.

 

Qno5: List any three human activities that you think would lead to air pollution?

Ans: The three main human activities that would lead to air pollution are:-

1. BURNING OF FOSSIL FUELS:-These fuels contain small amounts of nitrogen and sulphur. When these fuels are burnt, the oxides of nitrogen and sulphur are formed which dissolve in rain to cause acid rain. The inhalation of these gases causes respiratory problems.

2. EMISSION FROM VEHICLES:-This contains many harmful and poisonous gases like carbon monoxide (77.2%), oxides of nitrogen (7.7%) and hydrocarbon (13.7%).

3.INDUSTRIALIZATION:- Smoke which comes out of industries contains many pollutants like CO_2, CO, SO_2,H₂O, oxides of N₂ and small particles of dust, carbon , metals and even radio –active materials.

 

Qno6: Why do organisms need water?

Ans: Water is a wonder liquid essential for living beings. Organisms need water for following reasons:-

1. Water acts as a medium for all cellular processes.

2. Water helps in maintaining the body temperature.

3. Water acts as a solvent for various substances in the bodies of organisms. This helps in transportation of various materials in the body in their dissolved form.

 

 

 

Qno7: What is the major source of fresh water in the city / town / village where you live?

Ans: The major source of fresh water in the city/town/ village where we live is the underground water which is taken out with the help of bore- wells (tube wells).

Qno8: Do you know of any activity which may be polluting this water source?

Ans: Sewage from our town/ city and the waste from factories are dumped into rivers and lakes. This mixes with the ground water (if the well is not deep enough) and may pollute the water source.

 

 

Qno9: How is soil formed?

Ans: Soil is formed by the weathering of rocks for which many factors are responsible. It is formed by the action of rain, wind, temperature, plants and animals on rocks. In the beginning, the earth’s crust was made up of thick layers of rocks. These rocks were continuously heated up by the sun and cooled by the rain. The wind, water, heat and cold helped these rocks to crack and break into smaller pieces. This breaking up of the rocks went on continuously for years. After thousands of years, very fine sand, pebbles and gravel were formed. These together with the remains of dead plants and animals make up the soil that we have today.

 

Qno10: What is soil erosion?

Ans: The removal of fine particles of top soil (which is fertile) by flowing water or wind is called soil erosion.

Qno11: What are the methods of preventing or reducing soil erosion?

Ans: The methods of preventing or reducing soil erosion are:-

1. Vegetative cover: - The soil covered by plants (vegetation) does not erode easily as roots hold soil and prevent soil erosion.

2. Afforestation: - Deforestation must be reduced to prevent soil erosion and afforestation must be done so that the roots of big trees hold soil and do not allow washing away of soil. Tall trees check speed of wind and thus help in preventing soil erosion.

3. Avoid over grazing:-Overgrazing of grasslands by animals turn them barren. In the absence of grass cover soil erodes easily. So, overgrazing should be avoided.

 

Qno12: What are the different stages in which water is found during the water–cycle?

Ans:-Water is found in all the three states during the water cycle. These are:-

1.Solid:-In the form of snow, hail or sleet due to freezing of droplets of water present in the upper atmosphere.

2.Liquid:-In the form of rain water by condensation of water vapour.

3.Gaseous:-In the form of water vapour. When water evaporates from the surface of water bodies and other sources it forms water vapour.

Qno13: Name two biologically important compounds that contain both oxygen and nitrogen?

Ans: - These compounds are nitrites (NO₂^-) and nitrates (NO₃^-).These are further converted into proteins. Nucleic acids (DNA and RNA)also contain both oxygen and nitrogen.

 

Qno14:List any three human activities which would lead to an increase in the carbon-dioxide content of air.

Ans:-The three human activities which would lead to an increase in the CO₂ content of air are:-

1. Combustion of fossils fuels:-The fossil fuels (coal, petrol, diesel etc.) burn in the presence of air to provide energy and give out CO₂and water vapour.

2. Respiration:-Plants and animals release carbon dioxide during respiration. This is natural process.

3. Deforestation:-plants use atmospheric carbon dioxide for photosynthesis and release oxygen. But due to deforestation ,then tree population decreases which leads to an increase in CO₂ concentration in the air.

 

Qno15. What is the greenhouse effect?

Ans: Some gases like CO₂ and methane absorb the infra-radiation and trap the heat with in the atmosphere, preventing its escape into the space. This is just like the glass which keeps green house (for plants) warm. So, the heating of the atmosphere due to the absorption of infra-radiations by CO₂ molecules is called the greenhouse effect.

 

Qno16: What are the two forms of oxygen found in the atmosphere?

Ans: The two forms of oxygen found in the atmosphere are:-

1. O_2:- The diatomic molecule of oxygen gas in the lower regions.

2. O_3:-The triatomic molecule called ozone in the upper region of atmosphere .This prevents the earth from UV radiations.

 

Qno17: Why is the atmosphere essential for life?

Ans: The atmosphere is essential for life because:-

1. It is the reservoir of many gases which help in sustaining life, such as oxygen (for respiration), carbon dioxide(for photosynthesis in plants).

2. It maintains fairly steady temperature on the earth during the day as it prevents sudden increase in temperature.

3.Ozone layer prevents earth from UV radiations.

 

Qno18: Why is water essential for life?

Ans: Water is essential for life because:-

1.    It acts as a medium for all the life processes taking place in the cells.

2.    It maintains body temperature (by sweating).

3.    It helps in the transportation of substances in dissolved form from one part of the body to the other parts.

 

Qno19: How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?

Ans: Living organisms are dependent on the soil in many ways. Such as

1. Soil provides anchorage to plants.

2. Soil is home for a number of microorganisms e.g. earth worm, millipedes etc.

3. It provides various nutrients to plants which are essential for photosynthesis. This is how it is the medium that supports the growth of plants. 

        Organisms that live in water also depend on soil but indirectly .Aquatic green plants get dissolved minerals from water. The minerals present in the rocks or soil are supplied to water bodies through rain water and rivers etc. This continuous flow of minerals provides nutrients to organisms living in water. So it is not correct that living organisms that live in water are totally independent of soil as a resource.

 

Qno20: You have seen weather reports on television and in newspapers .How do you think we are able to predict the weather?

Ans: There are various observations that help to predict weather. Increase in temperature or decrease in temperature, a gentle breeze, strong winds, terrible storms, decrease of air and pressure and the direction of air.

 

Qno21: We know that many human activities lead to increasing levels of pollution of the air, water bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?

Ans:- Yes, isolating some human activities certainly help to reduce pollution. The pollution of air, water and soil influence the quality of life and harm the bio diversity. Burning of fossil fuels adds to air pollution .It can be minimized by using alternative sources of energy. Plant more trees to purify air. Treat the sewage before putting it into water bodies .Install the industries away from dwelling places. Use bio -fertilizers and organic manures in the fields in spite of fertilizers and pesticides.

 

Qno22: Write a note how forests influence the quality of our air, soil and water resources.

ANS:- FORESTS:- 1. They reduce soil erosion.

2. They are helpful to bring rain.

3.They increase the fertility of soil.

4.They help to retain subsoil water as roots absorb water.

5.They reduce air pollution by using CO₂ in photosynthesis.

 

IMPROVEMENT IN FOOD RESOURCES

Classification of crops based on seasons of cultivation:

i.     Kharif crops: The crops which are grown in the rainy season (or kharif season) are known as Kharif crops. These crops are cultivated between the months of June and October. Examples of kharif crops include paddy, soya bean, pigeon pea, maize, cotton, green gram, and black gram.

ii.   Rabi crops: The crops which are grown in the winter season (or Rabi season) are known as Rabi crops. These crops are cultivated between the months of November and April. Examples of Rabi crops include wheat, gram, peas, mustard, and linseed.

 

Crop variety improvement methods:                                                        

i.      Hybridization is the method by which two characteristics present in different organisms can be brought together into one organism. Therefore, a hybrid plant produced from two varieties will have characteristics from both the parent plants. Therefore, it will be able to produce nutritionally-rich grains, which can be cultivated throughout the year.

ii.    Genes are responsible for the features present in an organism. Therefore, another method to grow plants with the desired characteristics is to incorporate genes responsible for that character into plants. This method will result in the production of genetically modified plants. Therefore, crop plants that produce high yields in all regions with different conditions have to be produced.

 

Factors affecting the growth of crop plants:

Rainfall: The amount of rainfall affects the crop plants i.e., flood and drought conditions affect the growth of crop plants.

Soil condition: The problems caused by non-living factors (drought resistant, salinity resistant, flood (water-logging) resistant, heat/cold/frost resistantare termed as abiotic stress. The produced plants, which can resist them, are called abiotic stress resistant plants.

Disease: Plants are attacked by insects, nematodes, and other disease-causing microbes, which can decrease the yield. Therefore, producing plants, which can resist the attack by pathogens, is beneficial.

Improvements are aimed to maintain the quality of crop plants (nutritional factors).

 

Nutrient Management: Just as the human body needs nutrients for its healthy growth, plants also need certain nutrients for their growth. The nutrients required by plants for their healthy growth are 16 in number. They are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, manganese, copper, zinc, boron, molybdenum and chlorine.                                                         

                 Plants consume carbon element from carbon dioxide in the air, hydrogen from water, and oxygen from both air and water. The remaining elements are procured from the soil. Carbon, oxygen and nitrogen are very important because they constitute 94% to 99.5% of total plant tissue. The remaining 0.5% to 6% plant tissue is synthesized from soil constituents. These 13 nutrients have a direct influence on the growth of the plant.

On the basis of the quantities required, the various nutrients needed for plant growth can be classified into two groups.

Micronutrients: Some nutrients which are required by plants in small quantities and are called micronutrients. The micro-nutrients required for the growth of the plant are: Iron, Manganese, Copper, 

Zinc, Boron, Molybdenum, Chlorine.

Macronutrients: Some nutrients which are required by plants in larger quantities are called macronutrients. The macro-nutrients required for the growth of the plant are: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, and Sulphur.

 

Manures: Manure is decomposed animal and plant waste. It increases the water-holding capacity of soil. Manure is a source of many plant nutrients. It is composed of organic matter and minerals. Ammonia, nitrate, organic substances, etc. are predominant organic matters found in manures. Manures are mostly composed of micronutrients such as zinc (Zn), manganese (Mn), copper (Cu), magnesium (Mg), sodium (Na), etc.

They supply nutrients to the soil. Since the manure contains a lot of organic matter, it increases the water holding capacity in sandy soils and drainage in clayey soils. Organic manures provide food for soil organisms like earthworms which are responsible for improving soil quality. Manures can be classified as compost and green manure based on the kind of biological material used.

 

Compost: This consists of a variety of farm wastes such as farm weeds, straw, sugarcane refuse, rotting vegetables, kitchen wastes, crop stubble, ground nut and rice husk.                                                        Composting is a biological process in which aerobic and anaerobic microorganisms decompose organic matter. A trench of suitable size 4-5 m long, 1.5 to 1.8 m broad and 1.0 to 1.8 m deep is dug. A layer of well mixed refuse of about 30 cm thickness is spread in the pit. Slurry of cow dung, earth and water is poured over this layer to keep it moist. Another layer of the mixed refuse is spread in the pit till the heap rises to a height of 45 to 60 cm above ground level. Finally the top is covered with a thin layer of mud. After three months of decomposition the layers are well mixed and covered again. Three months later the compost is ready to be used in the fields.

 

Fertilizers:Fertilizers are plant nutrients, which are commercially available. They can be organic or inorganic in nature. They ensure healthy growth and development in plants by providing them with nitrogen, phosphorus, potassium, etc.However, addition of fertilizers to soil requires special guidelines to be followed (such as dosage, time, post addition precautions, etc.).

 

Advantages of fertilizers:

·         They are mostly inorganic compounds, which can readily dissolve in water. They are easily available for plants.

·         They are a good source of nitrogen, phosphorus, and potassium. However, they are good only for a short term use.

Disadvantages of fertilizers:

·         They get washed away because of irrigation. Hence, they are a cause of water pollution. Continuous use of fertilizers causes harm to useful or symbiotic microorganisms living in soil.

·         They can also result in the reduction of soil fertility.

·         They cannot replenish the organic matter of soil.

 

Irrigation: Farmers supply water to their agricultural lands by using ground water or from a nearby reservoir. The method of providing water is known as irrigation. Irrigation is the process in which water requirement, usually for agricultural activities, is met from sources other than rain water.

Types of irrigation systems:

1.      Dug wells and tube wells:- These are used to supply water in crop fields. Tube wells are used to pump up the ground water and to release it in fields as per the requirement.

2.      Canals:-  Canals are man-made water channel systems, which are used to deliver adequate water to the fields. Canals are connected with water reservoirs, or rivers to distribute water in the fields.

3.      River lift system:- River water is directly drawn from the river and is supplied to irrigate fields closer to the river. This is because in some regions, canals are irregular and insufficient because of low water levels in the river.

4.      Tanks:- These are small, water storage reservoirs. These are helpful in delivering water in smaller areas.

Some advantages of the irrigation system.

·         It increases crop productivity.

·         It ensures continuous supply of water to fields.

·         The dams stop the flowing water and reduce soil erosion.

·         It increases agricultural practice in regions with low rainfall.

·         It controls flood by diverting excessive rain water into storage reservoirs.

 

Cropping pattern: Farmers often grow different crops together without any definite pattern. These methods increase the yield. Three different cropping patterns, namely mixed cropping, intercropping, and crop rotation are generally practised.

·         Mixed cropping allows two or more crops to be sowed simultaneously in the same land. Wheat and

·         gram, wheat and mustard, ground nut and sunflower etc. are some common examples of mixed cropping. In mixed cropping, crops are chosen in such a way that they require different amounts of minerals.

·         Intercropping allows farmers to grow two or more crops simultaneously in the same field in a definite pattern. For example, cauliflower and chilli plants are grown together in alternating rows. To ensure the maximum utilization of nutrients applied, crops are selected in such a way that their nutrient requirements are different. Other examples include soyabean and maize, finger miller (bajra) and cowpea (lobia) etc.

·         Crop rotation is the practice of growing two or more varieties of crops in the same region in sequential seasons. A common example of crop rotation is to cultivate maize followed by soyabean. This system also helps in preventing crops from pests and diseases. The crops selected, vary in nutrient requirements. This ensures complete and uniform utilization of nutrients.

 

Crop protection: Crops are affected by pests and a large number of weeds in fields. Uncontrolled growth of weeds and pests reduce productivity. Also, after harvesting, the produce is still at danger of getting spoilt by various biotic and abiotic factors. Therefore, these factors must be controlled to prevent loss.

 

Factors that affect crop plants and measures used to control them.

·         Weeds are plants that grow in cultivated fields along with the crop plant. They compete with the crop plant for nutrients, light, and space. As a result, the crop plant gets lesser nutrient, light, and space. This reduces the productivity of crop plants. Xanthium (gokhroo), Parthenium (gajar ghas), Cyperinus rotundus (motha) are some examples of weeds.

·         Pests are generally insects. They destroy crops by the following methods:

o    Sucking the cellular sap from various plant parts

o    Cutting the roots, stem, and leaves of plants

o    Boring into stems and fruits

·         Micro-organisms or pathogens cause diseases in crop plants. Pathogens can be bacteria, fungi, or virus. These pathogens are generally transmitted through soil, water, and air.

 

Disease control: Plants often get infested with disease causing pathogens. The entire crop can be destroyed if they are not controlled in time. Pathogens are transmitted byseed and soil, water, air.

Seed soil and water  borne diseases mostly attack roots and plant stem. Air borne diseases attack all aerial parts of the plant i.e. leaf, flower and fruit. Seed and soil borne diseases can be controlled by treating the seed and soil. Air borne diseases can be controlled by treating the infested parts with fungicide spray.

 

Weed control: Weeds are unwanted plants that grow in the fields where crops grow. The growth of weeds

in fields has an adverse effect on crops because they compete with the crops for space, light nutrients and water. The yield becomes poor and so also the quality of the crop. The weed could be another crop plant or a plant of another variety of the same crop. So if a mustard plant grows in a wheat field it has grown out of place and so is considered to be a weed. Often weeds harbour many insects, pest and diseases. Warm and humid climate being more congenial for the growth of weeds, they are more during the Kharif season than the Rabi crop.

 

Scientific Storage of Grains: Besides crop production good crop management involves storage of grains before distribution. During storage grains and seeds are subjected to spoilage by various agencies. Biotic - Insects, rodents, birds, fungi, mites, bacteria. Abiotic - Moisture and temperature. The loss due to spoilage has been assessed to be to the tune of 9.3% annually.

 

Measures to prevent loss during storage:

1.      Drying: At the time of harvesting the moisture content in grains and seeds varies from 15-35%. Moisture content in grains and seeds must be reduced to below 9% for their safe storage. To achieve this seeds have to be spread out and dried in the sun before drying in the shade. Mechanical hot air driers could also be used.

2.      Hygiene: Granaries, godowns and stores should be well cleaned before stacking fresh grains. Any refuse, dirt, cobwebs and husk of the previous grain should be swept. Before reusing old gunny bags, they should be turned inside out, dusted thoroughly, exposed to sun and fumigated.

3.      Prophylactic treatment: As a preventive measure godowns should be treated with insecticides and pesticides. Gunny bags should also be sprayed. Grains that have to be used for seed purpose must be mixed with fungicide and insecticide.

4.      Modern storage structures: Research organizations have developed improved storage structures which have proved comparatively safe for the storage of grains. In these structures, temperature, moisture, oxygen and carbon-di-oxide can be adjusted to protect the grains. Pest control

5.      Chemical control: Spraying of BHC wettable power, pyrethsum and malathion at 3 weeks interval can be done as a prophylactic treatment of the surface area of the store house.

6.      Fumigation: Fumigants are chemicals that can exist in sufficient concentration to be lethal to pests. The following are well known fumigants.Aluminum phosphide tablets (black poison), Methyl bromide, Ethyl dichloride carbon tetrachloride (EDCT)

7.      Plant products: Often a small quantity of vegetable oil or mineral oil is added to grains of legumes to protect them from insects. The treatment prevents laying of eggs, reduction in egg hatching and prevention of larval development. Some of the plant products used for this purpose are neem kernel powder, crushed pepper etc.

 

Crop Rotation: The growing of different kinds of crops on a piece of land in a pre-planned succession is known as crop rotation. In the rotation of crops, leguminous crops like pulses, beans, peas, groundnut are sown in-between the seasons of cereal crops like wheat, maize and pearl millet. The leguminous plants are grown alternately with non-leguminous plants to restore the fertility of the soil.

 

Advantages of crop rotation: some of the advantages of crop rotation are

1.      Rotation of crops improves the fertility of the soil and hence, brings about an increase in the production of food grains.

2.      Rotation of crops helps in saving on nitrogenous fertilizers, because leguminous plants grown during the rotation of crops can fix atmospheric nitrogen in the soil with the help of nitrogen fixing bacteria.

3.      Rotation of crops helps in weed control and pest control. This is because weeds and pests are very choosy about the host crop plant, which they attack. When the crop is changed the cycle is broken. Hence, pesticide cost is reduced.

4.      Crop rotation adds diversity to an operation.

 

Animal husbandry: It is the science of managing animal livestock. It involves feeding, breeding, and controlling diseases in farm animals. Animal husbandry involves the rearing of animals like cattle, poultry, and fish to obtain desired products from them.

 

Cattle farming: Many products like curd, cheese, butter etc. are produced in a dairy. A dairy farm rears cows and buffaloes, which provide milk, the primary material for all these products. In India, two different species of cattle are widely reared, Bos indicus (cow) and Bos bubalis (buffalo). The purpose of cattle farming is usually for the production of milk and labour in agricultural fields. Female dairy animals used to obtain milk are known as milch animals. The production of milk depends upon the lactation period. Male animals are engaged in agricultural fields for labour work like carting, irrigation, tilling etc. Cattle used for labour is called draught animal.

 

Breeding cattle: Choosing improved breed is another element of cattle management. Hybrid cattle breeds are produced for improved productivity. For example, two breeds with required qualities are cross-bred. Exotic or foreign breeds like Jersey, Brown Swiss etc. are selected for increased milk production. Local breeds like Red Sindhi, Sahiwal etc. are highly resistant to diseases. These two breeds are crossed to produce a hybrid breed, in which both the characteristics are available. Therefore, the offspring not only produces more milk, but is also more resistant to diseases.

 

Feeding cattle: The cattle should be provided with healthy and nutritious food. Their food requirements can be classified into two types based on:

• General/maintenance requirement: It provides nutrition to support a healthy life.
• Milk producing requirement: It provides nutrition for lactation.

• Cattle should be provided with a well-balanced diet which contains Roughage which largely consists of fibre, Concentrates, Additives which promote their health and milk production

 

Heeding cattle: A variety of diseases affect cattle. Parasites are the common cause for these diseases. Parasites present on the body surface (called external parasites) of an animal cause skin diseases. The internal parasites include worms (in the stomach and intestine) and flukes (in the liver).Cattle are also affected by viral and bacterial diseases. However, vaccination can be given to prevent viral and bacterial diseases.

 

Poultry farming: Poultry farming involves large-scale rearing of poultry birds. Poultry farming is undertaken to meet an increased demand of eggs and chicken. It deals with the management of domestic fowl in order to improve the quality and productivity of egg and chicken. Improvement in poultry variety is achieved through the process of hybridization or cross breeding.

 

Egg and Broiler production: Broilers are reared for meat. They are fed with protein and vitamin-rich supplements (mainly vitamin A and vitamin K), with adequate amounts of fat. This helps in maintaining their feather and carcass quality. It also reduces mortality rate. Nutritional requirements are different for egg and meat production. Food supplemented with respective nutritional needs is provided. Housing of the two types also varies. For good production of poultry, proper management techniques should be followed. Regular cleaning of the farm is of utmost importance. Maintenance of temperature is also required.

 

Diseases of poultry:

Poultry birds suffer from a variety of diseases which are caused by bacteria, virus, fungi, or parasites. They also suffer from nutritional deficiencies. These diseases in the poultry birds can result in economic losses. Preventive measures include providing a clean housing area, with regular sanitation, and spraying of disinfectants. Vaccination also prevents the spread of infectious diseases.

 

Disease and control in poultry: Poultry fowls suffer from a number of diseases caused by virus, bacteria, fungi, parasites and nutritional deficiencies. Some of the diseases are fowl cholera, salmonellosis, fowl fox and parasitic infestations like roundworm, tapeworm and threadworm. Appropriate vaccinations and other preventive measures can prevent loss of poultry during an outbreak of disease.

 

Fish farming: Fish farming is the practice of raising fish population commercially. It involves the production of aquatic animals, which are of high economic value like prawns, fishes, lobsters, crabs, shrimps, mussels, oysters etc.

There are two ways of obtaining fishes:

• Capture fishing is the process of obtaining fishes from natural resources
• Culture fishery is the practice of farming fishes

Farming can be done in both fresh water (such as rivers, ponds etc.) and marine ecosystems.

 

Marine fisheries

In India, marine fishery is carried out along the 7,500 km coastline and the deep seas beyond it. Fishing is done using fishing nets and boats. The amount of fishes caught can be increased by locating schools of fishes using satellites or echo sounders. Some examples of marine fishes include mackerel, tuna, sardine, pomfret, and bombay duck. Some varieties of marine fish are of high economic value and include finned fishes (like pearl spot, bhetki, mullet etc.) and shelled fishes (like prawns, mussels, oysters etc.).The cultivation of marine organisms for a commercial purpose is known as mariculture.

 

Inland fisheries

Canals, ponds, and rivers are some freshwater resources. Brackish water resources are generally found where seawater and fresh water occur together. It includes estuaries and lagoons. Fresh water fisheries and brackish water fisheries are called inland fisheries. For example, catla feed on the surface of water, rohu are middle zone feeders, mrigal and common carp are bottom feeders, and grass carp feed on weeds. This ensures complete utilization of food resources in the pond. Such a system increases the fish yield.

 

Disease and control in fishes:- The main causes for disease in fishes are viruses and bacteria. IPN (Infectious Pancreatic Necrosis) and VHS (Viral Haemorrhagic Septicaemia) are well known diseases. Pollution of water causes great harm to the fish population. Fertilizers, pesticides, effluents and chemical wastes from factories contribute largely to pollution of water bodies. In order to maintain the population of fish, regular monitoring of the oxygen level, carbon dioxide level and pH of the water is important.

 

Apiculture: The practice of bee keeping is known as apiculture, and the bee farms are known as apiaries. Bee keeping industry has become an additional income generating activity among farmers as it requires low investment. Moreover, beehives can also be used as a source of wax. Bee wax is used in several medicinal preparations.

TOPIC:-  DIVERSITY IN LIVING ORGANISMS          

                                (BIOLOGY)

BIO-DIVERSITY:-Variability among living organisms is known as biodiversity.   

CLASSIFICATION:- Classification of organisms may be defined as a system of

arrangement of organisms into different groups and sub-groups on the basis of their similarities, differences and relationship.

Classification of organisms is also known as taxonomy. It has the following advantages.

1. Classification makes the study of a wide variety of organisms convenient and

easy.

2. It is not possible for man to know about all the organisms but the study of a

few representatives from each taxonomic group gives a general idea of all life

forms at a glance.

3. Classification also reveals the interrelationship among different groups of

organisms.

4. Correct identification of an organism and its placement in a definite taxonomic

group is the basic requirement of various branches of biological sciences.

Thus, classification of organisms provides a base for the development of other

biological sciences.

 

BASIS OF CLASSIFICATION:-

Classification can be done on the following basis:-

1. Cells are prokaryotic or eukaryotic:- Organisms may be grouped into two

broad categories on the basis whether they possess prokaryotic cells or

eukaryotic cells. In case of prokaryotic cells the nuclei and other organelles

are not clearly demarcated. The eukaryotic cells, on the other hand, have

membrane-bound organelles, including a nucleus.

2. Unicellular or Multicellular:- Many organisms are unicellular, i.e. made up of only one cell, e.g. Amoeba. Others are multicellular, i.e., cells group

together to form single organism (e.g., insect). In case of multicellular

organisms the different groups of cells carry out specialized functions

3. Organism is Autotrophic or Heterotrophic:- Green plants

perform photosynthesis an synthesis their own food. Animals cannot perform

photosynthesis. They get food from outside.

4. Body is differentiated or non- differentiated:- Grouping of organisms may be done on the basis of body organization. For example, plants possess stem, root and leaves. Similarly, the animals possess specialized organs to perform different

function. The characteristic based on body design used for classification of

plants is quite different when used for classifying animals.

 

Systems of classification:- R H whittaker in 1969, suggested five kingdom classification on the basis of:- (i) presence or absence of a nucleus (ii) unicellular or multicellular and (iii) mode of nutrition.

He proposed five kingdoms:

1. Monera, 2. Protista, 3. Fungi, 4. Plantae and 5. Animalia.

1. Monera:- these organisms do not have a defined nucleus or organelles, nor do any of them show multi-cellullar body designs. They show diversity based on many other characteristics. Some of organisms of this group are either autotrophic or

heterotrophic. This group includes bacteria, blue-green algae or cynobacteria and

mycoplasma.

2. Protista:- This group includes many kinds of unicellular eukaryotic organisms.

Some of these organisms use cilia or flagella for moving around. Their mode of

nutrition can be autotrophic or heterotrophic. Examples are unicellular algae,

diatoms and protozoans.

3. Fungi:- these are heterotrophic eukaryotic organisms. They are saprophytes and thrive on decaying organic material. They have cell-walls made of chitin. Examples are yeast and mushrooms.

4. Plantae:- these are multi-cellular eukaryotes with cell walls. They are autotrophs and used chlorophyll for photosynthesis. All plants are included in this group.

5. Animalia:- these includes all multi-cellular organisms. They are heterotrophs.

NOMENCLATURE:-

Naming a correct scientific name to an organism or a taxon is called nomenclature.

It involves the principals governed by set rules formulated by internationals bodies

so that a particular organism or taxon is known by its specific name throughout the

world.

 

 

 

BINOMIAL NOMENCLATURE:-

According to the binomial system of nomenclature, the scientific name of an

organism consist of two separate components – first on designates the genus

(generic name) and the second one designates the species (specific name). For

example, the scientific binomial name of human species is Homo sapiens, where first name Homo is generic and the second name sapiens is a specific. Homo sapiens are understood to mean humans all over the world. Since this system of naming organisms gives two names to an organism, it is known as a binomial

nomenclature.

 

Various ranks used in classification (Hierarchy of classification):-

In classification, the organisms that closely resemble one another are placed in a

group. These groups are further placed in large groups on the basis of close

similarities. The larger groups are again placed in still larger grouping levels or

ranks in classification are known as categories. Each category has its specific name.

There are seven major categories:

1. Species 2. Genus 3. Family 4. Order 5. Class 6. Phylum/division 7. Kingdom.

1. Species:- Species is the lowest category regarded as basic unit classification. It

is a group of similar individuals which resembles with each other in

morphology, breed among themselves but not with others and probably

descended from a common ancestor.

2. Genus:- A genus is a group of closely resembling species having a common

ancestry. A;; the species in a genus show similarities in broad features of their

organization but differ in minor details.

3. Family:- A family represents a larger group of closely related genera. It is

composed of one or more genera.

4. Oder:- An order is a group of closely related families.

5. Class:- A class is a group of related orders.

6. Phylum/Division:- Phylum (in case of animals) or Division (in case of plants) is

a group of related classes.

7. Kingdom:- Kingdom is the highest category in biological classification. It is

group of phyla (in case of animals) or divisions (in case of plants).

 

Mainly the following rules apply to scientific names:-

They were initially framed by Linneaus. And were revised in 9th and 20th century

through international code of Botinical Nomenclature (ICBN) and international code of Zoological nomenclature (ICZN). They are as followes:

1. Each organisms has a distinct scientific name having a words, generic and

scientific.

2. The generic and specific words should not have less then three letters or more

than 12(twelve) letters.

3. The generic name is written first. It is like a noun . Is first letter is always

capital.

4. The specific word is written after the generic name, It starts with small letter.

5. The name of the discoverer is appended to the two-word scientific name either

In full or abbreviate form e.g., mangifera indica . L(L stands for Linnaeus).

6. Scientific name is printed in italics hand written name is underlined.

7. When an organism has been given different scientific names by different

workers the “law of priority” is followed that is old valid name is accepted and

others rejected.

 

KINGDOM PLANTAE:-

Characteristics features of kingdom plantae.

i) They are made of eukaryotic cells.

ii) They are multicellular.

iii) The cells have wall made of cellulose.

iv) They store carbohydrates such as starch.

v) Some cells (except in some parasites) contain chloroplast.

vi) The organisms feed by photosynthesis.

                                       

  PLANT KINGDOM

According to the classification proposed by eicher, plant kingdom is divided in to two Sub-kingdoms i.e crypotogamae and phanerogamae.

CRYTOGAMAE:- These are known as lower plants. The flower/seed are

absent and hence these are considered to have hidden reproductive organs. It

is categorized into 3 divisions.

1).THALLOPHYTES:- Thallophytes have a body which is not differentiated into stem, root and leaves. This kind of undifferentiated body is called thallus, hence the name thallophytes.

It has the following characteristics.

(1). The plant body is thalloid i.e., cannot be differentiated into stem, root and

        leaves.

(2). The vascular system is absent in such plants.

(3). The reproductive organs are single called and there is no embryo formation.

       Thallophyta is further subdivided into:

(A) Algae

(B)Fungi

(C) Lichens

(A). ALGAE:- They generally include aquatic plants. Some 20,000species of algae

are known. The main characteristics are as under :

1. They are generally chorophyllous thallophytes in which vascular tissues are

     absent.

2. The plant body is thalloid i.e., cannot be differentiated into root, stem and

     leaves.

3. They are found in fresh water resources as well as in sea water.

4. They are autotrophic because of the presence of chlorophyll in leaves. The

     reserve food is generally a carbohydrate.

5. The cell wall is double layered. The outer layer is made of pectin and inner

     layer is made cellulose.

6. They may be unicellular as well as multicellular.

7. A few members such as chlamydomonas are motile.

8. They reproduce by vegetative, asexual as well as sexual methods. The sex

    organs are unicelled and lack a sterile covering around them.

Example: oedogonium, Chara, Ectocarpus, Chlamydomonas, Ulothrix etc.

(B).FUNGI: it is a large group of over 90,000 species. They show the following

characteristics :

1. They are achlorophyllous and non-vascular plants.

2. The plant body may be unicelled or thalloid, made of branched or unbranched   

    filamentous structures, the hyphae.

3.The network of hypae is called mycelium.

4.The hyphae may be aseptate or septate and each cell may be uni-or 

   multinucleale.

5. The cell wall is made of chitin or fungal cellulose.

6. They show heterotrophic mode of nutrition.

7. The reserved food is in the form of glycogen and oil globules.

8. They reproduce by asexual or sexual methods.

9. The sex organs are unicelled and lack a sterile covering around them. The higher  

    forms lack distinct sex organs.

Example : Rhizopus, Yeast, Agaricus (Mushroom) etc.

 

(C) LICHENS:- They represent a symbiotic association of a fungus and a alga in

which two organisms are so closely associated with each other as to form a single

plant. They are show growing long lived plants. The commonly grow on leaves, tree trunks, old logs, soils and rocks. Some lichens occur in extreme conditions of cold, humidity and drought. In these plants the algal part prepares the food and the fungal part shows reproduction. Thus, their association is mutualistic.

(2). BRYOPHYTES:- Bryophytes are simple terrestrial plants.

They have over 25,000 species. They show the following characteristics:-

1. They lice in damp and sandy habitates hence they are called amphibians of

the plant kingdom. They are aften found to grow during rainy season forming

green carpets or mats on damp soil, rocks, walls, tree trunks etc.

2. The vascular tissues are absent.

3. The roots are absent and instead rhizoids are present. Rhizoids may be

    unicellular or multicellular.

4. The reproduction takes place by vegetative or sexual methods.

5. The vegetative reproduction is quite common through fragmentation tubes,

    gemmae, buds, adventitions branches etc.

6. They show distinct alternation of generation.

Example: Riccia, Marchantia, Funaria (Moss).

(3). PTERIODOPHYTES:- These are the oldest vascular plants this includes the

forms. The important characteristics are.

1. The plant body is differentiated into roots, stem, and leaves.

2. The dominant phase or plant body is a sporophyte.

3. They are seedless vascular plants and hence called vascular cryptogams.

4. The gymetophyte is small or inconspious.

5. The sex organs are multicellular.

6. The fertilization requires water medium results in the formation of zygote.

7. They show distinct alternation of generation.

Example : Selaginella, Adiantum, Dryopteris.

 

PHANEROGAMAE:- They are seed bearing plants. The plants body is differentiated into ture stem, leaves and root. A well developed vascular system is presents in phanerogames. Sex organs are multicellular.

On the basis of fruit formation, they are classified into two subdivisions.

(a) Gymnosperms and (b) Angiospermes

 

(a). GYMNOSPERMS:- the term is made from two Greek words : gymo – means

naked and sperme means seed. The plants of this group bear naked seeds and are

usually pereneal, evergreen and woody. It has nearly 650 living species. They chief

characteristics are:-

1. They have well developed vascular tissues but lack vessels. The ‘flowers’

    compose two types of sporophylls i.e., microsporophylls and megas[orohylls.

2. The pollination is anemophilous and the fertilization does not require water

    medium. There is formation of pollen tube. (Siphonogamous)

3. The zygote develops into an embryo.

4. Since the ovules are not covered by a cattel there is no fruit formation. They

    are naked.

Example : Cycas, Pinus and Emphedra etc.

 

(b). ANGIOSPERMS:- The word is made from two Greek words: anger means

covered and sperma means seed. The seeds develop inside an organ which is

modified to become a fruit. These are also called flowering plants. They are most

abundant and conspicuous plants with about 2,00,000 species. The general

characteristics are.

1. They are usually terrestrial plants. The plant body is sporophytic.

2. The plants may be herbaceous or woody. They may be annual, biennial or

     perennial.

3. A well developed vascular system is present in them. The xylem has vessels.

4. The angiosperms are characterized by the presence of the double fertilization

    forming a zygote and the primary endosperm, the nutritive tissue.

5. During fertilization the non-flagellate male gametes are carried by a pollen tube

    (siphonogamous).

6. Fertilized ovules ripens into seed thus the ovary is converted into a fruit.

Example : Brassica campestris (Mustard), Pisum santivum (pea) etc.

Angiosperms are divided into Monocots and Dicots.

 

i. Monocot:- monocots bear seeds which have a single cotyledon or seed leaf . the veins on their leave are parallel to each other. Their vascular bundles are arranged in a complex manner.

Example : Palms, Bamboos, Sugar – can, rice etc.

ii. Dicot:- the seeds of dicot have two cotyledons. The veins on their leaves are like a network. Their vascular bundles are arranged in a ring. Their root system consists of a main tap root with smaller branches.

                                     

  KINGDOM ANIMALAE

Characteristics features of kingdom Animalae are:-

I. The organisms are made up of eukaryotic cells.

II. The body of animals is multicellular.

III. The cells do not contain cell wall, but contain only cell membrane.

IV. They do not perform photosynthesis but have heterotrophic nutrition.

V. They have the power of locomotion.

VI. They show increased sensitivity through the nervous system.

Basis of animal classification:- There are many features used for distinguishing broad categories of animals. These features include organization, symmetry, body cavity, number of embryonic cell layers and presence of absence of notochord.

Organization

Animals are multicellular. But their body cells may or may not be recognized

into tissues and organ systems. For example, animals such as sponges are

aggregate of cells. They are at a cellular level of organization. Human beings have

organs and systems for performing body functions and are at the organ-system level of organization.

Symmetry

Symmetry means dividing the body into equal and identical parts. Sponges

are symmetrical. Cnidaria are radially symmetrical and all other animals are

bilaterally symmetrical.

Body Cavity

Body cavity or coelom is a cavity between the body wall and the food canal. It

is absent in Acoelomates and present in Euoelomates. The body cavity of

roundworms is not true and is known as Pseudocoelom.

Embryonic layers

There are three layers of cells-ecotoderm (outer layer), mesoderm (middle

layer), and endoderm (inner layer) in the embryo which give rise to parts of the body of animals. Sponges and Cnidaria do not have mesoderm in their embryos and are called diploblastic. Others animals have three layers of cells and are called triploblastic.

 

Notochord

The notochord is a stiff rod running along the body, close to the dorsal

surface. The notochord helps to provide support to the animal. All chordates possess a notochord at some stage of their development. The notochord is absent in vertebrate animals, also termed as non-chordates.

                                       

 ANIMAL KINGDOM:-

Porifera, Celenterata,Plathyhelminthes, Nematoda, Coelomate, Annelida,, Arthropoda, Mollusca, Echinodermate, Hemichrodata, Chordata, Protochordata,, Vertebrata, Pisces, Amphibia, Reptilia, Aves & Mammalia

(1) PORIFERA:-

The word means organisms with holes. These are non-motile animals attached to

some solid support. They have holes all over the body. These holes lead to a canal which helps in circulating water throughout the body and to bring in food & oxygen. These animals are covered with a hard outside layer or skeleton. They are commonly called sponges and are mainly found in marine habitats. Example: Euplectelia, Sycon etc.

(2) COELENTERATA:-

These are aquatic animals. They show more body design differentiation. The body is made of two layer of cells; one makes up cells on the outside and the other makes the inner lining body of the body. They have a gut cavity with a single opening for food and waste material. Some of them leaves in colonies & some lives  freely. Example: hydra, Jellyfish.

(3) PLATHELMINTHES:-

These are generally called flatworms they do not have a body cavity. The body is

bilaterally symmetrical. Some of them are free, living in water and soil, but most are parasites. There are three layers of cells in them and thus are called triploblastic. They range from a few millimeters to a few centimeters in size. Reproduction is mostly sexual. Example: Planarians, Liverflukes.

 

(4) NEMATODA:-

The organisms belonging to this group are mostly parasites having selender,

elongated bodies. Tapering at each end. There body is bilaterally symmetrical and

triploblastic. These cause diseases such as elephantiasis etc. Example: Ascaris,

Lumbricoides & Wuchereria.

 

 

(5) ANNELIDA:- ‘Annelid’ means ringed. The annelids are worms with body

appearing as if made up of series of rings. Annnelids are bilateral symmetrical, coelomates & triploblastic animals. There is extensive organ differentiation. There body is segmented. Each segment posses a similar pattern of organs. These may be aquatic or terristerials and some live in tubes. Example: Earthworms, leaches.

(6) ARTHROPODA:- ‘Artho’ means joined and ‘pod’ means legs. Thus,

arthopropoda means joined legs. These are triploblastic, coelomates. They are

bilaterally symmetrical & segmented. These have an open circulatory system. The coelomic cavity is blood-filled. They possess a hard exoskeleton. Sexes are usually separate. Example : Prawns, Scorpions, Butterflies, Houseflies & Crabs.

(7) MOLLUSCA:- the mollusca are animals with reduced coelome & triploblastic

body. There is bilateral symmetry. They have an open circulatory system and kidney like organs for excretion. The body is often protected by a shell. They have a muscular foot to move. Example: Snails, Mussels.

(8) ECHINODERMATA:- ‘Echinos’ means hedgehog, and ‘derma’ means

skin. These are spiny skinned organisms. They are exclusively free-living marine

animals. They are triploblastic and have  coelomic cavity. They have peculiar water driven tube that they use for moving around. They have calcium carbonate structures that they use as a skeleton. Example: Starfish and sea urchins.

(9) PROTOCHORDATA:- these are bilaterally symmetrical, triploblastic coelomate animals. Notochord is present at some stage at some stage of their life history. These are marine animals they have a closed blood system, they have a post-anal tail. Example: Herdmania, Amphioxus.

(10) VERTEBRATA:- these animals have a true vertebral column and internal

skelton vertebrates are bilaterally symmetrical, triploblastic, Coelomic and

segmented, with complex differentiated of body tissues and organs. Vertebrates are grouped into five classes and are:-

(a). PISCES:- These are fish and live exclusively in water. Their skin is covered with scales. They use oxygen dissolved in water by gills. They are cold – blooded and their heart have only two chambers. They lay eggs. The two important classes of fishes are cartilaginous fishes and bony fishes. Example: sharks, Tuna, Rohu etc.

(b). AMPHIBIANS:- Amphibians means ‘Amphi’ ‘double’ and bias ‘life’. They are

partly adapted to live on land, and partly in water. Most amphibians lay their eggs in water. These have three chambered hearts. Respiration is through gills or lungs. Example: Frogs, Toads and salamanders etc.

(c). REPTILES:- these animals can lively solely on land and are very less dependent on water. These are cold blooded, have scales and breathe through lungs. These have three chambered heart (except crocodiles). They lay eggs covered with waterproof shells. Their skin is water proof and is covered with waterproof horny scales. Example: Lizards, Snakes, Crocodiles, and Dinosaurs.

(d). AVES:- ‘AVIS’ means birds, evolved from reptiles and have many similarities

with them. These are warm-blooded and have a four chambered heart. They lay

eggs. Birds are distinguished because their bodies are covered with feathers, and

two forelimbs modified for flight. They breathe through lungs. Examples: Cuckoo,

crow, Sparrow etc.

(e). MAMMALIA:- Mammals are warm-blooded animals with four-chambered hearts. They have mammary glands for the production of milk to nourish their young. Their skin has hairs as well as sweat and oil glands. Most mammals give birth to their young ones. Sexes are separate. Example: Man, Whale, Cat & Bat etc.

                          TEXTUAL QUESTIONS

Q NO 1:-Why do we classify organisms?

ANS: - In the living world there is a great deal of diversity. The millions of life forms (plants and animals) cannot be studied in a bulk, so classification makes the study of living forms systematic and easier. We also classify organisms due to following reasons.

Q NO 2:-Give three examples of the range of variations that you see in life forms around you.

ANS: - We see the following range of variations in life forms around us

             i.            Colour variation: - We see organisms of various colours around us. Such as many life forms are colourless or white or light coloured but others are bright coloured.

           ii.            Size Variation:-Various life forms are of various sizes which may be either so small to see from naked eye.

        iii.            Variation in life-span:-We see variations in the life-span too.

 

Q NO 3:- Which do you think is a more basic characteristic for classifying organisms?

                   i.            The place where they live.

                ii.            The kind of cells they are made of, why?

ANS: -It is  the kind of cells they are made of because the habitat cannot be the basic characteristic for classification. Many different types of organisms live in a place having lot of variation. So, they cannot be grouped as one. But cell is the basic structural and functional unit .On cellular level we can see some structural similarities and dissimilarities like presence of cell membrane, plastids, nucleus etc. and also some functions they perform So, cells are the basic characteristic for classification.     

 Q NO 4:- What is the primary characteristic on which the first division of organisms is made?

ANS: - The primary characteristic on which the first division of organisms is made is whether the organism is eukaryotic or prokaryotic and whether it is unicellular or multicellular.

Q NO 5:-On what bases are plants and animals put into different categories?

ANS: - Plants and animals are put in to different categories on the basis of their ability to produce food of their own. Plants (green) have an ability to prepare food by the process of photosynthesis but animals don’t have.

Q NO 6:-Which organisms are called primitive and how are they different from the   so-called advanced organisms?

ANS:-Some groups of organisms have ancient body designs which have not changed much are called primitive organisms. These are older organisms and have simpler body design as compared to advanced organisms. Advanced organisms are those which have acquired their particular body designs relatively recently.

Q NO 7:-Will advanced organisms be the same as complex organisms? Why?

ANS: - Yes, advanced organisms will be the same as complex organisms because there is a possibility that complexity in body design will increase our evolutionary time. In that way younger (advanced) organisms are more complex than older (primitive) organisms.

Q NO 8:-What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?

ANS:- Criterion for Kingdom Monera:- The prokaryotic organisms  i.e. unicellular organisms which do not have a membrane bound nucleus or cell organelles are classified under Monera. E.g bacteria, blue green algae and mycoplasma.

Criterion for Kingdom Protista:-The unicellular eukaryotic organisms which generally use cilia or flagella for movement are put under Protista. E.g Diatoms, unicellular algae and protozoans.

Q NO 9:- In which Kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?

ANS:- We will place that organism under Kingdom Protista.

Q NO 10:- In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?

ANS:- In the hierarchy of classification species will have the smallest number of organisms with a maximum of characteristic in common and Kingdom will have the largest number of organisms.

Q NO 11:-Which division among plants has the simplest organisms?

ANS:- The division Thallophyta.

 

Q NO 12:- How are pteridophytes different from the phanerogams?

ANS:-

PTERIDOPHYTES	PHANEROGAMS
1. They possess hidden reproductive organs such i.e. cryptogamae. 2. They have naked embryos.	1. They possess well differentiated reproductive organs. 2. Seeds consist of embryo and stored food in them.

 

Q NO 13:-How do gymnosperms and angiosperms differ from each other?

GYMNOSPERMS	ANGIOSPERMS
1. Plants bear naked seeds. 2. Do not form fruits. 3. They produce cones. 4. They are generally evergreen, woody and perennial.	1. Seeds are covered by fruit wall. 2. Fruits are formed by ripening of ovary. 3. Cotyledons are present in seeds. 4. These may be biennial, perennial, woody or non- woody.

 

 

 

 

 

 

 

Q NO 14:- How do porifera animals differ from coelenterate animals?

ANS:-

PORIFERANS	COELENTRATES
1. They have pores (Ostia) all over the body with one osculum at the top. 2. Central cavity spongocoel is present. 3. Body made up of single layer of cells. 4. Sessile i.e. fixed or non-motile animals. 5. Body vase-like branched or sac- like. 6. Water canal system for circulating water that brings oxygen and food. 7. Exo- skeleton present.	1.Pores are not present. 2. Coelenteron present in the Centre of the body. 3. Diploblastic: Body made up of double layer of cells. 4.Some live in colonies others solitary. 5. Body has tentacles and special sting-cells. 6. No such system. 7. Exo-skeleton absent.

 

Q NO 15:-How do annelids animals differ from arthopods?

ANS:-

Annelids	Arthopods
1.Long segmented body. 2. True Coelom is present but not blood filled. 3. Breathe through moist body surface. 4. Excretion through nephridia.   5. Mostly bisexual.	1.Segmented body in 2 or 3 major parts. 2. Coelomic cavity is blood filled. 3. Respiration through gills, book lungs or tracheae. 4.Excretion through malpighian tubules, or coxal glands or green glands. 5.Male and female sexes are separates.

Q NO 16:- What are the differences between amphibians and reptiles?

Amphibians	Reptiles
1.They can live on land and in water. 2.They have moist skin. 3.Scales are absent. 4. Two pairs of pentadactly limbs present. 5. Respiration through gills or lungs or moist skin. 6.They lay eggs without coverings. Example: frog ,toad etc.	1.They live on land .Creeping vertebrates 2. Dry skin. 3.They have scales on their skin. 4.Two pairs of pentadactly limbs present but absent in snakes and some lizards. 5. Respiration exclusively by lungs.   6.Eggs have hard coverings. Example: snake, lizards etc.

Q NO 17:-What are the differences between animals belonging to the Aves group and those in the mammalian group?

ANS:-

Aves	Mammalian
1.    Body is covered with feathers. 2.    They are oviparous i.e. lay eggs. 3.     No mammary glands.        4.They possess hollow bones           for flying.	1.    Body is covered with hairs. 2.    They are mostly viviparous i.e. give birth to young ones. 3.    They possess mammary glands for production of milk to nourish their young ones. 4.    No hollow bones.

 

Q NO 18:-What are the advantages of classifying organisms?

ANS:- The advantages of classifying organisms are:

1.  It makes the study of huge varieties of organism easy and organized.

2.  Various organisms can be easily recognized according to their characteristic.

3.  This helps us to understand the relationship of various organisms among different groups.

 

Q NO 19:- How would you choose between two characteristic to be used for developing a hierarchy in classification?

ANS:-: Every organism has numerous characteristic on the basis of which it can be distinguished from another. The characteristic dependent on the previous one decides the variety in the next level. So, interdependence of two characteristics (like habitat, cellular structure, mode of nutrition or reproduction etc.) may be used for developing a hierarchy in classification.

 

Q NO 20:- Explain the basis for grouping organisms into five kingdoms.

ANS:- The basis of grouping organisms into five kingdoms are :

1. Prokaryotic or Eukaryotic cell.

2. Unicellular or multicellular organisms.

3. Cell structure, like whether the cell has a cell wall or not.

4.Mode of nutrition, whether they are autotrophs or heterotrophs.

 

Q NO 21: What are the major divisions in the Plantae? What is the basis for these divisions?

Ans:The major divisions in the Kingdom plantae are:

a.Thallophyta

b.Broyphyta

c.Pteriodophyta

d.Gymnosperms

e.Angiosperms

The bases for these divisions are:

1. Whether plants body is differentiated into distinct components or not.

2.  Whether plants have vascular tissue for transportation of water and other substances or not.

3.Whether seeds are enclosed in fruits or not.

 

Q NO 22:- How are the criteria for deciding division in plants different from the criteria for deciding the subgroups among animals?

ANS:-(The criteria for deciding divisions in plants are given in above answer).The basic body design of plants and animals are not the same, so instead of considering vascular tissues, seeds, fruits etc. Other features like presence or absence of vertebral column, respiratory organs etc are considered for deciding the subgroups among animals.

 

Q NO 23:-Explain how animals in vertebrate are classified into further sub-groups.

ANS:-The animals in vertebrata are classified into further subgroups on the basis of following characteristics.

Pisces:

a. Scales on the skin.

b. Breathing through gills

c. Aquatic.

d. Lay eggs in water

2. Amphibia:

a.Slimand smooth skin.

b.Gills in larvae but adults breathe through lungs.

c.Can live on land and in water.

d. Lay eggs in water.

3. Reptilia:

a. Body covered with scales.

b. Breathing through lungs.

c. Creeping animals.

d. Lay eggs outside water.

 

 

4. Aves:

a. Body covered with feathers.

b. Hollow bones.

c. Forelimbs modified into wings.

d. All birds .

 e.Lay eggs outside water.

5.Mammalian:

a. Hair on skin.

b. External ear.

c. Give birth to young ones and suckle them.

d.Mammary glands present.