English 10th
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MATH-10TH
SCIENCE
PHYSICS: UNIT I : Light-Reflection and Refraction
UNIT II : The Human Eye and the Colourful World
UNIT III : Electricity
UNIT IV : Magnetic Effects of Current
UNIT V : Sources of Energy
CHEMISTRY :
UNIT VI : Chemical Reactions and Equations
UNIT VII : Periodic Classification of Elements
UNIT VIII : Carbon and its Compounds
UNIT IX : Metals and Non-metals
UNIT X : Acids, Bases and Salts
LIFE SCIENCE :
UNIT XI : Life Processes
LIFE PROCESSES:-
The basic functions or activities performed by
living organisms to maintain their life on earth are called life processes.
Physiology is the branch of science which deals with the study of life
processes and the functions .of different organs and tissues. The basic life
processes are nutrition, respiration, transportation, excretion, movement, reproduction,
growth and control & co-ordination.
NUTRITION
Food is an
organic substance. Glucose is the simplest form of food. Nutrient is a
substance which an organism uses as energy source e.g carbohydrates, fats,
proteins, mineral salts, vitamins are nutrients. carbohydrates and fats are
known as energy foods because they only provide energy, proteins and mineral
salts are known as Body building foods
because they are used to built up body mussels where as vitamins are known as
regulating food. Nutrition is a process of intake of nutrients like
carbohydrates, fats, vitamins, minerals and fluids and its digestion,
absorption and assimilation by an organisms as well as the utilization of these
nutrients for energy purpose by the organism.
HOW DO LIVING THINGS GET THEIR FOOD/
METHODS OF NUTRITION/ MODES OF NUTRITION:- Modes of nutrition means methods of
obtaining food by an organism. They are mainly classified into two main types and
are:-
(a)
Autotrophic
nutrition
(b) Heterotrophic
nutrition
(a) Autotrophic
nutrition:-(Auto = self & trophic = nutrition).So autotrophic nutrition
means self nourishing or it is that mode of nutrition in which an organism
makes or synthesizes its own food from the simple inorganic materials like CO2
and H2O with the help
of sunlight energy & Chlorophyll. e.g all the green plants, Algae and
bacteria etc. .
Autotrophic nutrition is divided
into two categories on the basis of the way of
manufacturing of food.
(i)Photosynthesis.
(ii)Chemosynthesis.
(i)Photosynthesis:-The process by which green plants and some other
organisms use chlorophyll, CO2 and H2O to synthesize food
in presence of Sunlight is known as photosynthesis. Photosynthesis in plants
generally involves the green pigment chlorophyll
and generates oxygen as a by-product. The organisms which shows photosynthesis
are referred as photo-autographs and
this process is also known as photo-autotrophic nutrition e.g All green plants
show this type of nutrition.
(DIAGRAM
SHOWING PHOTOSYNTHESIS IN PLANTS)
(ii)Chemosynthesis:-in this process certain organisms mostly specialized
bacteria extract energy (inorganic compound) like carbon, hydrogen
sulphide,Iron, hydrogen, Ammonia and carbon-dioxide from the environment and
convert that energy into food (organic compound) in absence of sunlight. Organisms
which shows this type of nutrition are referred as Chemo-autotrophs and this
process is also called as chemo-autotrophic nutrition. These chemo-autotrophs
are generally microscopic organisms and are commonly found where iron, sulphur and magnesium is present
generally in soil, rivers and ground water sources. E.g Sulphur Bacteria (Thiobacillus
Thiooxioxidans), hydrogen bacteria, Iron bacteria (ferrobacillus)
and nitrifying bacteria (Nitrobacter).
NUTRITION IN
PLANTS:- (PHOTO-AUTOTROPHIC NUTRITION OR PHOTOSYNTHESIS)
Nutrition in plants takes
place by the process of photosynthesis as already discussed above. Oxygen gas
is released during photosynthesis process.
The existence of life on earth depends on photosynthesis. Photosynthesis
is the only process on earth by which solar energy is trapped by autotrophs and
converted into food. In this process energy rich compounds like carbohydrates
are synthesized from simple inorganic compounds like carbon-dioxide, water,
chlorophyll in presence of sunlight and
with oxygen being liberated as a by-product. Carbohydrates which are formed
during photosynthesis if they are not used immediately are stored in the form
of Starch in plants.
SITE OF PHOTOSYNTHESIS:- Photosynthesis takes in
green parts of a plant like in leaves, green stems. Upper side of leaf has specialized
cells called as Palisade mesophyll cells, these mesophyll cells contain many
choloroplasts (cell organell), these chloroplasts contain a green pigment
called as chlorophyll. Chloroplast containing cells are present in more
quantity on upper side. Thus, they are able to get more sunlight. Veins in leaf
bring water for photosynthesis.
SOURCES OF RAW MATERIALS FOR PHOTOSYNTHESIS
(conditions necessary for photosynthesis):-
(I)Carbon-Dioxide
(ii)Water
(iii)Chlorophyll
(iv)Sunlight Energy.
(i)Carbon-Dioxide:-
Carbon-dioxide is present in low concentration in atmosphere (0.32%).Carbon-dioxide
enters the leaf through stomata ( a pore
present below side of a leaf flanked by two guard cells).
(ii)Water:- Water is absorbed from the soil through root
hair cells. Water moves by osmosis from root cell to root cell until it reaches
the xylem. It is transported through the xylem vessels up by the stem to the
leaves. In leaves less water is used up for photosynthesis, rest evaporates
from the leaves by the process of Transpiration. This transpiration results in
more water being drawn up from the roots.
(iii)Chlorophyll:- Pigments involved in the
process of photosynthesis are known as photosynthetic pigments. Pigments like
chlorophyll, Carotenoids, Anthrocyanin and Phycobilins may be found in a plant
cell, but in photosynthesis only chlorophyll is used up. Chorophyll is a green
pigment present in chloroplast.The role of chlorophyll in photosynthesis is
vital. Chlorophyll is necessary in order to convert carbon-dioxide and water by
using sunlight, into Glucose and oxygen.
(Internal Structure of a chloroplast)
(iv)Sunlight:- Chlorophyll traps sunlight energy in the form of
Quanta or Photons (packets of energy emitted by light) and convert it into
chemical form of energy i.e ATP (Adenosine tri-phosphate). Sunlight provides energy
required to carry out Photosynthesis. Plants use only 3-6% of total solar
energy.
HOW FOOD IS
SYNTHESIZED DURING PHOTOSYNTHESIS:-
Just like other
organisms, plants also require food which can supply energy for their various
life activities. Green plants manufacture their own food by the process of photosynthesis.
In photosynthesis, energy rich compounds like carbohydrates are synthesized
from simple inorganic compounds like carbon-dioxide, water, in presence of
chlorophyll and sunlight energy accompanied by the liberation of Oxygen gas.
Carbon dioxide is taken from atmosphere by leaves through stomatal pores and
water is absorbed by root hairs which supply this to xylem and finally to leaf
veins. In this process light energy is converted into chemical energy by
cholorophyll which is present in the leaf. The process of photosynthesis takes
place in Choloroplast of mesophyll cells
of green leaves in a plants. The food prepared by the green leaves of a plant
is in the form of simple sugar called glucose, which undergoes the process of
respiration to release energy, which is used in various metabolic activities.
The extra glucose is stored in the form
of starch. The equation for this process can be given as:
(carbon-dioxide) (water) Cholorophyll (glucose)
(Oxygen)
Photosynthesis occur in two phases or steps:
(a)
Light
Phase.
(b)Dark
phase.
(a Light phase/ Light reaction:- This is a type or phase of photosynthesis in which
sunlight energy is used to manufacture food and is also called as light
dependent phase. This reaction takes place inside the thylakoid of
chloroplast.The main purpose of the light reaction is to generate organic
energy molecules such as ATP & NADPH. This reaction happens in various
steps:
(i) Absorption of light energy by
chlorophyll:-This step
takes place in thylakoid region of
chloroplast and involves energy from the sun
is trapped by chlorophyll. Chlorophyll molecule
emits electrons when exposed to sunlight.
(ii)Formation of ATP:- ADP present joins with phosphate group and forms ATP (Adenosene
tri-phosphate).This formation of ATP from
ADP is termed as Photophosphorylation.
(iii)Photolysis of water:-in this step water is splited into Oxygen and
Hydrogen gas by
sunlight energy, this process is called as
photytolysis of water.
(iv)Synthesis of NADPH:- The released hydrogen ion from water is available
to bind with
NADP and reduces it to NADPH.
(b)
Dark phase/ Dark reaction:- This is a type or phase of photosynthesis in which
sunlight energy is not used to manufacture food and is also called as light independent
phase. Instead of sunlight CO2
is used. This reaction takes place in Stroma region of chloroplast. Dark
reaction make use of ATP & NADPH (organic energy molecules) which were
formed in light reaction. This phase or reaction is also called as Calvin
Benison Cycle. ATP provides energy where as NADPH provides electrons to convert
CO2 into carbohydrate (glucose).
SIGNIFICANCE
OF PHOTOSYNTHESIS:-
Photosynthesis is important for a number of reasons:
(a)
Photosynthesis release oxygen into the environment which is utilized by
animals, humans and other microbes for the process of respiration.
(b)Green plants and some other organisms use CO2
& H2O and manufacture
their
own food by the same process. Thus it sustains life on earth.
(c)Fossils fuels like coal and natural gas are
forms of stored solar energy
synthesized
by photosynthesis millions of years ago.
(b) Heterotrophic nutrition:- (Hetero = others
& trophe = nutrition) .So The
heterotrophic nutrition means nutrition or food obtained from others. Heterotrophic
nutrition is that mode of nutrition in which an organism can’t make or
synthesize its own food from simple inorganic materials like Co2 &
H2o but these organisms depend on
other organisms for their food.
All animals have a heterotrophic
mode of nutrition .Most bacteria, Protists, Some non-green plants (parasitic
plant like Cuscuta) and fungi also have heterotrophic mode of nutrition. These
organisms take readymade food from plants and other animals.they are unable to
manufacture their food because they do not have chlorophyll so, cant trap
sunlight energy. Those organisms which
have Heterotrophic mode of nutrition are called heterotrophs.On the basis of nature
of food heteotrophic nutrition is of three types:
Types of Heterotrophic nutrition:
A heterotrophic
organism can obtain its food from other
organisms in three ways and the ways are:
(a) Saprotrophic nutrition.
(b) Parasitic nutrition.
(c) Holozoic nutrition.
(a) Saprotrophic nutrition:- saprotrophic
nutrition is that nutrition in which an
organism obtains its own food from dead & decayed matter, and rotten bread
etc. The organisms which obtains
nutrition by this method are called saprotrophs. Saprotrophs like fungi and Bacteria release
digestive enzymes to breakdown solid organic food into soluble form. These
organisms act as decomposers in an ecosystem. e.g Fungi (yeast, mushrooms), many
bacteria & some flowering plants
like Neottia, Monotropa.
(b) Parasitic nutrition:-The
parasitic nutrition is that nutrition in which an organism derives its food
from the body of another living organism is called parasitic nutrition. The organism which obtains the food is called a parasite
and the organism whose body food is obtained is called the host. Some times a
parasite may damage or kill its host by a phenomenon known as parasitism. e.g
Roundworms, Fungi, Plasmodium, lice and Tapeworms & some non-
chlorophyllous plants some parasites. Some Parasites cause diseases in humans
and are known as pathogenic parasites. Some parasites live out side the host
and derives their food, these parasites are known as ectoparasites. E.g of
ectoparasites are: Bed bug, lice & Ticks & some parasites live inside
host body and these parasites are known as endoparasites. E.g of endoparasites
are: Tenia, plasmodium malarial parasite & E-Coli bacteria.
Some green organisms like E. viridis
& E. gracilis shows autotrophic mode in presence Sunlight energy but shows
saprotrophic mode in absence of Sunlight
energy, This dual mode of nutrition is known as Myxotrophic nutrition.
(c) Holozoic nutrition:-Holozoic nutrition means feeding on solid food. The
holozoic nutrition is that nutrition in which an organism takes the complex
organic food materials into body by the process of ingestion. The ingested food
is digested and then absorbed into body cells of the organism. e.g Human beings
and most of animals have holozoic mode of nutrition.
Depending upon the source of food,
Holozoic or holotrophs are of following types:
(i)Herbivours:-
(Herba= plants & vorare= to eat). Thus, herbivours are those
living things which eat only plants or plant products only.So, they are also called
as plant eaters. E.g:- Sheep, deer, horse & rabbit etc.
(ii)Carnivours:-
(Cornis= meat or flesh & vorare= to eat). Thus, Carnivours are those living
things which eat other animals or animal products only. E.g: Lion, tiger etc.
(iii)Omnivours:-(Omni=
Both way & vorare= to eat). These are those living things which eat both
plants as well as animals or their products.e.g: Human beings, crow etc.
NUTRITION IN LOWER ORGANISMS:-
Digestive system
is different in various organism. In
single celled organisms, the food may be taken in by the entire surface. As the
complexity of the organism increases, different parts became specialized to
perform different functions.
NUTRITION IN AMOEBA AND PARAMECIUM:-
Amoeba is an important protozoa, unicellular animal, Omnivourous and holozoic. found in fresh water. It feeds on microscopic organisms like Bacteria, paramecia, diatoms, dead
matter, plants and animals present in
water. The mode of nutrition in amoeba is Holozoic.
And the process of obtaining food by amoeba is called phagocytosis. Amoeba has no mouth and takes food by using temporary
finger like projection called pseudopodia. The
different processes involved in the nutrition of amoeba are:-
Ingestion
is the process of taking food in the body. Amoeba is a unicellular animal, so it doesn’t have a mouth for
ingestion of food. Amoeba ingests the food by encircling it by forming
pseudopodia. When the food is completely encircled , the food is engulfed in
the form of a bag called food vacuole.
2.Digestion:-
Digestion
is the process of breaking the large and insoluble molecules in small and water
soluble molecules. In amoeba,
several digestive enzymes react on the food present in the food vacuoles and
break it down into simple and soluble molecules.
3. Absorption:-
The food digested
by digestive enzymes is then absorbed in the cytoplasm by the process of
diffusion. While the undigested food remains in the food vacuole. If a large
amount of food is absorbed by amoeba, the excess food is stored in the
cytoplasm in the form of glycogen and lipids.
4. Assimilation:-
During this step
the food absorbed by the cytoplasm is used to obtain energy, growth and repair. This
process of utilizing absorbed food for obtaining energy, repair and growth is
called assimilation.
5. Egestion:-
When a sufficient
amount of undigested food gets collected in the food vacuole, it is thrown out
of the body by rupturing cell membrane. The process of removal of undigested food from the
body is called egestion.
In
Paramecium which is also a unicellular organism .Paramecium cell has definite
shape and food is taken in from specific spot. Food is moved to this spot by
the movement of cilia which cover entire surface of the cell.
NUTRITION IN HUMAN BEINGS:- (Higher Organisms)
The nutrition in higher organisms like human beings, fishes and
other vertebrates takes place through specialized an modified digestive system.
This digestive system is formed of main two parts and are Alimentary canal and
digestive glands. Alimentary canal is further differentiated into many small
organs which perform different functions, so, there is physiological division
of labour. Alimentary canal is also called as digestive tract or Gut, and is
about 9 meters long tube open on both side. The various organs of Human
alimentary canal are:-
Mouth
Buccal cavity
pharynx
Oesophagus (food pipe)
Stomach
small intestines
large intestines &
Anus.
(i)
Mouth:- it is an opening bounded by movable lips and is for
ingestion i.e receiving food.
(ii)
Buccal
cavity:- Buccal cavity is a
complex organ of alimentary canal and is made upof multiple small organs and
they are:-
(a)
Tongue:- Tongue is a thick, muscular and protrusible structure
in the
mouth.
The tongue is covered with moist, pink tissue called mucosa. Tiny
bumps called papillae give the tongue its
rough texture. Thousands of taste
buds cover the surface of the papillae.
(b) Teeth:- The teeth are the hardest
substances in human body. Teeth are present in both the jaws of humans and are
embedded in the sockets of jaw bones. In humans 32 teeth are present and they
are of four types for performing
different functions and are as: Incisors, Canines, premolars (first molars) and
Molars (second molars). This different type of dentation is known as
heterodont.
So, the teeth help
in Mechanical digestion of food i.e they cut , chew and grind the food in
buccal cavity, which increases the surface area of food to mix digestive
enzymes and digest properly.
(iii)Pharynx:- The pharynx is the common channel for deglutition
(swallowing) and respiration.
(iv)Oesophagus:- (Food pipe) The oesophagus is also called as gullet.
It is a long, narrow tube present between mouth and stomach. The muscles of
stomach contracts and expands to allow food into the stomach by a process
called as peristalsis.
(v)Stomach:- It is a thick, muscular and J-shaped digestive organ
that is located in the upper abdomen under ribs. When food enters the stomach,
muscles in the stomach wall create peristalsis that mixes and mashes the food
with gastric juices. It helps in the mechanical churning and chemical digestion
of food.
(vi)Small
intestine:- It is a long
about 5.5 meters long narrow tube present between stomach and large intestine.
it is the place where most of the digestion and absorption takes place. The
small intestines has three regions
(a)Duodenum:- is the
first part of the small intestine & receives bile and juices
from the pancreas, gall bladder and
liver.
(b)Jejunum:- The products of
digestion (sugars, amino acids and fatty acids)
are absorbed here by blood.
(c)Ileum:- the digestive
products which were not absorbed in jejunum are
absorbed
here and Vitamin B12 and bile salts are also absorbed.
(vii)Large
Intestine:- Large intestine
is also called as Large bowel or colon. It is shorter and wider than small
intestine & meant for absorption of water and remaining waste materials is
stored here as feces before being removed by defecation. It is made up of two
parts:
(a)Colon:- is a tubular structure
and is about 1.5 meter.
(b)Rectum:-rectum is a doom shaped
chamber, present at the end of large
intestine. It is meant for storage of
feces for defecation.
(viii)Anus:-
It lies at the base of
gastrointestinal tract and is for egestion.
The glands which are
associated with the human digestive system and form a part of human digestive
system and secrete digestive juices which contain digestive enzymes and they are:-
(i)
Salivary
glands:- In humans there are
3 pairs (Parotid, submandibular &
sublingual
glands) of salivary glands and they secrete saliva which
performs
many functions like lubrication, digestion and immunity. Saliva
also contains
a digestive enzyme called ptyalin or salivary amylase.
(ii)
Gastric
glands:- Gastric glands are
present in the walls of stomach and they secrete gastric juices like HCl and
pepsin which digest proteins into amino acids.
(iii)
Liver:- The largest solid organ in the body, lobulated, vital
and reddish
brown coloured,
situated In the upper part of the abdomen on the right
side. Liver
produces Bile juice (yellowish green coloured) which helps
with
the break down of fat from our food. It also stores glucose in the
form
of glycogen for energy use until needed.
(iv)
Pancreas:- A long, flat and yellow coloured
digestive gland also called as heterocrine gland (dual function: exocrine as
well as endocrine) present just below the stomach. It secretes pancreatic juice
which contains a number of important digestive enzymes, including trypsin, lipase and amylase etc. this juice is
alkaline in nature because of high concentration of bi-carbonate ions(base),
this alkaline nature helps to neutralize the acidic juice from the stomach.
(v)
Intestinal glands:- These digestive glands lie in the walls of small
intestine and secrete intestinal juice also contains enzymes like peptidases, sucrose,
lactase and maltase.
Process Nutrition in human
beings is a vast and long process and takes place in various steps and are:-
Ingestion:-Taking
of food & putting it into the mouth with the help of hand is called
Ingestion.
Digestion:-In
human beings digestion of food starts from mouth. The teeth cut the food into
small pieces, chew and grind it called physical digestion.The salivary glands
in our mouth secrete saliva which contains an enzyme called salivary amylase Or
Ptyalin which digests the starch present in food into sugar called chemical
digestion. Our tongue helps in mixing this saliva with food. The slightly
digested food is swallowed and goes down the food pipe or oesophagus, The walls
of the food pipe start contraction and expansion movements called as
peristaltic movements. Peristaltic movement pushes the food into the stomach. Stomach
walls contain three types of glands in it which secrete gastric juices
(Hydrochloric acid, pepsin enzyme and mucus). The hydrochloric acid creates an
acid medium inside which kills microbes injested with food and facilitates the
action of the pepsin enzyme to digest proteins into amino acids. The mucus
helps to lubricate food so, passage of food becomes easily through intestines
and to protest stomach wall from hydrochloric acid effect. The partially
digested food then goes into Duodenum , this duodenum part receives secretions
of two glands (liver and pancreas) through a common duct or pipe called as hepato
pancreatic duct. This hepato pancreatic duct contains both secretions of liver
as well as pancreas. Liver secretions contain bile which makes the acidic food
coming from the stomach alkaline so that pancreatic enzymes can act on it &
break the fats present in the food into into fat globules. While as the
pancreatic secretion contains pancreatic juice which contains enzymes which help in digesting undigested proteins
and fats. The walls of the small intestines contain glands which secrete
intestinal juice which contains enzymes present in it finally convert the
proteins into amino acids, starch into sugar and fats into fatty acids and
glycerol. i.e converts large molecules into water soluble molecules & Hence
digestion of food is completed.
Absorption:- The small intestines is the main region for the absorption of digested
food. The inner surface of the small intestines has numerous finger like
projections called Villi which increase the surface area of for rapid
absorption of digested food. The molecules
of the digested food are so small that they can pass through the walls of the
small intestine which contain blood vessels. This digested food is now absorbed
by walls of small intestines and goes into our blood. This process is called
absorption.
Assimilation:-The process of carrying of absorbed food molecules by blood to all the
cells of our body where it becomes assimilated and is utilized for obtaining
energy. The process is known as assimilation.
Egestion:-
Also known as defaecation.The undigested
or unabsorbed food remained is sent to
large intestines where more villi absorb water from this material and remained
is passed out in the form of feces through Anus, The exit of feces is regulated
by an anal sphincter. The process is known as egestion.
(DIGESTIVE
SYSTEM OF HUMAN BEING)
DENTAL CARIES:-
This is also known as tooth decay. Teeth are the hardest material of human body
composed of calcium phosphate. Enamel is the outermost covering of a tooth,
below enamel is present another layer known as dentine and is similar to a
bone. This dentine covering surrounds the pulp cavity which contains blood
capillaries, nerves etc.
Dental caries is one among the most
common diseases of teeth, mainly it occurs to premolars and molars due to
larger surface area. Generally it is common in those persons whose diets are
rich in carbohydrates which needs less chewing and stick to the teeth. Dental
caries is caused by acidogenic bacteria (acid producing) like streptococcus mutans, in presence of
high sugar concentration. Symptoms of this disease is characterized by
softening of enamel and dentine coverings due to decalcification. Many Bacteria
and food particles stick to teeth and form dental plaques to cover the teeth.
Saliva cant neutralize the acid( formed by bacteria). Finally it leads to existence of cavities in the teeth and
inflammation of pulp with swear pain called as pulpitis. Preventive measures
can be to avoid sugar rich eatables, regular brushing of teeth after meals
& vigorous chewing of fibrous foods.
RESPIRATION
Respiration:-The process of respiration involves taking of Oxygen through nose to
lungs and then sent it into the cells ,using it for releasing energy from food
and elimination of Carbon-dioxide and water from the body is known as
Respiration. Respiration process can be represented as:
(oxygen) (Carbon-dioxide) (water)
The process of respiration takes place inside the cells of the
living body. So, it is also known as the cellular respiration. Respiration is
essential for life because it provides energy for carrying out all the life
processes which are necessary to keep the organisms alive. We can
study cellular respiration by taking the example of the complete oxidation of
glucose. This molecule is oxidized and broken down gradually in two distinct
stages. The first stage is called glycolysis, which involves anaerobic
respiration.
This takes place in the cytoplasm of the cell. The second stage
involves aerobic respiration, which takes place inside the mitochondria of the
cell.
Process of respiration can be devided
into two categories and they are:-
Types of Respiration:-There are two types of respiration and are:-
(a).Aerobic
Respiration.
(b).Anaerobic Respiration.
(a).Aerobic respiration: It is that mode of respiration in which an organism uses
oxygen for Respiration is called aerobic
respiration.In aerobic respiration the glucose food in the Cytoplasm of the
cell is completely broken down (glycolysis) into two Pyruvate molecules, The
two pyruvate molecules are transported into the Mitochondria of cell where
Oxygen Combines with pyruvate molecules and Combustion reaction takes place.
The products formed at the end of the reaction are Carbon-dioxide, water &
Energy. The number of
molecules of ATP formed in aerobic respiration is 38. Hence the energy made
available is much greater than in the case of anaerobic respiration.
Inside the mitochondria, when an
inorganic phosphate group (PO43-, represented
here as Pi) gets attached to a compound called ADP (adenosine di-phosphate), a
molecule of ATP (adenosine tri-phosphate) is formed.
ADP + Pi →ATP
The energy formed during respiration is stored in the
form of ATP molecules. Aerobic respiration produces high amount of energy for
use by the organisms. Mitochondria are the sites for aerobic respiration in the
cells. E.g:Human beings and plants. The combustion reaction can be represented as follows:
In cytoplasm (2 molecules) ( in mitochondria)
(energy)
(b) Anaerobic respiration:- (Fermentation/Intramolecular)
It is that mode of respiration in which an organism doesn’t uses oxygen for
respiration is called anaerobic respiration. The microscopic organisms like
yeast and some bacteria have anaerobic mode of respiration. In anaerobic
respiration the organism like yeast break down glucose into ethanol (ethyl
alcohol), carbon dioxide and energy.
Anaerobic
respiration produces much less energy which gets stored in ATP molecules. In
anaerobic respiration glucose gets converted into two molecules of private,
which contains three carbon atoms. These reactions also produce two molecules
of ATP.
The oxidation of glucose in a series of reactions leading to the
formation of private is called glycolysis. Glycolysis means ‘splitting of sugar’. It takes place in all
organisms, in the cytoplasm of the cell. It is the first stage of respiration (both
aerobic and anaerobic). After glycolysis, its product (private) gets converted
into different compounds depending on whether further reactions take place in
the presence or absence of oxygen. Glycolysis is the last energy-producing
stage in case oxygen is absent or in low supply, and in cells that lack
mitochondria. After glycolysis, further anaerobic reactions produce different
products like lactic acid or ethanol (ethyl alcohol) in different situations.
This step completes the anaerobic respiration of glucose. Anaerobic respiration
resulting in the formation of these products is also called fermentation.
Examples
of lactic acid fermentation and alcohol fermentation are given below:
In a low supply of oxygen, yeast converts pyruvate to ethanol and
carbon dioxide. Certain bacteria (which lack mitochondria) convert pyruvate to
lactic acid. When our muscles are overworked, blood is unable to supply oxygen
fast enough for producing energy through aerobic means. In this low-oxygen
condition pyruvate gets converted to lactic acid. Accumulation of excess lactic
acid in the muscles causes pain.
This can be represented as:-
in cytoplasm (2 molecules) in Yeast
(Ethanol) (Energy)
Some
times Anaerobic respiration takes place in Bacteria and in our muscles during
heavy physical exercise and can be represented as follows.
in cytoplasm (2 molecules) in muscle cell
Difference between Aerobic and Anaerobic respiration
1)
Aerobic
respiration takes place in presence of 1)
Anaerobic respiration takes place in absence
Oxygen. Of Oxygen.
2)
Complete breakdown of food occurs in
aerobic 2) Partial break down of food occurs in
anaerobic
respiration.
respiration.
3)
End
products of aerobic respiration are CO2, 3) End products of anaerobic respiration are
H2O
& Energy. CO2 , Ethanol & Energy.
4)
Aerobic
respiration produces a high amount of 4) Anaerobic
respiration produces much less
Energy.
Energy.
RESPIRATION IN PLANTS:- Plants
like other animals also respire. Plants also need energy. The plants get energy
through the process of respiration in which glucose food breaks down in the
presence of oxygen to form carbon dioxide and water with the release of energy.
This energy is used by the plant for carrying out its various life processes.
Thus, Like other organisms, plants also respire for their survival. The
respiration in plants differs from that of animals. In other words, in plants,
each part can independently take in oxygen from air, utilize it to obtain
energy, and give out carbon dioxide.
Respiration In Leaves:-
The leaves of plants have tiny pores
on their surface which are called stomata. The exchange of gases in the leaves
during respiration takes place through stomata.This happens as follows: Oxygen from
the air enters into a leaf through stomata and reaches all the cells by the
process of diffusion. This oxygen is used in respiration in cells of the leaf.
The carbon dioxide produced during diffuses out from the leaf into the air
through same stomata.
The photosynthesis reaction makes
glucose and the respiration reaction break it down. In photosynthesis, the
energy which goes into the reaction is light energy. In respiration, the energy
which comes out is chemical energy.
Respiration in Roots:-
The
roots of plants are under the ground but root cells also need oxygen to carry
out respiration and release energy for their own use. The roots of a
plant take up air from the spaces between the soil particles. Root hairs
are in contact with the air in the soil particles. Oxygen from the air in soil
particles diffuse into root hair and reach all the cells of the root where it
is utilised in respiration. Carbon dioxide produced in the cells of the root
during respiration goes out through the same root hair by the process of
diffusion.
If a potted plant is over watered for
a long time, then the plant may ultimately die. This is because too much water
expels all the air from in between the soil particles. Due to this, oxygen is
not available to the roots for aerobic respiration. In this condition, the
roots of plant respire anaerobically producing alcohol. This may kill the
plant. Germinating seeds during early stage respire anaerobically because they
have seed coat which does not allow the oxygen to enter through it.
Respiration in plants happens throughout the
day and night thereby carbon dioxide is produced. However, during the daytime,
the amount of carbon dioxide released is negligible compared to the amount of
oxygen produced as a result of photosynthesis. Hence, one should not sleep
under a tree at night.
Inhalation:-Intake of O2 into the body is called Inhalation. Exhalation:-Out put of CO2 from the body is called Exhalation. Breathing:- Intake of oxygen and output of carbon-dioxide is
called breathing.
Respiration
in Animals
Different
animals have different types of respiratory organs which uptakes oxygen and
removes carbon dioxide out of body. For example, in unicellular organisms such
as amoeba and paramecium exchange of gases
takes place through plasma membrane by
simple diffusion. In earthworm, leech
and frogs exchange of gases takes place through their moist skin. In insects such as grasshopper and cockroach respiration
is done through spiracles and
trachea. In aquatic animals such as fish respiration takes place through special respiratory
organs called gills. While in all the land animals such as birds, dog, cat, cow and humans respiration
takes place through special respiratory organs called lungs. Now, we shall discuss
respiration in amoeba, insects, earthworm, fish and human beings in
detail.
Respiration
in Lower organisms (Amoeba & Paramecium):-
We know that amoeba is a unicellular
organism which lives in fresh water. This organism does not have a specialized
organ to do the process of respiration. So in amoeba respiration takes place
through its cell membrane also called plasma membrane. Amoeba gets oxygen gas dissolved in surrounding
water through its plasma membrane by the process of diffusion. The oxygen gas diffused
inside the body is used up by amoeba. In the body the oxygen gas absorbed is
used to break down the complex food material into simple molecules. During
these metabolic reactions in the body of amoeba the oxygen gas is converted into
carbon dioxide gas. The carbon dioxide gas is also liberated in the surrounding
water through the same process of diffusion.
SKIN
RESPIRATION:- Skin respiration is also known as Cutaneous respiration, or cutaneous gas exchange, is a form of respiration in which gas exchange occurs across the skin or outer integument of an organism rather
than gills or lungs. Cutaneous respiration may
be the sole method of gas exchange, or may accompany other forms, such as ventilation. Cutaneous respiration occurs in a wide variety of
organisms, including insects, amphibians, fish, sea snakes, turtles, and to a lesser
extent in mammals, including humans.
RESPIRATION IN FISHES:- Gills
mediate the gas exchange in fish. These organs, located on the
sides of the head, are made up of gill filaments, feathery structures that
provide a large surface for gas exchange. The filaments are arranged in rows in
the gill arches, and each filament has lamellae, discs that contain
capillaries. Blood enters and leaves the gills through these small blood
vessels. Although gills are restricted to a small section of the body, the
immense respiratory surface created by the gill filaments provides the whole animal with an efficient gas exchange.
The surrounding water keeps the gills wet.
A flap, the operculum, covers and
protects the gills of bony fish. Water containing dissolved oxygen enters the fish's
mouth, and the animal moves its jaws and operculum in such a way as to pump the
incoming water through the gills. As water passes over the gill filaments,
blood inside the capillaries picks up the dissolved oxygen. Since the blood in
the capillaries flows in a direction opposite to the flow of water around the
gill filaments, there is a good opportunity for absorption. The circulatory
system then transports the oxygen to all body tissues and picks up carbon
dioxide, which is removed from the body through the gills. After the water
flows the gills, it exits the body behind the fish's operculum.
RESPIRATION IN HUMAN BEINGS:- (LUNG RESPIRATION/ PULMONARY RESPIRATION)
The respiratory system (also respiratory apparatus, ventilatory system, gas exchange system) is a biological system consisting of specific organs and structures used for gas exchange or rid of carbon dioxide and taking in oxygen. Carbon dioxide, a waste product, goes
out of the body. Oxygen, which the body needs, comes in. The lungs are the main organ to do
this. The main
organs of this respiratory system are:-
Nose
Nasal passage
Pharynx
Trachea (Wind pipe)
Bronchi
Lungs &
Diaphragm
The first step in respiration is
breathing of oxygen, or inhaling. The second step is gas exchange
in the lungs where oxygen is diffused into the blood and the carbon dioxide diffuses out of the
blood. The third process is cellular respiration, which produces the chemical energy that the cells in the body need, and carbon dioxide.
Finally, the carbon dioxide from cellular respiration is breathed out of body from the lungs.
The human respiratory system begins from the nose there
is a passage behind the nostrils which
is called nasal passage. The O2 for respiration is drawn into our
body through the nasal passage the dust particles present In Oxygen are trapped
by nasal hairs to clean air that goes into the lungs. The part of the throat
between the mouth and the windpipe is called as pharynx. From nasal passage air
enters into pharynx which then goes into the windpipe or trachea. The trachea
runs down the neck and divides into two smaller tubes called bronchi at its
lower end. The two bronchi are connected with two lungs. The lungs are separated
from abdominal cavity by a muscular layer called diaphragm. Each bronchi
divides in the lungs to form a large number of smaller tubes called
bronchioles. At the end of these bronchioles tiny air sacs or grape wine like
structures are present called alveoli. The walls of alveoli are surrounded by
blood capillaries. It is the alveoli where gaseous exchange takes place. During
breathing the lungs expand, decreasing the air pressure in the lungs. This is
caused by the diaphragm (a sheet of muscular tissue that
separates the lungs from the abdomen) and the muscles between the ribs contracting to expand the chest,
which also expands the lungs. As the air pressure inside the lungs are lower
when it has expanded, air from outside at higher pressure comes rushing into
the area of low pressure in the lungs.
The
lungs are made of many tubes or branches. As air enters the lungs, it first
goes through branches called the bronchi, then through smaller branches
called bronchioles, and finally into the air sacs. Gas exchange occurs in the air
sacs where oxygen is exchanged with carbon dioxide. The carbon dioxide in the
air sacs now need to be exhaled, or breathed out. In the reverse process to
inhaling, the diaphragm and the rib muscles relax, causing the lungs to be
smaller. As the air pressure in the lungs is greater when the lungs are
smaller, air is forced out. The exhaled air has a high concentration of carbon
dioxide and a low concentration of oxygen. The maximum volume of air that can
be breathed in and breathed out is called the vital capacity of the lungs and
is up to five liters.
The inhaled air goes down to the air sacs at the end of
each bronchiole. The air sacs are called alveoli, they have a large surface area,
and are moist, thin, and close to a blood supply. The inhaled air has a much
greater concentration of oxygen than carbon dioxide whilst the blood flowing to
the lungs has a more carbon dioxide than oxygen. This creates a concentration gradient between the air in the air sacs and the blood,
meaning there is more oxygen in the air than the blood.
As the alveolar membrane, oxygen can easily diffuse in and out. Oxygen at high concentration in the alveoli diffuses into the haemoglobin of blood (where oxygen concentration is low) and forms oxy-haemoglobin, and carbon dioxide at high concentration in the blood diffuses into the air sacs where carbon dioxide concentration is low(So, haemoglobin is called respiratory pigment). It is the alveoli where gaseous exchange takes place. As the blood passes through the tissues of the body, the O2 present in it diffuses into the cells. The oxygen in the blood is passed to all the cells and is used by the cells in the body. The O2 combines with the digested food present in the cells and releases energy from it. CO2 gas is produced as a waste product during respiration in the cells. The carbon dioxide is finally sent back from cells to alveoli through same path and is exhaled out from the body.
The breathing
rate in an adult man at rest is about 15-18 times per minute.
(RESPIRATORY SYSTEM OF HUMAN BEING)
(structure of alveoli)
TRANSPORTATION Transportation:- In Biology, transportation is a life
process in which a substance absorbed in one part of the body of an organism is
carried to other parts of its body. Large organisms need transport systems in
their bodies to supply all their cells with food, O2, H2O,
& other materials. Special tissues and organs are need for the transport of
substances in plants and animals.
Transportation in Plants:-
Transport system in
plants is less elaborate than in animals. Plants are less active, so their cells
don’t need to be supplied with materials so quickly. All the cells of a plant
can get O2 for respiration & CO2 for photo synthesis
from atmosphere directly. So the only substances which are to be supplied to a
plant through a transport are water & minerals. Another job of the
transport system of plant is to transport food prepared in the leaves to the
various parts of the plant. In case of plants, the
biggest concern is the transport of water and it terminates at the limiting
factor depending on its growth. To overcome this problem, a tree uses several
processes like Translocation, Storing, Absorption and Utilization of
water. The plant
have two types of conducting tissues for transportation and are Xylem &
phloem:
(a). Xylem OR Wood:- which carries
H2O & minerals from roots towards leaves. The xylem vessel is a long non
living tube which runs like a drain pipe through the plant. A xylem vessel is
made of many hallow dead cells called xylem elements joined end to end, so an
open tube is formed. Xylem vessel runs from the roots of the plant right up to
the leaves. It transports water & other minerals from roots towards leaves.
The continuous evaporation of H2O or transpiration from the cells of a leaf
creates a kind of suction which pulls up water through the xylem.
Structure:- Xylem is the most distinctive complex tissue formed of
four different types of cells : Tracheids, Vessels, xylem parenchyma and fibers cells. Among these cells most abundant are vessels and are long sized. Vessel elements are connected together into
long tubes. Tracheids
are long thin spindle shaped cells with pits in their thick cell walls. H2O
flows from one tracheid to another through pits. Tracheids are the dead cells
and don’t open their ends so they don’t form vessel.
Function of Xylem:-The
main function of xylem is to transport water, and some soluble nutrients
including minerals and inorganic ions, upwards from the roots to the rest of the
plant. Xylem cells form long tubes that transport materials, and the mixture of
water and nutrients that flows through the xylem cells is called xylem sap.
These substances are transported through passive transport, so the process doesn’t require
energy. The phenomenon that allows xylem sap to flow upwards against gravity is
called capillary action. This occurs when surface tension makes liquid move
upward. Water is also aided in moving up through the xylem by adhering to the
xylem cells. However, it gets harder to work against gravity to transport
materials as a plant grows taller, so xylem sets an upper limit on the growth
of tall trees. In order to make food through photosynthesis, plants need to absorb carbon dioxide from the atmosphere and water from
the soil. However, when the stomata small holes in a plant’s leaves are open to
allow CO2 in, a lot of water evaporates, much more than the amount
of CO2 taken in. Plants that developed systems to transport water to
the sites of photosynthesis on leaves had a better chance of survival.
(b). Phloem:- which carries food from leaves to other parts of a plant .
Like xylem , phloem is made of many cells joined end to end to form long tube.
The cells in phloem which are joined end to end are called sieve tubes. Sieve
tubes which form phloem are living cells which contain cytoplasm but no
nucleus. Each sieve tube cell has a companion called next to it companion cell
has a nucleus and many other cell organelles.
Structure:- Phloem is composed of several cell types
including sclerenchyma, parenchyma,
sieve elements and companion cells. These sieve plates are areas with many
pores through which adjacent cells are connected by a continuous cytoplasm.
Function:- Phloem is the vascular tissue responsible for the transport of food nutrients such as glucose, amino acids, proteins and mRNAs from source tissues (ex-photosynthetic
leaf cells) to sink tissues (ex. Non-photosynthetic root cells or developing
flowers). i.e from leaves to all other cells of the plant by the
process called translocation. Phloem shows bi-directional movement of food
particles.
Transportation of water and other minerals in plants:-
Plants require H2O for making food by
photosynthesis process. Plants also need minerals salts for various purposes. H2O
& minerals are absorbed from the soil by the roots of the plant &
transported to the various parts of the plant like stem, leaves & flowers.
H2O & minerals move from roots of the plant to its leaves
through two kinds of elements of the xylem tissues called as xylem vessels
& tracheids. This transportation process takes place by transpiration pull
theory, which states that: Water is pulled from above and not pushed from below
through roots, As there is gravitational force downside but still two forces
are there which helps to pull the water upward I.e. Cohesive and adhesive
forces.
In
cohesive force water molecules cling together to form a chain in plants. Where
as in Adhesive force helps in attachment of these water chains to various parts
and walls of the xylem. In a simple words, when we water a plant so it takes
that Water with the help of roots and this water should be transported to the
upper parts, for this purpose the water is translocated in xylem through
suction force. This suction is actually pulling water upward so called
transpiration pull.
TRANSPIRATION:- Transpiration is the process of water loss
from leaves of plants through stomata. Transpiration mostly occurs in leaves
through special structures present on them called as stomata. Transpiration
always occurs against the gravity. Transpiration involves mainly the xylem
cells which become active during absorption process by the roots. Opening of
stomata is controlled by K+ ion.
Types of
Transpiration:-
(a) Stomatal
Transpiration:-
Stomatal transpiration is the
evaporation of water from a plant’s stomata. Most of the water that is
transpired from a plant is transpired this way; at least 90% of the water transpired from a plant’s
leaves exits through the stomata. Near the surface of the leaf, water in liquid
form changes to water vapor and evaporates from the plant through open stomata.
(b) Cuticular Transpiration:-
Cuticular transpiration is the
evaporation of water from a plant’s cuticle. The cuticle is a waxy film that
covers the surface of a plant’s leaves. This form of transpiration does not account for much of a
plant’s water loss; about 5-10 percent of the leaves’ water is lost through the
cuticle. When plants close their stomata in dry conditions, more water is
transpired this way.
(c)
Lenticular transpiration:-
Is the type of transpiration which
occurs through the small pores called as lenticels present in the bark. It
constitutes about 15%-20% of total transpiration. It occurs throughout the day
and night. These are dead and are exterior to bark. As the layer above the bark
is dead, these lenticels help in the exchange of gases through dead
areas.
Transport of food & other substances in Plants:-
Leaves
make food by the process of photosynthesis. Every part of the plant needs food
for their growth. So, the food manufactured in the leaves is transported to all
the other parts through phloem. The transport of food from the leaves to other
parts of the plant is called translocation. Food is
transported by a special mechanism caleld as pressure flow hypothesis. Pressure
flow hypothesis is the one which explain the translocation of food molecules by
phloem. The mechanism of translocation involves certain steps.
As sugar is synthesised in the
leaves by the process of photosynthesis, a high concentration of organic
substance inside the phloem cells of the leaf creates a diffusion gradient by
which more water is sucked into the cells.
Phloem sap with lot of sugar
moves from sugar sources (leaves) to sugar sinks with the help of turgor
pressure.Sugar sources are the organs of the plant which synthesise sugars.
Sugar sinks are the ones from where the sucrose is removed from the phloem.
Hydrostatic pressure increases in the phloem
sieve tubes, pressure flow begin sand the sap moves through the phloem.
Osmotic pressure at the sink is
reduced. Sucrose from the phloem sap is removed and given to the cells which
utilize it by converting it into energy or starch or cellulose.
Transportation in Animals:- in all leaving beings the
nutrients and gases are transported to and from all parts of the body. This is
essential to carry on various life processes. In case of unicellular and small
multicellular organisms transport takes place by diffusion. However, in large
multicellular organisms, as the distances between different body parts have
increased, they need an elaborate and efficient system for transportation of
materials. In large animals, such a system is called circulatory system in which a fluid circulates in all parts of
the body. Annelids are the first metazoans to have a well developed circulatory
system. In many invertebrates this fluid is the haemolymph, where
as in all vertebrates and in some higher invertebrates this fluid is the blood.
Transport
in Humans:- The
main transport system in human beings is the blood circulatory system, blood
carries O2, digested food & other chemicals like harmones &
enzymes to all the parts of the body. It also takes away the waste products
like CO2 & urea produced in the body cells. In human beings, the
various organs associated with this system include the heart, lungs, blood
vessels, capillaries, and blood. The heart is the pumping organ that
squirts out blood. The heart does this with so much pressure that it is capable
of squirting blood up to 9 meters high. It never stops and beats continuously
so that blood can travel to all parts of the body. our blood travels through
these blood vessels transporting oxygen, carbon dioxide, digested food,
hormones and even waste products. It is amazing to see how transportation in
human beings is carried out by the circulatory system, with the heart and the
vast network of blood vessels. The main organs of human circulatory system
consists of the heart & blood vessels (Artries,veins & capllaries) & Blood.
Human circulatory system:-
The various organs of
the circulatory system are:
Heart
Arteries
Veins
Capillaries &
Blood.
Human Heart:- It is a clenched fist sized,
thick, muscular and contractile organ.It is surrounded by a thin, transparent
layer called Pericardium. This pericardium protects heart from mechanical
shock.In circulatory system the heart acts as a pump to push out blood. The
arteries, veins & capillaries acts as pipes or tubes through which the
blood flows.
The heart is roughly triangular in
shape. It is made of special muscle
called cardiac muscle. The size of the heart is about the same as our clenched
fist. The heart has four chambers inside it . The upper right chamber of the heart is called right atrium
& left one is called left atrium & the lower right chamber is called
right ventricle & the left one is called left ventricle. Right and left
auricles are separated by a thin layer called interauricular septum. The right atrium
or auricle receives deoxygenated blood (rich in carbon dioxide) from most of
the body parts by superior vena cava or main vein, while as left auricle
receives oxygenated blood (rich in oxygen) from the lungs by pulmonary vein.
interauricular septum prevents the mixing of two types of blood. And the two
ventricles transport blood to the entire body. Ventricles are larger and thick
walled than auricles because these have to pump blood to various organs of the
body. Right an d left ventricles are separated from each other by a thick
muscular layer called as interventricular septum which also prevents mixing of
two types of blood. Both auricles are connected with ventricles by
atrioventricular valves. The right atrium gives deoxygenated blood to right
ventricle through a valve called tricuspid valve or V2. Similarly the left
atrium gives oxygenated blood to left ventricle through a valve called as
bicuspid valve or V1. These valves prevent the back flow of blood into atria
when these ventricles contract. When right ventricle contracts de-oxygenated
blood from it passes to lungs by pulmonary aorta or pulmonary vein & is guarded
by seminal valves, while as contraction of left ventricle passes the oxygenated
blood to all the parts of body through
systemic aorta or main artery & is guarded by seminal valve also. The job
of the heart is to pump the blood to the whole body. Ventricles pump the blood
to rest of the body with high pressure so ventricles are made up of thicker
wall than atria. The chambers of the heart are separated by a partition called
septum.
Arteries:- Arteries are the thick walled blood vessels which carry blood
from the heart to all the parts of the body. Arteries carries Oxygenated blood.
Capillaries:- The capillaries are
thin walled & extremely narrow tubes of blood vessels which connect
arteries with veins.
The
exchange of various materials like O2, food, CO2 etc
between the blood & the body cells takes place through capillaries.
Veins:- Veins are thin walled blood vessels which carry blood from
all the parts of body back to the heart. Vein carries De-oxygenated blood.
The main difference
between the artery & the vein is that an artery carries blood from the
heart to the body organs where as a vein carries blood from the body organs
back to the heart.
The blood carrying O2 in it is
called oxygenated blood. The blood having no O2 in it is called deoxygenated
blood.
(Diagram
to show the inside structure of human heart)
How heart works/ Blood flow:-
All blood enters the right side of the
heart through two veins: The superior
vena cava (SVC) and the inferior vena cava (IVC).
The SVC collects blood from the upper half of the body.
The IVC collects blood from the lower half of the body. Blood leaves the SVC
and the IVC and enters the right atrium (RA). When the RA contracts, the blood
goes through the tricuspid valve. and into the right ventricle (RV).
When the RV contracts, blood is pumped through the pulmonary valve, into the pulmonary artery (PA) and into the lungs where it picks up oxygen. Because
blood returning from the body is relatively poor in oxygen. It needs to be full
of oxygen before being returned to the body. So the right side of the heart
pumps blood to the lungs first to pick up oxygen before going to the left side
of the heart where it is returned to the body full of oxygen.
Blood
now returns to the heart from the lungs by way of the pulmonary veins and goes into the left atrium(LA). When the LA contracts, blood travels through the mitral valve and into the left ventricle (LV). The LV is a very important
chamber that pumps blood through the aortic valve and into the aorta. The aorta is the main artery of the body. It receives all
the blood that the heart has pumped out and distributes it to the rest of the
body. The LV has a thicker muscle than any other heart chamber because it must
pump blood to the rest of the body against much higher pressure in the general
circulation (blood pressure).
Double circulation:
A circulatory system
in which the blood travels twice through the heart in one complete circulatory
cycle is called double circulation.
In human beings heart is four
chambered which consists of two Atria and two Ventricles, left side and the
right side of the heart are completely separated to prevent the mixing of
oxygenated blood with deoxygenated blood. Such a separation allows a highly
efficient supply of oxygen to the body cells which is necessary for producing a
lot of energy.
BLOOD:-
Blood is actually a tissue. It is thick because it is
made up of a variety of cells, each having a different job. In fact, blood is
about 80% water and 20% solid. The circulatory system is the route by which the
cells in your body get the oxygen and nutrients they need, but blood is
the actual carrier of the oxygen & nutrients. Blood
is made mostly of plasma, which is a yellowish liquid that is 90% water.
In addition to the water, plasma contains salts, sugar (glucose), and other
substances. And, most important, plasma contains proteins that carry important
nutrients to the body’s cells and strengthen the body’s immune system so it can
fight off infection. The average man has between 10 and 12 pints of blood in
his body. (one pint of blood is equal to 525 ml) The average woman has between
8 and 9 pints.
Blood
is actually a tissue. It is thick because it is made up of a variety of cells,
each having a different job. In fact, blood is about 80% water and 20% solid. Blood
is made mostly of plasma, but 3 main types of blood cells circulate with the
plasma:
- Platelets help the blood to clot. Clotting
stops the blood from flowing out of the body when a vein or artery is
broken. Platelets are also called thrombocytes.
- Red blood cells carry oxygen. Of the 3 types of blood cells, red blood cells
are the most plentiful. In fact, a healthy adult has about 35 trillion of
them. The body creates these cells at a rate of about 2.4 million a
second, and they each have a life span of about 120 days. Red blood cells
are also called erythrocytes.
- White blood cells ward off infection. These cells, which come in many shapes
and sizes, are vital to the immune system. When the body is fighting off
infection, it makes them in ever-increasing numbers. Still, compared to
the number of red blood cells in the body, the number of white blood cells is low.
Most healthy adults have about 700 times as many red blood cells as white
ones. White blood cells are also called leucocytes.
Blood
also contains hormones, fats, carbohydrates, proteins, and gases.
Maintenance of Platelets:- if injury occurs, naturally the loss of blood from the
system has to be minimized. In addition to avoid this, the blood has platelet
cells which plug these leaks by helping to clot the blood at the time of
injury.
Functions of Blood:- Blood carries oxygen from the lungs and nutrients from
the digestive tract to the body’s cells. It also carries away carbon dioxide
and all of the waste products that the body does not need. (The kidneys filter
and clean the blood). Blood also
- Helps keep
your body at the right temperature
- Carries
hormones to the body’s cells
- Sends
antibodies to fight infection
- Contains
clotting factors to help the blood to clot and the body’s tissues to heal
Types of Blood:-There are 4 different blood
types: A, B, AB, and O. Genes that you inherit from your parents (1 from your
mother and 1 from your father) determine your blood type. Blood is always being
made by the cells inside your bones by a process called haemopoiesis. so, our
body can usually replace any blood lost through small cuts or wounds. But when
a lot of blood is lost through large wounds, it has to be replaced through a
blood transfusion (blood donated by other people). In blood transfusions, the
donor and recipient blood types must be compatible. People with type O blood
are called universal
donors, because they can donate blood to anyone, but they can only
receive a transfusion from other people with type O blood.
Lymphatic System:
There
is another system of tiny tubes called lymph vessels & lymph glands in the
human body which transports the liquid called lymph from the body tissues to
the circulatory system called lymphatic system. Lymphatic system consists of
three parts.
Lymph vessels
Lymph glands &
Lymph.
Lymph:- Lymph
is another medium of circulation in the human body but it flows only in one
direction. Lymph contains two formed elements i.e Plasma and Leucocytes (WBC).
So lymph is blood minus RBC, Platelets and some proteins.
Functions of Lymph:-
1. Lymph acts as a "middle man" which
transports oxygen, food materials, hormones, etc., to the body cells and brings
carbon dioxide and other metabolic wastes, from the body cells to blood and
then finally pours the same into the venous system.
2. Body cells are kept moist by the lymph.
3. Lymph nodes produce lymphocytes. Lymph takes lymphocytes and
antibodies from the lymph nodes to the blood.
4. It destroys the invading microorganisms and foreign particles in the
lymph nodes.
6. It brings plasma protein macromolecules synthesized in the liver
cells and hormones produced in the endocrine glands to the blood. 7.
Lymph maintains the volume of the blood, as soon as the volume of the blood
reduces in the blood vascular system, the lymph rushes from the lymphatic
systems to the blood vascular system.
EXCRETION
Excretion:-
The
process of removal of toxic wastes from the body of an organism is called
excretion. Excretion is a process by which metabolic waste is eliminated from an organism. In vertebrates this is
primarily carried out by the lungs, kidneys and skin. Excretion is an essential process in all forms of life.
For example, in mammals urine is expelled through the urethra, which is part of the excretory system. In unicellular organisms, waste products are discharged directly through the
surface of the cell.
Green plants produce carbon dioxide and water
as respiratory products. Plants can get rid of excess water by transpiration
and guttation. It has been shown that the leaf
acts as an 'excretophore' and, in addition to being a primary organ of
photosynthesis, is also used as a method of excreting toxic wastes via
diffusion. Other waste materials that are exuded by some plants resin, saps, latex, etc. are forced from the interior of the plant by
hydrostatic pressures inside the plant and by absorptive forces of plant cells. Plants also excrete some waste
substances into the soil around them. In animals, the main excretory products
are carbon dioxide, ammonia (in ammoniotelics), urea (in ureotelics), uricacid (in uricotelics), guanine (in Arachnida) and creatine. The liver and kidneys clear many substances from the blood (for example, in renal excretion), and the cleared substances are then excreted from the
body in the urine and feces.
Aquatic animals usually excrete ammonia directly into the external
environment, as this compound has high solubility and there is ample water
available for dilution. In terrestrial animals ammonia-like compounds are converted into other
nitrogenous materials as there is less water in the environment and ammonia
itself is toxic.
Birds excrete their nitrogenous wastes as uric acid in the form of a paste. Although
this process is metabolically more expensive, it allows more efficient water retention and it can be stored more easily in the egg. Many avian species, especially sea birds, can also excrete salt via
specialized nasal salt glands, the saline solution leaving through nostrils in
the beak.
In insects, a system involving Malpighian tubules is utilized to excrete metabolic waste. Metabolic waste diffuses or is
actively transported into the tubule, which transports the wastes to the
intestines. The metabolic waste is then released from the body along with fecal
matter. The excreted material may be also called as ejecta.
The biochemical reactions
taking place in the cells of an organism may produce toxic wastes in the body.
The accumulation of toxic wastes in the body harms an organism. So, far an
organism to lead a normal life, the toxic wastes being produced in its body
must be removed continuously. Excretion takes place in animals as well as in
plants.
Excretion in Human Beings (Urinary
System):-
The
excretory system in human beings consists of following main organs:
(a). Two kidneys.
(b). Two ureters.
(c). Urinary bladder.
(d). Urethra.
(a) Kidneys:- Kidneys are been shaped and are located at the
back of our body just above the waist. Every person has a pair of kidneys. The
blood in our body is constantly passing through our kidneys. The renal artery
brings the dirty blood into the kidneys. The function of the kidneys is to
remove the poisonous substances like urea, other waste salts & excrete them
in the form of a yellow liquid called urine.
Like in lungs each kidneys is made up of a
large number of excretory units called nephrons. The nephron has a cup shaped
bag at its upper end called Bowman’s capsule. The lower end of bowman’s capsule is tube shaped and it is called a
Tubule.The Bowman’s capsule contains a bundle of capallaries which is called
Glomerulus .The function of glomerulus is to filter the blood passing through
it.
(b) Ureters:- The ureter is
a tube that carries urine from the kidney to the urinary bladder. There are two
ureters, one attached to each kidney. The upper half of the ureter is located
in the abdomen and the lower half is located in the pelvic area. The
ureter is about 30 cm long in the average adult. The tube has thick walls
composed of a fibrous, a muscular, and a mucus coat, which are able to
contract.
(c) Urinary bladder:- The urinary bladder is a muscular
sac in the pelvis, just above and behind the pubic bone. When empty, the
bladder is about the size and shape of a pear. Urine is made in the
kidneys and travels down two tubes called ureters to the bladder. The
bladder stores urine. The bladder is lined by smooth involuntary muscles that
stretch to hold urine. The normal capacity of the bladder is 400-600 ml.
(d) Urethra:- is a duct that transmits urine from the bladder to the exterior of the body during urination (urine pass out). The urethra is held closed by the urethral sphincter
(a muscular structure that keep urine in the bladder until voiding can occur). The
female urethra is much shorter than that of the male, being only 4 cm (1.5
inches) long. In the human male, the urethra is about 8 inches (20 cm) long.
The
human excretory system
Structure and function of a Nephron:-
Each
kidney is made up of a large number of excretory units called Nephrons. Histologically, each kidney
is composed of approximately 1 million of Uriniferous tubules or nephron.
Nephron is the structural and functional unit of the kidney. Each nephron has two major portions:
(a) A Renal
corpuscle (Malpighian body)
(b) A Renal tubule
(a)Renal
corpuscles (Malpighian body):- A
renal corpuscle consists of a glomerulus surrounded by a glomerular capsule
(Bowman’s capsule). The glomerulus is
a capillary network that arises from an afferent arteriole and empties into an efferent arteriole. The diameter of
the efferent arteriole is smaller than that of the afferent arteriole, which
helps maintain a fairly high blood pressure in the glomerulus. Bowman’s capsule is double
walled cup like structure and it encloses the glomerulus. The wall of
glomerulus and the Bowman’s capsule consists of a single layer of flattened
epithelial cells. Glomerular capsule consists of three layers:
(i) Outer
parietal layer: consists of squamous epithelium cells
with minute pore of 12nm diameter called fenestration
(ii)
Middle basement membrane which is selectively permeable
(iii) The inner visceral layer of large nucleated
cell called podocytes.
Podocytes bears finger like projections known as podocels. The areas between
the two podocels is filtration slit underlying basement membrane.
(b) Renal tubules:- The renal tubule continues from
Bowman’s capsule and consists of the following parts: proximal convoluted tubule (in
the renal cortex), loop of Henle (in
the renal medulla), and distal
convoluted tubule (in the renalcortex).
(i) Proximal convoluted tubules (PCT): it is proximal
part of renal tubules next to Bowman’s capsule. It is lined with microvilli.
Maximum reabsorption of water, glucose, amino acids and electrolytes takes
place here.
(ii) Loop of Henle: It is U
shaped middle portion of renal tubules. It is composed of ascending and
descending loop. Ascending loop is thick walled and impermeable to water while
descending loop is thin walled and permeable to water. Counter current
mechanism is crucial role of loop of Henle.
(iii) Distal convoluted tubules (DCT): It is the
distal part of renal tubules that leads to collecting ducts. It is similar in
structure and function with PCT.
(iv) Collecting tubules: It
is not a part of nephron rather it is a part of kidney. The distal convoluted tubules
from several nephrons empty into a collecting tubule. Several collecting tubules
then unite to form a papillary duct that empties urine into a minor calyx and then into major calyx and finally
into renal pelvis.
Function:- The function of the nephron is to filter the blood passing
through it. It also takes part in
the reabsorption of useful substances like glucose, amino acids.
TYPES
OF NEPHRON:
1.
Cortical
nephron: 80% of the nephrons are short and located
within the cortex.
2.
Juxta medulary
nephron: 20% of nephron have long loops of Henle that
extend into the medulla.
(STRUCTURE
OF NEPHRON)
Dialysis (Artificial Kidney):-
Dialysis is a treatment method that replicates the
function of the kidneys when they are failing. In healthy individuals, the
kidneys work to filter and remove waste products, excess fluid, salts and
toxins from the blood.
However, in cases of kidney failure, this mechanism fails
and individuals need to undergo dialysis. Dialysis can be used to treat people
with chronic or acute kidney disease. Or The procedure used for cleaning the
blood of a person by separating the waste substances from it is called
dialysis.
Advantages of Dialysys:
·
No set times-
it fits around your life
·
Machine not
necessary- you have supplies that are easily portable
·
Independence
remains
·
Constant
dialysis- so you start to feel better quicker (assuming this method works for
you)
·
Free choice
diet- the joys of being able to eat what you want when you want without any
rigid restrictions as on haemodialysis
·
Less stress
on the circulation. this is a great, simple to use method of dialysis that
allows you to fit dialysis around your lifestyle.
EXCRETION IN PLANTS
Like
animals plants also produce their waste products during their life processes. The
main excretory products like carbon-dioxide and oxygen are removed through
Stomata of leaves. Plants also store some of the waste products in their body
parts like leaves. Plants get rid of these wastes by shedding of leaves, peeling
of bark and felling of fruits etc. Plants also get rid of wastes by secreting
them in the form of gums and resin. Plants also excrete some waste substances
into the around them.
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
TEXTUAL
QUESTIONS
Q NO 1:- Why is diffusion
insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
ANS:-Unlike the unicellular
organisms, the multi-cellular organisms have complex body structures with
specialized cells and tissues to perform various necessary functions of the
body. Since these cells are not in direct contact with surrounding environment
so, simple diffusion cannot meet the oxygen requirement of all these
cells.
Q NO 2:-What criteria do we use
to decide whether something is alive?
ANS:- Any visible movement such as
walking, breathing, or growing is generally used to decide whether something is
alive or not. However, a living organism can also have movements, which are not
visible to the naked eye. Therefore, the presence of life processes is a
fundamental criterion that can be used to decide whether something is alive or
not.
Q NO 3:-What are outside raw
materials used for by an organism?
ANS:- Various outside raw materials
used by an organism are as follows:
→ Food as source of supplying energy and materials.
→ Oxygen for breakdown of food to obtain energy.
→ Water for proper digestion of food and other functions inside the body.
The raw materials required by an organism will vary depending on the complexity
of the organism and its environment.
Q NO 4:- What processes would you
consider essential for maintaining life?
ANS:- Life processes such as
nutrition, respiration, transportation, excretion, etc. are essential for
maintaining life.
Q NO 5:-What are the differences
between autotrophic nutrition and heterotrophic nutrition?
ANS:-
|
Autotrophic
Nutrition |
Heterotrophic
Nutrition |
|
Food is synthesized from simple inorganic
raw materials such as CO2 and water. |
Food is obtained directly or indirectly from
autotrophs. This food is broken down with the help of enzymes. |
|
Chlorophyll is required. |
Chlorophyll is not required. |
|
Food is generally prepared during day time. |
Food can be obtained at all time. |
|
All green plants and some bacteria have this
type of nutrition. |
All animals and fungi have this type of
nutrition. |
Q NO 6:-Where do plants get
each of the raw materials required for photosynthesis?
ANS:- The following raw materials are
required for photosynthesis:
→ Carbon Dioxide: Plants get CO2 from atmosphere through stomata.
→ Water: Plants absorb water from soil through roots and transport to leaves.
→ Sunlight: Sunlight, which is absorbed by the chlorophyll and other green
parts of the plant.
Q NO 7:-What is the role of the
acid in our stomach?
ANS:- Following are the roles of
acid in our stomach:→ The hydrochloric acid present in our stomach
dissolves bits of food and creates an acidic medium. In this acidic medium,
enzyme pepsinogen is converted to pepsin, which is a protein-digesting enzyme.
→ It also kills many bacteria and other microorganisms that enter along with
the food.
Q NO 8:-What is the function of
digestive enzymes?
ANS:- Digestive enzymes such as
amylase, lipase, pepsin, trypsin, etc. help in the breaking down of complex
food particles into simple ones. These simple particles can be easily absorbed
by the blood and thus transported to all the cells of the body.
Q NO 9:- How is the small
intestine designed to absorb digested food?
ANS:- The small intestine has
millions of tiny finger-like projections called villi. These villi increase the
surface area for more efficient food absorption. Within these villi, many blood
vessels are present that absorb the digested food and carry it to the blood
stream. From the blood stream, the absorbed food is delivered to each and every
cell of the body.
Q NO 10:-What advantage over an
aquatic organism does a terrestrial organism have with regard to obtaining
oxygen for respiration?
ANS:- Terrestrial organisms take up oxygen
from the atmosphere whereas aquatic animals obtain oxygen from water. Air
contains more O2 as compared to water. Since the content of O2 in
air is high, the terrestrial animals do not have to breathe faster to get more
oxygen. Therefore, unlike aquatic animals, terrestrial animals do not need
adaptations for gaseous exchange.
Q NO 11:- What are the different
ways in which glucose is oxidized to provide energy in various organisms?
ANS:- At first glucose (6 carbon
molecules) is broken in the cytoplasm of cells of all organisms. This process
yields a 3 carbon molecule compound called pyruvate.
Further break down of pyruvate takes place in different manners in different
organisms.
→
Anaerobic Respiration: This
process takes place in absence of oxygen, e.g. in yeast during fermentation. In
this case pyruvate is converted into ethanol and carbon dioxide.
→ Aerobic Respiration: In
aerobic respiration, breakdown of pyruvate takes place in presence of oxygen to
give rise 3 molecules of carbon dioxide and water. The release of energy in
aerobic respiration is much more than anaerobic respiration.
→ Lack of Oxygen: Sometimes,
when there is lack of oxygen, especially during vigorous activity, in our
muscles, pyruvate is converted into lactic acid (3 carbon molecule compounds).
Formation of lactic acid in muscles causes cramp.
Q NO 12:-How is oxygen and
carbon dioxide transported in human beings?
ANS:- Transport of Oxygen: The
respiratory pigments (haemoglobin) present in red blood cells takes up the
oxygen from the air to the lungs. They carry the oxygen to tissues which are
deficient in oxygen.
Transport of carbon
dioxide: Carbon Dioxide is more soluble in water. Hence, it is mostly
transported from body tissues in the dissolved form in our blood plasma to
lungs where it diffuses from blood to air in the lungs and then expelled out
through nostrils.
Q NO 13:-How are the lungs
designed in human beings to maximize the area for exchange of gases?
ANS:- Lungs contain millions of
alveoli which provide a surface for the exchange of gases. An extensive network
of blood vessels is present in the wall of the alveoli. By lifting our ribs and
flatten the diaphragm, the chest cavity becomes spacious. Air is sucked into
the lungs and alveoli. The oxygen from the breath, diffuses into the blood and
CO2 from the blood brought from the body, diffuses out into the
air.
Q NO 14:- What are the components of the transport system in human beings?
What are the functions of these components?
ANS:- The main components of the transport system in human beings are the
heart, blood, and blood vessels.
Heart pumps oxygenated blood
throughout the body. It receives deoxygenated blood from the various body parts
and sends this impure blood to the lungs for oxygenation.
→ Blood helps in the transport of oxygen, nutrients, CO2, and
nitrogenous wastes.
→ The blood vessels (arteries, veins, and capillaries) carry blood either away
from the heart to various organs or from various organs back to the heart.
Q NO 15:- Why is it necessary to
separate oxygenated and deoxygenated blood in mammals and birds?
ANS:- It is necessary to separate
oxygenated and deoxygenated blood to maintain efficient supply of oxygen into
the body. This system is essential in animals that have high energy need. For
example, animals like mammals and birds which constantly use this energy to
maintain their body temperature.
Q NO 16:-What are the
components of the transport system in highly organised plants?
ANS:- In highly organized plants,
there are two different types of conducting tissues - xylem and phloem. Xylem
conducts water and minerals obtained from the soil (via roots) to the rest of
the plant. Phloem transports food materials from the leaves to different parts
of the plant body.
Q NO 17:- How are water and minerals
transported in plants?
ANS:- Water and minerals are
transported through xylem cells from soil to the leaves. The xylem cells of
roots stem and leaves are interconnected to form a conducting channel that
reaches all parts of the plant. The root cells take ions from the soil. This
creates a difference between the concentration of ions of roots and soil.
Therefore, there is a steady movement of water into xylem. An osmotic pressure
is formed and water and minerals are transported from one cell to the other
cell due to osmosis. The continuous loss of water takes place due to
transpiration. Because of transpiration, a suction pressure is created as a
result of which water is forced into the xylem cells of roots. The effect of
root pressure for transportation in plants is more important in night while
during day time transpiration pull becomes the major driving force.
Q NO 18:- How is food transported in plants?
ANS:- Phloem transports food materials from
the leaves to different parts of the plant. The transportation of food in
phloem is achieved by utilizing energy from ATP which helps in creating osmotic
pressure that transport food from the area of high concentration to low
concentration.
Q NO 19:- Describe the structure and
functioning of nephrons.
ANS:- Nephrons are the basic
filtering units of kidneys. Each kidney possesses large number of nephrons,
approximately 1-1.5 million. The main components of the nephron are glomerulus,
Bowman's capsule, and a long renal tubule.
Functioning of a nephron:
→ The blood enters the kidney through the renal artery, which branches into
many capillaries associated with glomerulus.
→ The water and solute are transferred to the nephron at Bowman's capsule.
→ In the proximal tubule, some substances such as amino acids, glucose, and
salts are selectively reabsorbed and unwanted molecules are added in the urine.
→ The filtrate then moves down into the loop of Henle, where more water is
absorbed.
→ From here, the filtrate moves upwards into the distal tubule and finally to
the collecting duct. Collecting duct collects urine from many nephrons.
→ The urine formed in each kidney enters a long tube called ureter. From
ureter, it gets transported to the urinary bladder and then into the urethra.
Q NO 20:- What are the methods
used by plants to get rid of excretory products?
ANS:- Plants can get
rid of excess of water by transpiration. Waste materials may be stored in the
cell vacuoles or as gum and resin, especially in old xylem. It is also stored
in the leaves that later fall off.
Q NO 21:- How is the amount of urine
produced regulated?
ANS:- The amount of urine produced
depends on the amount of excess water and dissolved wastes present in the body.
Some other factors such as habitat of an organism and hormone such as
Anti-diuretic hormone (ADH) also regulates the amount of urine produced.
Q NO 22:-The kidneys in human beings are
a part of the system for
(a) nutrition.
(b)
respiration.
(c)
excretion.
(d)
transportation.
► (c) excretion.
Q NO 23:-The xylem in plants
are responsible for
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.
► (a) transport of water.
Q NO 24:-The autotrophic mode of
nutrition requires
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the above.
► (d) all of the above.
Q NO 25:- The breakdown of
pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.
► (b) mitochondria.
Q NO 26:- How are fats digested
in our bodies? Where does this process take place?
ANS:- Fats are present in the form
of large globules in the small intestine. The small intestine receives the
secretions from the liver and the pancreas. The bile salts (from the liver)
break down the large fat globules into smaller globules so that the pancreatic
enzyme lipase can easily act on them. This is referred to as emulsification of
fats. This process takes place in the small intestine.
Q NO 27:- What is the role of saliva
in the digestion of food?
ANS:- The role of saliva in the
digestion of food:
→ It moistens the food for easy swallowing.
→ It contains a digestive enzyme called salivary amylase, which breaks down
starch into sugar.
Q NO 28:- What are the necessary
conditions for autotrophic nutrition and what are its by-products?
ANS:-
Autotrophic nutrition takes place through the process of
photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are
the necessary conditions required for autotrophic nutrition. Carbohydrates
(food) and O2 are the by-products of photosynthesis.
Q NO 29:- What are the differences between aerobic and anaerobic
respiration? Name some organisms that use the anaerobic
mode of respiration. ANS:-
|
Aerobic
respiration |
Anaerobic
respiration |
|
It occurs in the presence of O2. |
It occurs in the absence of O2. |
|
It involves the exchange of gases between
the organism and the outside environment. |
Exchange of gases is absent. |
|
It occurs in cytoplasm and mitochondria. |
It occurs only in cytoplasm. |
|
It always releases CO2 and H2O. |
End products vary. |
|
It always releases CO2 and H2O. |
End products vary. |
Q NO 30:- How are the alveoli designed to maximize
the exchange of gases?
ANS:- Alveoli
provide a surface for the exchange of gases. An extensive network of blood
vessels is present in the wall of the alveoli. By lifting our ribs and flatten
the diaphragm, the chest cavity becomes spacious. Air is sucked into the
lungs and alveoli. The oxygen from the breath, diffuses into the blood and CO2 from the blood brought from the body, diffuses out
into the air.
Q NO 31:-What
would be the consequences of a deficiency of hemoglobin in our bodies?
ANS:- Hemoglobin
is the respiratory pigment that transports oxygen to the body cells for
cellular respiration. Therefore, deficiency of hemoglobin in blood can affect
the oxygen supplying capacity of blood. This can lead to deficiency of oxygen
in the body cells. It can also lead to a disease called anaemia.
Q NO 32:- Describe
double circulation in human beings. Why is it necessary?
ANS:- During
a single cycle blood goes twice in the heart which is known as double
circulation. It is necessary in human being to separate oxygenated and
de-oxygenated blood because this makes their circulatory system is more
efficient and helps in maintaining constant body temperature.
Q NO 34:- What are
the differences between the transport of materials in xylem and phloem?
ANS:-
|
Aerobic respiration |
Anaerobic respiration |
|
Xylem
tissue helps in the transport of water and minerals. |
Phloem
tissue helps in the transport of food. |
|
Water
is transported upwards from roots to all other plant parts. |
Food
is transported in both upward and downward directions. |
|
Transport
in xylem occurs with the help of simple physical forces such as transpiration
pull. |
Transport
of food in phloem requires energy in the form of ATP. |
Q NO 35:- Compare the functioning of alveoli in the
lungs and nephrons in the kidneys with respect to their structure and
functioning.
ANS:-
|
Alveoli |
Nephrons |
|
Structure |
Structure |
|
Alveoli
are tiny balloon-like structures present inside the lungs. |
Nephrons
are tubular structures present inside the kidneys. |
|
The
walls of the alveoli are one cell thick and it contains an extensive network
of blood capillaries. |
Nephrons
are made of glomerulus, bowman’s capsule, and a long renal tube. |
|
Function |
Function |
|
The
exchange of O2 and CO2 takes place between the blood of the capillaries that
surround the alveoli and the gases present in the alveoli. |
The
blood enters the kidneys through the renal artery. The blood is entered here
and the nitrogenous waste in the form of urine is collected by collecting
duct. |
|
Alveoli
are the site of gaseous exchange. |
Nephrons
are the basic filtration unit. |
UNIT XII : Control and Coordination
TOPIC :- CONTROL & CO-ORDINATION
(BIOLOGY)
CO-ORDINATION:-
The working together of various organs of the body of an organism in a proper
manner to produce
appropriate reaction to a stimulus is called coordination. All the
living organisms respond to the stimuli
which occur in the environment around them. Response to any stimuli is the
characteristic feature
of a living thing.
HARMONE:- Harmones are the chemical substances secreted from
endocrine glands which co-ordinate the activities of living things.
STIMULI:-The changes in the environment to which the organisms
respond &react are called stimuli.
Living
organisms shows response to stimuli like heat, cold, sound, smell, touch, water
etc.
The response of
organism to a stimuli is usually in the form of some movement of their body
part. e.g If a
man touches a very hot utensil accidently, he quickly
pulls his hand away from the hot utensil. Here hotness is the Stimulus &
the man reacts by moving his hand away from the hot utensil. The response to a
stimuli is a characteristic property of the living organisms. All the living
organisms show sensitivity to changes in the environment stimulus and are of
two types:
CO-ORDINATION IN PLANTS
Animals have a nervous system for controlling the
activities of the body, but plants don’t have nervous system.Plants can respond things like
Light,Gravity,Chemicals,Water & Touch by the action of hormones in them.
Plants cant response quickly to any
stimuli because they don’t have Nervous system like in animals.
The function of control & co-ordination in plants
is performed by the chemical substances called harmones. Plant harmones are
also called as Phytoharmones.(Phyto=plant)
There are four major plant harmones and are:-
(A) AUXIN
(B)GIBBERELLIN
(C)CYTOKININ
(D)ABSCISIC
ACID
Among these four Auxin ,Gibberellin & Cytokinin
promotes enlargement in the plant parts.Cytokinin also promotes the opening of
Stomata. Fruit growth is also by these three harmones.Where as Abscisic acid
inhibits plant growth and is also
responsible for closing of Stomata. This harmone is also responsible for falling
of leaves.
TROPISMS
A growth movement of a plant in responsible to an
external stimulus in which the direction
of stimulus determines the direction of response is called Tropism.Tropism is
of two types and are:-
If the
growth of a plant part is towards the stimulus it is called positive tropism.
If the
growth of a plant part is away from the stimulus ,then it is called as Negative
tropism.
There
is generally five stimuli in the environment. These five stimuli give us five
types of tropisms and are :-
(1) Stimulus by light is called Phototropism.
(2) Stimulus by gravity is called
Geotropism.
(3) Stimulus by water is called
Hydrotropism.
(4)
Stimulus by Chemical is called Chemotropism.
(5) Stimulus
by Touch is called Thigmotropism.
(1) STIMULUS BY LIGHT:-The movement of a plant part in response to light is
called phototropism. If a plant part move towards the light it is called
positive Phototropism.
(2) STIMULUS
BY GRAVITY:-The movement of a
plant part in response to light is called
Geotropism. If a plant part moves towards gravity it is called positive
geotropism & if the plant part moves away from the gravity then it is
called negative geotropism.
(3)
STIMULUS BY WATER:-The movement
of a plant part in response to water is called hydrotropism. If the plant part
moves towards water it is called positive hydrotropism & if the plant part
moves away from the water then it is called negative hydrotropism.
(4)
STIMULUS BY CHEMICALS:-The
movement of a plant part in response to a chemical stimuli is called
chemotropism. If the plant part moves towards chemicals it is called positive
chemotropism & if the plant part moves away from the chemicals then it is
called negative chemotropism.
(5)
STIMULUS BY TOUCH:-If the plant
part moves in response to the touch of an object is called Thigmotropism. If
the plant party moves towards the external touch it is called positive
thigmotropism & if the plant part moves away from the touch then it is
called negative thigmotropism.
CO-ORDINATION IN ANIMALS
The control
& co-ordination in in animals takes place through Nervous system as well as
Endocrine system .Nervous system is made upof nerve cells called Neurons where
as endocrine system is made up of endocrine glands.
SENSE
ORGANS:-We receive a variety of
information from the environment around us through these sense organs.e.g Eyes,
Ears, Nose, Tongue & Skin are some examples of sense organs. Sense organs
contain Receptors.
RECEPTOR:- A receptor is a cell or a group of cells in sense
organ which is sensitive to a particular type of stimulus such as light, heat,
pressure etc.
A receptor detect stimulus. e.g eyes contain receptors called
photoreceptors which detect light. Ears
contain receptors called Phonoreceptors which detect sound. Nose contains
receptors called Olfactory receptors which detect smell.Tongue contains
receptors called Gustatory receptors which detect taste. Skin contains
receptors called Thermoreceptors which detect heat or cold.
EFFECTOR:-
An effector is a part of the body
which can response to a stimulus according to the instructions sent from the
nervous system. The effectors are mainly muscles of our body. All our muscles
response to stimuli sent fro the nervous system.
CO-ORDINATION IN HUMAN BEINGS
There are two systems of control &
co-ordination in human beings & they are
(1) NERVOUS
SYSTEM
(2)
ENDOCRINE SYSTEM
In human beings Nervous system & Endocrine system
work together to control & co-ordinate all
our activities such as physical actions , Thinking & also emotional
behaviour.
(1) NERVOUS
SYSTEM:- The function of nervous
system is to co-ordinate the activities of our body. It is the nervous system
of our body which make together working of other body systems. The nervous system
also co-ordinates things like heart beat& breathing. The nervous system
receives information from the surroundings, process it, interprets it &
then responds accordingly.
Types of
Nerves:- there are three types of Nerves on the basis of location
& are:
a) Cranial
Nerves:- these are those nerves which arise from brain directly and are
responsible for head region. There are 12 pairs of cranial nerves. among these 12 pairs only one extends
upto abedomen and is called as vagus.
Cranial nerves may be sensory nerve as well as motor nerve.
b) spinal
Nerves:- these are those nerves which arises from spinal cord and are
responsible for skin & muscular tissue. There are 31 pairs of spinal
nerves. These may also be sensory nerves as well as motor nerves.
c) Viceral Nerve:- these are those nerves which also
arises from spinal cord but are responsible for visceral organs (internal
organs). These may also be sensory nerves as well as motor nerves.
DIAGRAM SHOWING
HUMAN NERVOUS SYSTEM
NEURON (THE BASIC
UNIT OF NERVOUS SYSTEM)
Neuron is the basic structural & functional unit of nervous
system.Nervous system is made upof special cells called Neurons.Neuron is the
largest cell in the Human body.The function of the neuron is to carry the
message in the
body in the form of electrical impulses. A neuron has three components and
are:-
(A) Cell body
(B) Dendrites
(C) Axon
Cell body
is the inflimated part of the neuron which contains cytoplasm and a nucleus.The
short fibres
which arise from the cell body are called dendrites ,
where as the longest fibre on the cell body of a neuron is called Axon.the Axon
has an insulating and protective sheath called Myelin sheath.
The
dendrites pick up the electrical impulse (message) from the receptors.
Dendrites pass this message to the cell body and then along the axon. The Axon
Pass the impulse to the another Neuron through a junction called Synapse.
(Synapse is the microscopic gap between two neurons)
DIAGRAM SHOWING A TYPICAL NEURON
Neurons are of three types and are:-
(I) Sensory Neurons
(II) Motor
Neurons
(III) Relay
Neurons
(I)
Sensory Neurons:-They passes
electrical impulses from receptors towards the spinal cord and then brain.
(II)
Motor Neurons:- They transmit electrical
impulses from the Brain towards the muscles (effectors).
(III) Relay
Neurons:- They occur in the brain
and spinal cord and they serve between Sensory neurons and Motor Neurons.
REFLEX ACTION
AND REFLEX ARC
REFLEX
ACTION:- The simplest form of
response in the nervous system is the reflex action. Reflex action is a rapid, automatic and involuntary response to
a stimulus, which is not under the voluntary action of brain. Reflex action is
one which we perform automatically. E.g
moving our hand immediately away on touching a
hot plate.
REFLEX
ARC:- The pathway taken by
electrical impulse in a reflex action is called the reflex arc.
DIAGRAM SHOWING REFLEX ACTION &
REFLEX ARC
CENTRAL NERVOUS SYSTEM
The central nervous system consists of Brain and
Spinal Cord. The job of the central nervous system is to
collect all the information from all the receptors in our body.This information is
added together before messages are sent out to the effectors. In this way the
best action can be taken in a particular set of circumstances.
BRAIN
Human
brain is a soft, whitish, large & slightly flattened organ present in a
bony box called cranium. It is the highest coordinating organ & centre of thinking. The brain is surrounded by three membranes called Meninges, which
help to protect it. The meanings present over brain are:
1) Outer membrane called Dura matter.
2) Middle membrane called Arachnoid membrane.
3) inner membrane called Pia matter.
Between
these meninges is present a transparent fluid called cerebro-spinal fluid,
which protects the brain from mechanical shocks. Twelve pairs of cranial nerves
arise from brain.
The
brain is devided into three main regions.
a) Fore
brain (Prosencephalon)
b) Mid brain
(Mesencephalon)
c) Hind
brain (Rhombencephalon)
a) Fore
brain:- Also called as
prosencephalon. This region consists mainly of cerebrum & is the main
thinking part of the brain. Cerebrum of fore brain. Cerebrum of force brain is
differentiated into two hemispheres called cerebral hemispheres. Both cerebral
hemispheres are highly folded to form gyri and sulci. Each cerebral hemisphere
( Forebrain) is devided into four lobes
i) Frontal lobe
ii) parietal lobe
iii) occipital lobe
iv) temporal lobe.
Forebrain
is the main thinking part of the brain. It is the site for learning,
intelligence, personality and memory. All the voluntary actions of the body are
coordinated by the forebrains.
b) Mid
brain:- Also called Mesencephilon
& his two parts.
I) Optic lobe
ii) Cerebral penduncles
Mid
brain controls reflex action of the head
c) Hind
brain:- Also called as Rhomencephilon
& his three parts.
I) Cerebellum
ii) Pons varolli
iii) Medula oblongata
Hind
brain controls all the involuntary action of the body, like respiration,
heartbeat, blood circulation and peristaltic movement of the food pipe etc.
DIAGRAM SHOWING
BRAIN & ITS PARTS
SPINAL CORD
Spinal cord
is a cylindrical structure. The spinal cord begins from brain and extends
downwards. It is enclosed in a bony cage called Vertebral column. Spinal cord
is surrounded by three coverings called
Meninges. About 31 pairs of nerves arise from the
spinal cord. The spinal cord is concerned with conduction
of electrical impulses from receptors towards brain.
(2) ENDOCRINE SYSTEM:- A group of
endocrine glands which produces various harmones is called an Endocrine system.
The endocrine system is also called as Harmonal system. The endocrine system in
our body consists of a number of glands which store and release chemicals
called harmones. There are a large number
of endocrine glands in the human body and are:-
PINEAL GLAND
HYPOTHALAMUS GLAND
PITUITARY GLAND
THYROID GLAND
PARATHYROID GLAND
THYMUS GLAND
PANCREAS
ADRENAL GLAND
TESTES (MALES)
OVARIES (FEMALES)
Different endocrine glands make different types of harmones. The working
of endocrine glands is controlled by our nervous system.The harmones produced
in our body act as messengers between the
nervous system and the organs of our body.
PINEAL
GLAND:- Pineal gland is present
in brain,& has no known function.
HYPOTHALAMUS:- Hypothalamus gland is present in brain .Hypothalamus
produces releasing harmones and Inhibitory harmones. Hypothalamus controls the
pituitary harmones.
PITUITARY
GLAND:- Pituitary gland is
present just below the brain. It produces a number of harmones. For example
growth harmone is released by the pituitary gland.
THYROID
GLAND:- Thyroid gland is attached
to the wind pipe. It produces a harmone called Thyroxine which
is made upof iodine.The function of Thyroxine harmone
is to control the rate of metabolism of carbohydrates, fats & proteins in
the body. Deficiency of Iodine in our food leads to deficiency of Thyroxine
harmone which ultimately causes a disease known as Goitre. So, it is advised to
use iodised salt.
PARATHYROID
GLAND:- Parathyroid glands are
embedded in Thyroid gland and are four in number.They produces a harmone called
Paratharmone.
THYMUS
GLAND:- Thymus gland lies in the
lower part of the neck. They secrete a harmone called Thymus harmone which
develops our immune system.
PANCREAS:- The pancreas is present just below the stomach. It
secrets a harmone called Insulin. The function of insulin harmone is to lower
the blood sugar level in the body. Deficiency of Insulin harmone in the blood causes a
disease known as Diabetes. Patients with diabetes are treated by giving insulin
so as to maintain the blood sugar level.
ADRENAL
GLAND:- Adrenal glands are
present on the top of two kidneys. Adrenal glands secrete harmone called
Adrenaline harmone. Adrenaline harmone is also called as emergency harmone
because this harmone
is released
more during any emergency and also during frightened condition.
TESTES:- Testes are the glands which are present only in males.
Testes secrete male sex harmone called
Testosterone. The function of testosterone harmone is to develop the male sex
organs.
OVARIES:- Ovaries are the glands which are present only in
females. Ovaries secrete female sex harmones called Oestrogen &
Progestrone. The function of Oestrogen harmone is to develop female sex organs.
Where
as the function of
Progestrone harmone is to maintain the uterus changes in Menstrual
cycle.
DIAGRAM SHOWING ENDOCRINE
GLANDS
TEXTUAL QUESTIONS
Q NO 1:-What is the
difference between a reflex action and walking?
ANS:- A reflex action is voluntary action which is rapid
and automatic response to stimuli while walking
is a voluntary action which requires our thinking and is in our control.
Q NO 2:- What happens
at the synapse between two neurons?
ANS:- A synapse is a gap between the two neurons. At
synapse the electrical signals converted into chemicals that can easily cross
over the gap and pass on to the next neurons where it again is converted into
electrical signals.
Q NO 3:- What part of
the brain maintains posture and equilibrium of our body?
ANS:- Cerebellum.
Q NO 4:- How do
we detect the smell of an agarbati?
ANS:- When the smell of agarbati reaches to our nose then
the Olfactory receptors present in our nose
detects it
sends this information to fourbrain in the form of electrical signals.Fourbrain
interprets this information as the smell of agarbati where it is already
stored.
Q NO 5:- What is the
role of brain in reflex action?
ANS:- Brain has no direct involument in reflex action. It
is mainly controlled by spinal cord as these actions not require thinking and
are very quick actions.
Q NO 6:-What are
plant harmones?
ANS:- Plant harmones are the chemicals which are secreted
within the plant and are also known as phytoharmones. Plant harmones regulate
the growth and development of the plant. E.g of the plant
harmones are Auxin, Giberellin, Cytokinin, abscisic
acid.
Q NO 7:- How is the
movement of leaves of the sensitive plant different from the movement of a shoot
towards light?
ANS:- The movements of the leaves of the sensitive plant
are touch sensitive and independent of growth
while the movement of the shoot towards light is
growth related and known as phototropism.
Q NO 8:- Give an
example of a plant harmone that promotes growth?
ANS:- Auxin.
Q NO 9:- How do auxins
promote the growth of a tendril around a support?
ANS:- When tendrils come in contact with any support the
part of the tendril in contact with the object does not grow as rapidly as the
part of the tendril away from the object. This is called by the action of auxin
harmone.Less auxin occurs on the side of contact as compared to the free side
as a result ,auxin promotes growth on the free side and the tendrils coil
around the support.
Q NO 11:- How does
chemical co-ordination take place in animals?
ANS:- Chemical co-ordination takes
place in animals with the help of harmones. Harmones are chemicals that are
secreted by the endocrine glands. Harmones regulate the overall growth and
development of animals.
Q NO 12:- Why is the use
of iodised salt advisable?
ANS:- Iodine stimulates the thyroid gland to produce thyroxine
harmone.Thyroxine harmone regulates carbohydrate , fat & protein metabolism
in our body. Defeicency of this harmone results in the enlargement
of the thyroid gland. This can lead to Goitre ,
therefore iodised salt is advised for normal functioning of thyroid gland.
Q NO 13:- How does our
body respond when adrenaline is secreted into the blood?
ANS:- When someone is in danger or any emergency then
adrenal glands secrete adrenaline harmone. It is secreted directly into the
blood and is transported to different parts of the body. It speeds up the heart beat and hence supplies more oxygen to
the muscles. This results in increasing
breathing rate and blood pressure which enable them to fight with such urgent situation.
Q NO 14:- Why are
some patients of diabeties treated by giving injection of insulin?
ANS:- Diabetes is caused due to less or no secretion of
insulin harmone by pancreas, In such a person blood sugar level is high .
Insulin maintains the blood sugar level. Thus patients suffering from diabetes
are given insulin injection to control there blood sugar level.
Q NO 15:- How do
Auxins promote the growth of a tendril around a support?
ANS:- When tendrils
come in contact with any support, the part of the tendril in contact with the
object does not grow as rapidly as the part of the tendril away from the
object. This is caused by the action of auxin harmone. Less auxin occurs on the
side of contact as compared to the free
side as a result , auxin promotes growth on the free side and the tendrils coil
around the support.
their blood sugar level.
Q NO 16:-
(I) Which of the following is a plant
harmone?
ANS:- Cytokinin
(II) The gap between two neurons is called
as?
ANS:- Synapse
(III) The brain is responsible for?
ANS:- All of the above.
Q NO 17:-
What is the function of receptors in our body? Think of situations
where receptors don’t work properly.
What problems are likely to arise?
ANS:- Functions of
receptors are:-
(a) They sense the external stimuli such as heat
or pain.
(b) They also trigger an impulse in the sensory
neuron which sends message to the
spinal
cord.
When the
receptors are damaged, the external stimuli transferring signals to the brain
are not felt. For e.g in the case of damaged receptors, if we accidently touch
any hot object then our hands might get burnt as damaged receptors can’t
perceive the external stimuli of heat and pain.
Q NO 18:- Draw the
structure of a neuron and explain its function?
ANS:-
Functions of the three parts of the neuron
are:-
(i) Axon:- It conducts messages away from the
cell body.
(II) Dendrite:- It receives information from axon of
another neuron and conducts
the
messages towards the cell body.
(III) Cell body:- It contains nucleus,
Mitochondria, and other organells. It is mainly
concerned
with the maintenance and growth.
Q NO 19:- How does
Phototropism occur in plants?
ANS:- The growth movements in plants in response to light
stimulus is known as phototropism. The shoots show positive phototropism and the roots show
negative phototropism, This means that the shoots bend towards the source of
light where as the roots bend away from the light source. E.g the flower head
of sunflower is positively phototropic and hence it moves from east to west
along with the sun.
Q NO 20:- Which
signals will get disrupted in case of a spinal cord injury?
ANS:- In case of a spinal cord injury, the signals coming from the nerves as well as the
signals coming to the receptors will be disrupted. As both these signals meet
in a bundle in spinal cord . so there is any spinal cord injury then both these
signals are disrupted.
Q NO 21:-
How does chemical co-ordination occur in plants?
ANS:- Chemical co-ordination occurs in plants with the help
of plant harmones. Different plant harmones help to co-ordinate growth , development
, responses to the environment . they are synthesized at places away from where
they act and diffuse to the area for action, e.g Auxin promotes cell growth ,
Giberellin promote stem growth, Cytokinin promote cell division and Abscisic
acid inhibits growth and its effects include
wilting
of leaves.
Q NO 22:- What is the
need for a system of control and co-ordination in an organism?
ANS:- There are various organs in an organism. These
organs must be carefully controlled and co-ordinated for the survival of an
organism. In the body of an organism various harmones are secreted from the
glands of the endocrine system. These harmones are responsible for the overall
growth and development of an organism, and all others like voluntary and
involuntary actions are controlled by central nervous system.
Q NO 23:-
How are involuntary actions and reflex actions different from each
other?
ANS:- Involuntary action is the set of muscle movement
which don’t require thinking. But it is controlled by brain for example beating
of heart beat. Reflex action is rapid is rapid and spontaneous action in
response to any stimulus. E.g closing of eyes immediately when bright light is
focused.
Q NO 24:-
Compare and contrast nervous and hormonal mechanisms for control and
co-ordination in animals?
ANS:-
|
NERVOUS
SYSTEM MECHANISM |
HARMONAL
SYSTEM MECHANISM |
|
It consists of nerve impulses
between CNS and brain. |
It consists of endocrine system
which secretes harmones |
|
The axons and dendrites transmit the
information through a co-ordinated effort. |
The information is transmitted
through blood |
|
The flow of information is rapid and
the response is quick. |
The information travels slowly and
the response is slow. |
|
Nerve impulses are not specific in
their action. |
Each harmone has specific action. |
|
Effects are short lived |
It has prolonged effects. |
Q NO 25:-What is
the difference between the manner in which movement takes place in a sensitive
plant and the movement of our legs?
ANS:-
|
MOVEMENT IN SENSITIVE PLANT |
MOVEMENT
IN OUR LEGS |
|
The movement in a sensitive plant is response to
stimulus which is involuntary action. |
Movement in our legs is a voluntary action |
|
No special tissue is there for the transfer of message. |
A complete system CNS is there for the transfer of
information |
|
Plant cells don’t have specialized protein for the
movements |
Animal cells have specialized protein which help
muscles to contract. |
UNIT XIII : How do Organisms Reproduce
UNIT XIV : Genetics and Heredity
TRAIT:- Character of
any living organism like height, complexion, shape of hair, color of eyes, and
shape of nose and chin etc are called traits or characters. They are of two types
and are:-
(A).INHERITED
TRAITS:-Inherited traits are those traits which are obtained from the
parents and pass from generation to generation.
(B).ACQUIRED
TRAITS:-The acquired traits are those traits which are developed during
the life of an organism and these die with the death of an organism.
HEREDITY:- Transmission
of characters from parents to their off springs is called Heredity.
VARIATION:- The
differences in the characters or traits among the individuals of same species
is called variation. E.g some people are tall and some are dwarf, In some
individuals Earlobe is free and in others earlobe is attached. Variation is
necessary for Evolution. The great advantage of variation to a species is that
it increases the chance of its survival in a changing environment.
GENETICS:- Genetics is
the branch of biology that deals with the study of heredity and variations. The
term genetics was coined by William Bateson in 1906.
CHROMOSOME:- Chromosome
is a thread like structure formed of DNA which carries the genes and is present in the nucleus of a cell .In human
beings they are 46 in number.
GENE:-Essential
fragment of DNA of a chromosome is called a gene. A gene controls a specific character of an organism. Genes
are bridges of heredity which carry characters from parents to their off springs
during reproduction.
ALLELE:-Alternative
forms of gene; denoted by the same letter of groups; e.g. W and w; alleles
govern the contrasting forms of the same trait.
HOMOZYGOUS:-An individual that has two copies of the same alleles, e.g. WW or
ww.
HETEROZYGOUS:- An individual that has two different alleles of a gene, e.g. Ww.
ACCUMULATION
OF VARIATIONS DURING REPRODUCTION: -
Asexual reproduction involves single parent. When a single
individual reproduces asexually, the resultant two individuals again after some
time reproduce to form four individuals. In this way, large number of
individual are formed after many generations. All these individuals would be
similar. However, there would be only very minor differences between them.
These minor differences arise due to inaccuracies in DNA copying. Asexual
reproduction generates little diversity.
Sexual
reproduction, on the other hand, generates even greater diversity. This is so
because sexual reproduction involves two parents (father and mother) and every
offspring receives some characters of their parents (father and mother), they
show distinct differences (variations) among themselves as well as from their parents.
MENDEL’S EXPERIMENT
Gregor Johan Mendel (1822-1884) is known as the father of
genetics. Mendel had conducted breeding experiments on garden pea.
Mendel choose garden pea (Pisum sativum) because the pea plant is
small, Self pollinated, easy to grow, cross bred artificially and have
contrasting characters. This plant, being bisexual, is self-fertilizing in
nature but can be easily cross pollinated experimentally. It reproduces a large
number of offspring and completes its life cycle in one season.
Mendel selected seven visible characters, each with two
contrasting traits.
|
S.No. |
Character. |
Contrasting Traits. |
|
|
|
|
Dominant. |
Recessive. |
|
1. |
Plant size or height. |
Tall. |
Dwarf. |
|
2. |
Position of flower on the stem. |
Axial. |
Terminal. |
|
3. |
Color of unripe pod. |
Green. |
Yellow. |
|
4. |
Shape of pod. |
Inflated. |
Constricted. |
|
5. |
Shape of seed. |
Round |
Wrinkled. |
|
6. |
Color of seed. |
Yellow. |
Green. |
|
7. |
Color of flower. |
Violet. |
White. |
From his studies in pea, Mendel proposed the following two laws of
genetics:
1. Law of Segregation and
2. Law of independent Assortment.
Mendel’s Experimental Technique:- Mendel
conducted breeding experiments in three steps:
(i) Selection of pure parent plant (plants producing similar
traits in every generation).
(ii) Production of first generation of plants by crossbreeding
(hybridization).
(iii) Raising second and subsequent generations by self
fertilization of hybrids.
(1).MONOHYBRID
CROSS:- A breeding experiment dealing with a single character is called a
monohybrid cross.
In this experiment, Mendel crossed round seeds with another having
winkled seeds. The seeds resulting in F1 generation were all round
and the seeds produced by selfing of F1
plants, were three seeds round shaped and one seed of wrinkled shaped. On the
basis of these findings Mendel proposed the law of segregation which states
that the two alleles separate and pass into different gametes, producing two
different types of gametes in equal frequencies; this is known as segregation.
The Phenotypic ratio of F2 generation is 3:1 and the genotypic ratio of F2
generation is 1:2:1.
Some
basic terms:
*
Dominant and recessive allele:- Dominant allele is that allele which shows expression itself and this
allele is referred to as the dominant allele. Recessive allele is that allele
which remains silent or don’t shows its expression and is called as recessive
allele.
* Phenotype: - The observable characteristics of an organism; may refer to a
single character or a group of characters, e.g. round and wrinkled (pea seed).
* Genotype: - The genetic make-up of an organism; may refer to one or more
genes; e.g. RR, Rr and rr.
* Homozygous: - An individual that has two copies
of the same alleles, e.g. RR or rr.
* Heterozygous: - An individual that has two different
alleles of a gene, e.g. Rr.
Mendel’s
monohybrids cross.
|
|
R |
R |
|
R |
RR Round |
Rr Round |
|
r |
Rr Round |
rr wrinkled |
The ratio came out to be 3:1 as 3 out of 4 were round and 1 out of
4 was wrinkled.
2.
MENDEL’S DIHYBRID CROSS: - Based on dihybrid cross Mendel proposed law of independent
assortment.
A breeding experiment dealing with two characters at the same time
is called a dihybrid cross.
Let us consider a cross in which plants producing round and yellow
seeds were crossed with plants producing wrinkled and green seeds. The F1 generations
were all yellow and round seeded, suggesting that yellow is dominant over green
and round seed is dominant over wrinkled seed.
When these F1s are selfed, Mendel postulated that the
segregation of one pair of unit factors will occur independently of the other
pair or they will assort independently.
Accordingly, the gametes must carry all possible combinations of
the unit factors in equal frequency. In this example gametes with random
distribution of unit factors will give following combinations;
(i) Yellow & Round
(ii)Yellow & Wrinkled
(iii) Green & Round
(iv) Green & Wrinkled.
These combinations will result in a phenotypic ratio of 9:3:3:1
and this ratio are same for all dihybrid crosses.
Mendel’s dihybrids cross.
Parent generation Round Yellow
Wrinkled green
RRYY
rryy
Separation of gametes ↓ ↓
Gametes Formed RY × ry
F1 generation RrYy
F1 generation cross
Separation of gametes
Gametes
formed RY Ry
rY ry RY Ry
rY ry
Now in table, Fusion of gametes of F1
generation & formation of F2 generation
|
|
RY |
Ry |
rY |
ry |
|
RY |
RYRY Round
Yellow |
RYRy Round
Yellow |
RYrY Round
Yellow |
RYry Round
Yellow |
|
Ry |
RyRY Round
Yellow |
RyRy Round
Green |
RyrY Round
Yellow |
Ryry Round
Green |
|
rY |
rYRY Round
Yellow |
rYRy Round
Yellow |
rYrY Wrinkled
Yellow |
RYry Wrinkled
Yellow |
|
Ry |
ryRY
Round
Yellow |
ryRy Round
Green |
ryrY Wrinkled
Yellow |
Ryry Wrinkled
Green |
In F2 generation the Phenotypic ratio is as 9:3:3:1
Round & Yellow = 9
Round & Green = 3
Wrinkle & Yellow = 3
Wrinkled & Green = 1
Thus, the ratio of all dihybrid crosses is 9:3:3:1.
GENE:
-
This sequence of bonding of nitrogenous bases constitute gene i.e. the segment
of DNA is known as gene and this sequence contains a code for protein synthesis
and every protein has specific sequence of nitrogenous bases. Thus gene is
known as the unit of inheritance.
These sequences when inherited, actually inherits trait and thus
traits are expressed in organisms.
CHROMOSOMAL
BASIS OF SEX DETERMINATION
It refers to the condition where the genes involved in the sex
determination are located on specific chromosomes known as the sex chromosomes.
The sex is determined by the last pair of chromosomes which is known as sex
chromosome, for example in human beings there are 23 pair of chromosomes. Out
of 23 pair 22 pairs are autosomal chromosomes and are same in both male and
female while as the last pair i.e. 23rd pair is different
in male and female and thus this pair determines sex, thus known as sex
chromosome.
The difference in chromosomes which determines the sex may be of
three types.
1. Difference in number.
2. Difference in shape.
3. Difference in size of the sex chromosome.
1.
Difference in Number: -
In grasshopper, the number of chromosomes in female is 24 i.e. 2n.
It has been observed that male grasshopper contains only 23 chromosomes i.e.
2n─1. This difference in number determines the sex. When spermatogenesis
occurs, 23 chromosomes separate in such a way that one of the sperm receives 12
chromosomes while the other receives only 11. On fertilization the number
becomes 24 in one and 23 in the other giving rise to female and male
grasshopper respectively.
2.
Difference in Shape: -
T.H. Morgan, a Noble Prize winner biologist selected Drosophila fruit fly for his experiments
on inheritance. He noted that there are 4 pairs of chromosomes in the nucleus
of Drosophila, 3 of the pairs are alike in male and female flies (Autosomes)
while one of the chromosomal pair differs in shape. The fourth pair is the pair
of Sex chromosomes. This 4th pair was found to be composed of Rod
shaped chromosomes in female flies while in male the 4th chromosome
pair was Hook shaped. This similar rod shaped chromosomes in female was
designated as X while hook shaped chromosomes in male as Y. Therefore female
contains XX pair of chromosomes and Male contains YY pair.
3.
Difference in Size: -
Human cells contain 23 pairs of chromosomes (i.e. 46 in whole) of
chromosomes. Out of these, 22 pairs are alike and are Autosomes while 23rd
pair is composed of sex chromosomes. In female this pair of sex chromosomes
contains two similar chromosomes while in male one of the chromosomes is
similar in size as of female and the other is smaller in size. The smaller
chromosome is labeled as Y and the chromosome similar to each of the female sex
chromosome is labeled as X. Therefore females are homozygous XX while males are
heterozygous XY.
ORIGIN:
Life:
-
Life is the inherent capacity of living organisms to utilize the outside
materials (light, water, gases, or food) for energy, growth and reproduction
through chemical reactions (metabolism) in a controlled manner.
Big
bang theory: - scientists believe that 10,000-20,000 million years ago the
universe consisted of a single piece of concentrated matter. The matter
exploded (Big Bang throwing out hydrogen atoms and related nuclei which became
organized into galaxies.
Cosmologists have estimated that the universe has approximately
100,000 million galaxies. All the galaxies appear to be moving away from one
another at great speeds, approaching the speed of light. In the galaxy, stars
are born and die continually. Our galaxy, the Milky Way galaxy, is just one of them.
All the stars that we can see with the naked eye belong to our galaxy. Our sun
is one such star, and along with the orbiting planets and there satellites, the
comets and asteroids, constitutes our solar system.
Origination
of solar system: - the prevalent view is that the solar system originated by the
gravitational contraction (condensation) of a cold cosmic cloud of dust and gas
called nebula. During condensation, this cloud began to rotate due to the
initial velocities of the particles brought together. As condensation and spin
continued, most of the mass concentrated near the centre and the flattened disc
broke into a number of whirling masses of smaller clouds. The sun was formed
from the dense centre. Condensation caused the temperature to increase and when
the temperature was high enough, nuclear reactions started and the new star
“sun” began to radiate energy. The planets, including the earth, were formed
from the cooler, less dense outer regions, almost in the same plane.
Condensation occurred in each of these smaller clouds, concentrating the
heavier elements at the centre.
THEORIES ON THE ORIGIN OF LIFE: -
There are
various theories about the origin of life on earth. Some are based on religious
views that is life had been created by some super natural power, the creator,
and others are based on other views, for example the theory of spontaneous
generation, cosmozoic or interplanetary theory, but the most accepted and
proven theory is Abiogenic or naturalistic or chemical origin of life.
EVOLUTION
The term
evolution literally means to ‘unroll’ or ‘unfold’. It refers to a gradual
change from one form to another since the beginning of life.
It refers to
gradual change from one form to another. Such a change in elements with time is
called inorganic evolution. However, gradual change in living organisms with
time since the beginning of life is termed organic (biological) evolution.
The concept
of organic evolution was first given by Charles Darwin which simply means
‘descent with modification’. This doctrine of organic evolution states that the
present-day complex organisms have originated from the earlier simpler forms of
life during the course of ages by the process of gradual change.
How evolution
occurs: -
1) Natural selection: -
It is the
phenomenon wherein nature, in wild, selects traits favourable to the species in
its environment. Thus, the natural selection is a creative process which uses
the variations and mutations as the raw materials from which better adapted
individuals with more chances of survival are obtained.
2) Genetic Drift: -
In small
populations, natural selection has less
role to play in fixing a gene or gene combination. In small populations
gene frequencies fluctuate purely by chance. This sudden drift of change in
gene frequency to one or other side is called genetic drift. This was proposed
by Sewall Wright and is also called Sewall Wright effect.
3) Isolation: -
Isolation or
segregation of individuals of a species into several populations or groups
under psychic, physiological or geographical factors is considered to be one of
the most important factors responsible for evolution.
Geographical isolation includes physical barriers like mountains, rivers, oceans and
long distances, which prevent interbreeding between related forms.
Physiological barriers help in maintaining the individuality of the species,
because these isolations do not permit the interbreeding among the individuals
of different species. All these lead to reproductive isolation.
Reproductive isolation: - The term reproductive isolation
refers to the mechanism which checks the population of two different species
from interbreeding. The productive isolation, thus, preserves the integrity of
a species by checking hybridization. It may, however, lead to the origin of new
species by accumulation of genetic variations in a population. Reproductive
isolation, thus, lets evolution to occur.
Types of reproductive isolation: -
4) Speciation: -
It is the
origin of new species from the existing one due to reproductive isolation of a
part of its population is called speciation. The microevolution refers to the
origin of new variants due to appearance of small but significant variations in
individuals that simply change the common characteristics (traits) of a
particular species only. The macroevolution, on the other hand, involves origin
of new species, genera and higher taxa.
1)
Morphological and Anatomical evidences: -
These are based on the external and internal features of the
different kinds of organisms. It includes the following features:
(i) Homologous organs:
-
The organs which perform different functions in different species but haves
similar basic structure and similar embryonic origin are called homologous
organs, e.g. forelimb of frog, forelimb of lizard, forelimb of bird and
forelimb of human being.
(ii) Analogous organs: - The organs
which are quite different in fundamental structure and embryonic origin but
perform same function and may superficially look alike in entirely different
species are called analogous organs, e.g. insect wing and bird wing.
Absolute
dating: - (Radioactive dating). Fossil or piece of fossil containing rock is
analyzed for content of uranium and lead, radioactive potassium and argon or
contents of radioactive carbon (14C). Carbon dating is meant for
calculating the age of recent fossil. Electron spin resonance is the earliest
technique to determine the age of the fossil directly without breaking any
part.
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ARTIFICIAL
SELECTION: - It is the process by which man selects trait(s) useful to him
for improving the qualities of domesticated plants and animals. It is
improved for beneficial to man. |
PROGRESS VS EVOLUTION
Evolution should not be equated with progress. It is not a
progress. It is like a branch of tree and not like a ladder. As every species
in the evolution have the characteristics which are missing in the higher
species. Thus, every species have its own characteristics and every species is
dependent on one another for different needs. If it should be considered as
progress then the higher species should have all the features and
characteristics of all the lower species and should never depend on the lower
species, but it is not so. Thus we can say that the evolution produces new
species but it is not a progress.
HUMAN
EVOLUTION
The human beings are closely related to chimpanzees but have not
evolved from them. But these species have a common ancestor long ago. This
common ancestor diverged into several forms and gave rise to human beings,
chimpanzees, and great apes like gorilla, organgutan etc.
The biological name given to human being is Homo sapiens (homo = man;
sapiens = wise). The human being
certainly is an animal, but an animal with unique characteristics. At a
biological level, the human being is not unique for strength, ability, speed or
endurance. Human beings also have a poorer sense of hearing, smell and vision
than many other animals. Yet we are special because we have highly evolved
brain and the skilled hands we possess. We are unique because we are tool
makers; we are not at the mercy of environment and we can substantially alter
the environment to suit our needs. Thus, we are now dominant species on earth.
The dominance of human beings on this earth started when man, the hunter and
gatherer, became a cultivator and herdsman. The discovery of agriculture, led
to settlements along river valleys and thus inturn led to establishment of
civilizations.
TEXTUAL QUESTIONS
Q
NO 1:-If a trait A exists in 10% of a population of an asexually reproducing
species and a trait B exists in 60% of the same population, which trait is
likely to have arisen earlier?
ANS:-Trait B because in asexual reproduction traits which are present in the
previous generation are carried over to next generation with minimal
variations. Trait B have higher percentage so it is likely to have arisen
earlier.
Q NO 2:-How does the creation
of variations in a species promote survival?
ANS:-Variations occur due to sexual reproduction and also due to
inaccurate copying of DNA. Depending on the nature of variations, different
individuals would have different kinds of advantages. For example, bacteria
variants which can withstand heat have better chances to survive in a heat wave
non-variant bacteria having no capacity to tolerate heat wave. Thus,
variations in a population of a species help in survival of a species.
Q NO 3:-How do Mendel's
experiments show that traits may be dominant or recessive?
ANS:-The trait which appears in all the members of F1 generation
and also in 75% numbers of F2 generation
obtained by self fertilization of F1 generation is dominant character.
The trait which does not appear in F generation but after self-fertilization of
F1 generation,
reappears in 25% of F2 generation
is known as recessive.
Q NO 4:-How do Mendel's
experiments show that traits are inherited independently?
ANS:-Mendel crossed pure breeding tall plants having round seeds with pure
breeding short plants having wrinkled seeds. The plants of F1generation
were all tall with round seeds indicating that the traits of tallness and round
seeds were dominant. Self breeding of F1yielded plants with
characters of 9 tall round seeded, 3 tall wrinkled seeded , 3 short round
seeded and one short wrinkled seeded. Tall wrinkled seeded and short round
seeded plants are new combinations which can develop only when the traits are
inherited independently.
Q NO 5:-A man with blood group A
marries a woman with blood group O and their daughter has blood group O. Is
this information enough to tell you which of the traits - blood group A or O -
is dominant? Why or why not?
ANS:- No. This information is not sufficient to determine which of
the traits - blood group A or O - is dominant. This is because we do not know
about the blood group of all the progeny.
Blood group A can be genotypically AA or AO. Hence, the information is
incomplete to draw any such conclusion.
Q NO 6:-How is the sex of the
child determined in human beings?
ANS:-In human beings, the females have two X chromosomes and the males have one
X and one Y chromosome. Therefore, the females are XX and the males are XY.
The gametes, as we know, receive half of the chromosomes. The male gametes have
22 autosomes and either X or Y sex chromosome.
Type of male gametes: 22+X OR 22+ Y.
However, since the females have XX sex chromosomes, their gametes can only have
X sex chromosome.
Type of female gamete: 22+X
Thus, the mother provides only X chromosomes. The sex of the baby
is determined by the type of male gamete (X or Y) that fuses with the X
chromosome of the female.
Q
NO 7:-What are the different ways in which individuals with a particular trait
may increase in a population?
ANS:-Individuals
with a particular trait may increase in a population as a result of the
following:
→ Natural selection: When that trait offers some survival advantage.
→ Genetic drift: When some genes governing that trait become common in a
population.
→ When that trait gets acquired during the individual's lifetime.
Q NO 8:-Why are traits acquired
during the life-time of an individual not inherited?
ANS:-This happens because an acquired trait involves change in
non-reproductive tissues which cannot be passed on to germ cells or the
progeny. Therefore, these traits cannot be inherited.
Q NO 9:- Why are the small
numbers of surviving tigers a cause of worry from the point of view of
genetics?
ANS:-The small number of members in a population of tigers do not allow large
number of variation to occur which are essential to survival of the species. A
deadly disease or calamity may cause death of all the tigers. The small number
of tiger also indicates that existing tiger variants are not well adopted to
the existing environment and may extinct soon.
Q NO 10:-What factors could lead to the rise of a new
species?
ANS:-Natural selection, genetic drift and acquisition of traits during the life
time of an individual can give rise to new species.
Q
NO 11:- Will geographical isolation be a major factor in the speciation of
a self-pollinating plant species? Why or why not?
ANS:-Geographical isolation can prevent the transfer of pollens
among different plants. However, since the plants are self-pollinating, which
means that the pollens are transferred from the anther of one flower to the
stigma of the same flower or of another flower of the same plant, geographical
isolation cannot prevent speciation in this case.
Q NO 12:-Will geographical
isolation be a major factor in the speciation of an organism that reproduces
asexually? Why or why not?
ANS:-No, because geographical isolation does not affect much in asexually
reproducing organisms. Asexually reproducing organisms pass on the parent DNA
to offsprings that leaves no chance of speciation. However, geographical
isolation works as a major factor in cross pollinated species. As it would
result in pollinated species. As it would result in accumulation of variation
in the two geographically separated population.
Q NO 13:-Give an example of
characteristics being used to determine how close two species are in
evolutionary terms.
ANS:-Feathers in some ancient reptiles like dinosaurs, as fossils indicate,
evolved to provide insulation in cold weather. However, they cannot fly with
these feathers later on birds adapted the feathers to flight. This means that
birds are very closely related to reptiles, since dinosaurs were reptile.
Q NO 14:-Can the wing of a
butterfly and the wing of a bat be considered homologous organs? Why or why
not?
ANS:-The wing of a butterfly and the wing of a bat are similar in function.
They help the butterfly and the bat in flying. Since they perform similar
function, they are analogous organs and not homologous.
Q NO 15:- What are fossils?
What do they tell us about the process of evolution?
ANS:-Fossils are the remains of organisms that once existed on earth.
They tell us about the development of the structures from simple structured to
complex structured organisms. They tell us about the phases of evolutions
through which they must have undergone in order to sustain themselves in the
competitive environment.
Q NO 16:-Why are human beings
who look so different from each other in terms of size, colour and looks said
to belong to the same species?
ANS:-A species is a group of organisms that are capable of interbreeding to
produce a fertile offspring. Skin colour, looks, and size are all variety of
features present in human beings. These features are genetic but also
environmentally controlled. Various human races are formed based on these
features. All human races have more than enough similarities to be classified
as same species. Therefore, all human beings are a single species as humans of
different colour, size, and looks are capable of reproduction and can produce a
fertile offspring.
Q NO 17:-In evolutionary terms,
can we say which among bacteria, spiders, fish and chimpanzees have a 'better'
body design? Why or why not?
ANS:-Evolution cannot always be equated
with progress or better body designs. Evolution simply creates more complex
body designs. However, this does not mean that the simple body designs are
inefficient. In fact, bacteria having a simple body design are still the most
cosmopolitan organisms found on earth. They can survive hot springs, deep sea,
and even freezing environment.
Therefore, bacteria, spiders, fish, and chimpanzees are all
different branches of evolution.
Q NO 18:- A Mendelian
experiment consisted of breeding tall pea plants bearing violet flowers with
short pea plants bearing white flowers. The progeny all bore violet flowers,
but almost half of them were short. This suggests that the genetic make-up of
the tall parent can be depicted as
(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw
► (c) TtWW
Q NO 19:- An example of
homologous organs is
(a) our arm and a dog's fore-leg.
(b) our teeth and an elephant's tusks.
(c) potato and runners of grass.
(d) all of the above.
► (b) our teeth and an elephant's tusks.
Q NO 20:- In evolutionary
terms, we have more in common with
(a) a Chinese school-boy.
(b) a chimpanzee.
(c) a spider.
(d) a bacterium.
► (a) a Chinese school-boy.
Q NO 21:-A study found that
children with light-coloured eyes are likely to have parents with
light-coloured eyes. On this basis, can we say anything about whether the light
eye colour trait is dominant or recessive? Why or why not?
ANS:-This information is not sufficient. For considering a trait as dominant or
recessive, we need data of at least three generations. This data is about only
two generations.
Q NO 22:- How are the areas of
study - evolution and classification - interlinked?
ANS:-Classification involves grouping of organism into a formal system based on
similarities in internal and external structure or evolutionary history.
Two species are more closely related if they have more characteristics in
common. And if two species are more closely related, then it means they have a
more recent ancestor.
For example, in a family, a brother and sister are closely related and they
have a recent common ancestor i.e., their parents. A brother and his cousin are
also related but less than the sister and her brother. This is because the
brother and his cousin have a common ancestor i.e., their grandparents in the
second generation whereas the parents were from the first generation.
With subsequent generations, the variations make organisms more different than
their ancestors.
This discussion clearly proves that we classify organisms according to their
resemblance which is similar to creating an evolutionary tree.
Q NO 23:-Explain the terms
analogous and homologous organs with examples.
ANS:-Homologous organs:-
are those organs which have the same basic structural design and origin but
have different functions.
For Example: The forelimbs of humans and the wings of birds look different
externally but their skeletal structure is similar.
Analogous organs:- are those
organs which have the different basic structural design and origin but have
similar functions.
For Example: The wings of birds and insects.
Q
NO 24:- Outline a project which aims to find the dominant coat colour in
dogs.
ANS:-Dogs have a variety of
genes that govern coat colour. There are at least eleven identified gene series
(A, B, C, D, E, F, G, M, P, S, T) that influence coat colour in dog.
A dog inherits one gene from each of its parents. The dominant gene gets
expressed in the phenotype. For example, in the B series, a dog can be
genetically black or brown.
Let us assume that one parent is homozygous black (BB), while the other parent
is homozygous brown (bb)
|
Bb |
BB |
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|
B |
B |
||
|
B |
Bb |
Bb |
|
|
B |
Bb |
Bb |
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In this case, all the offsprings will be heterozygous (Bb).
Since black (B) is dominant, all the offsprings will be black. However, they
will have both B and b alleles.
If such heterozygous pups are crossed, they will produce 25% homozygous black
(BB), 50% heterozygous black (Bb), and 25% homozygous brown (bb) offsprings.
|
B |
b |
|
|
B |
BB |
Bb |
|
b |
Bb |
Bb |
Q NO 25:-Explain
the importance of fossils in deciding evolutionary relationships.
ANS:-Fossil provide us evidence about
→ The organisms that lived long ago such as the
time period during which they lived, their structure etc.
→ Evolutionary development of species i.e., line
of their development.
→ Connecting links between two groups. For
example, feathers present in some dinosaurs means that birds are very closely
related to reptiles.
→ Which organisms evolved earlier and which
later.
→ Development of complex body designs from the
simple body designs.
Q NO 26:-What
evidence do we have for the origin of life from inanimate matter?
ANS:-The evidence for the origin of life from
inanimate matter, was provided through an experiment, conducted in 1953, by
Stanley L. Miller and Harold C. Urey. In experiment, they assembled an
atmosphere containing molecules like ammonia, methane and hydrogen sulphide,
but no oxygen, over water. This was similar to atmosphere that thought to exist
on early earth . This was maintained at a temperature just below 100°C and
sparks were passed through the mixture of gases to simulate lightning. At the
end of a week, 15% of the carbon from methane, had been converted to simple compounds
of carbon including amino acids which make up protein molecules and support the
life in basic form. Thus, amply suggesting that life arose afresh on earth.
Q NO 27:-Explain how sexual reproduction gives
rise to more viable variations than asexual reproduction. How does this affect
the evolution of those organisms that reproduce sexually?
ANS:-Sexual reproduction causes more viable
variations due to the following reasons:
→ Error in copying of DNA, which are not highly
significant.
→ Random segregation of paternal and maternal
chromosome at the time of gamete formation.
→ Exchange of genetic material between
homologous chromosomes during formation of gametes.
→ Accumulation of variations occured due to
sexual reproduction over generation after generation and selection by nature
created wide diversity.
In case of asexual reproduction, only the very
small changes due to inaccuracies in DNA copying pass on the progeny. Thus,
offsprings of asexual reproduction are more or less genetically similar to
their parents. So, it can be concluded that evolution in sexually reproducing
organisms proceeds at a faster pace than in asexually reproducing organisms.
Q NO 28:-How
is the equal genetic contribution of male and female parents ensured in the
progeny?
ANS:-In human beings, equal genetic contribution
of male and female parents is ensured in the progeny through inheritance of
equal number of chromosomes from both parents. There are 23 pairs of
chromosomes All human chromosomes are not paired. Out of these 23 pairs, the
first 22 pairs are known as autosomes and the remaining one pair is known as
sex chromosomes represented as X and Y. Females have a perfect pair of two X
sex chromosomes and males have a mismatched pair of one X and one Y sex
chromosome.
During the course of reproduction, as
fertilization process takes place, the male gamete (haploid) fuses with the
female gamete(haploid) resulting in formation of the diploid zygote. The zygote
in the progeny receive an equal contribution of genetic material from the
parents. Out of 23 pairs of chromosomes in progeny, male parent contributes 22
autosomes and one X or Y chromosome and female parent contributes 22 autosomes
and one X chromosome
Q NO 29:-Only
variations that confer an advantage to an individual organism will survive in a
population. Do you agree with this statement? Why or why not?
ANS:-We agree with the statement that Only
variations that confer an advantage to an individual organism will survive in a
population. All the variations do not have an equal chance of surviving in the
environment in which they find themselves. The chances of surviving depend on
the nature of variations. Different individual would have different kind of
advantages. A bacteria that can withstand heat will survive better in a heat
wave. Selection of variants by environmental factors forms the basis for
revolutionary process.
UNIT XV : Our Environment
TOPIC :-OUR ENVIRONMENT
Environment:- Environment is defined as the surroundings in which the
organism lives. The environment may be the physical environment, the chemical
environment or the biological environment. Thus, the environment has two
components - Abiotic and Biotic. The
Abiotic environment includes the air (atmosphere), water (hydrosphere) and land
(lithosphere). The biotic environment includes the plants, animals and the
microbes.
Organisms are
dependent on the environment to fulfil their needs; man is also constantly
interacting with the environment in order to fulfil his needs. These needs
include the basic needs of oxygen, food and shelter in addition to the social
needs like entertainment, medicines, etc. The things that man requires for his
survival and comfort are called the resources. The environment is a reservoir
of resources. Maintaining the natural resources of the environment and their
careful use is called conservation. The conservation of environment involves
the conservation of the natural resources.
A healthy environment
is an absolute necessity for the well-being of all organisms, including man.
All our needs, big and small are being met by the environment. However, man
having reached the pinnacle of evolution is trying to bring about changes in
the environment to suit his convenience. Unfortunately, this convenience is
temporary. In the long run, man is losing out on a healthy environment.
What happens when we add our waste to the environment:- Accumulation of wastes due to its improper
disposal is a major problem in our country. Population has been growing at a
rapid rate. With this increase, there has also been an increase in the amount
of wastes being produced especially in the cities. Every person, on an average
generates about 400 to 500 grams of wastes per day. At this rate, in a city of
about 10 lakh people around 500 tonnes of wastes is being produced every day.
In the absence of
proper waste management, this waste lies littered on our streets, road corners
and improperly disposed of in vacant land. All of these are serious health
hazards apart from being eyesores. If they are not cleared regularly at the
earliest, they invite host of problems like increasing numbers of insect
vectors like flies, mosquitoes, etc., scavengers such as stray dogs, pigs and
rats which spread dangerous diseases. It also generates bad odour and causes
pollution. This in turn gives rise to epidemic diseases in and around our
surroundings.
Ecosystem:- The environment in which the man and other organisms
live is called the biosphere. The biosphere is made up of different regions
that have different types of flora (plants) and fauna (animals). The types of
organisms in an area are determined by various factors such as the climate,
temperature, rainfall, etc.
An ecosystem is a
complete community of living organisms and the non-living materials of their
surroundings. Thus, its components include plants, animals, and microorganisms;
soil, rocks, and minerals; as well as surrounding water sources and the local
atmosphere. The size of ecosystems varies tremendously. An ecosystem could be
an entire rain forest, covering a geographical area larger than many nations,
or it could be a puddle or a backyard garden. Even the body of an animal could
be considered an ecosystem, since it is home to numerous microorganisms.
Components of ecosystem:- The various components of an ecosystem are
categorised into two main types. i.e. Abiotic (non living) and biotic (living)
components.
i.
Abiotic components:- These components consists of air, water,
soil, minerals and climatic conditions like light, temperature, pressure,
humidity etc. It also includes organic compounds like carbohydrates, proteins,
lipids etc. along with inorganic substances like carbon dioxide, nitrogen,
oxygen, sulphur.
ii. Biotic components:- The living organisms present in an ecosystem form the
biotic components; it includes the green plants called as producers or
autotrophs, animals called consumers (Herbivores, carnivores and omnivores) and
micro organisms (decomposers or saprotrophs).
a. Producers:- Those organisms which can synthesise their own food
through photosynthesis by using carbon dioxide, water and sunlight are called
as producers or autotrophs. e.g. green plants.
b. Consumers:- Those organisms which depend on autotrophs or producers
for their food directly or indirectly are called as consumers. These organisms
are of three types.
i.
Herbivores:- The animals which consume plants directly as their food
are known as herbivores. e.g. cow, deer goat etc.
ii. Carnivores:- The animals which consume other animals as their food
are known as carnivores. e.g. lions, tigers, snake etc.
iii. Omnivores:- The animals which
consume both plants as well as animals as their food are known as omnivores.
e.g. man, dog, cat, bear etc.
c. Decomposers (reducers or saprotrophs):- The non-green micro organisms like bacteria
fungi etc. Which depend upon dead and decaying plants animals for their food
are called as decomposers. They decompose the dead bodies of plants and animals
into simpler substances and release the essential elements into the nutrient
pool.
Importance o decomposers:- The decomposers help in decomposing the dead
bodies of plants and animals and hence act as cleansing agents of the
environment. They also help in putting back various elements of which dead
plants and animals were made into the soil, water and air which are being
reused by the producers (plants). This shows that decomposers help in recycling
off materials in the biosphere so that the process of life may go on like an
unending chain.
Food Chains:- A food chain is a series of steps by which energy is
obtained, used, and transformed by living things. For example; sunlight helps
plants to grow, the plants are eaten by cattle, and lions eat the cattle and so
on. We know that green plants manufacture their own food with the help of sun's
energy and from common elements derived from air, water and soil. These green
plants are, therefore, called the autotrophs.
The autotrophs are the chief source of potential energy for the living world.
Hence they are called the producers.
When the producers are eaten by some animal, the energy of the producers is
passed on to the animal which is called consumer.
The primary consumer is eaten by another animal which is called the secondary
consumer which may be eaten by a tertiary consumer and so on. This pathway of
energy transfer from one organism to another constitutes a food chain. For
example, in a forest community, grass is eaten by a deer which, in turn, is
eaten by a lion. This flow of energy from grass (producer) to deer (primary
consumer) and then to lion (secondary consumer) is called a food chain. The
shorter the food chain, the greater is the available energy.
A food chain always
begins with the producers, i.e., green plants. Next in the chain is always the
plant eater or the herbivore which is called the primary consumer. The primary
consumers are eaten by flesh eaters - the secondary and tertiary consumers.
Certain food chains may be very long and may extend to fourth, fifth or even
higher order consumers. In aquatic ecosystems of the biosphere, like fresh
water ponds, lakes or sea, the food chain starts with microscopic free floating
plants (phytoplankton).
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Trophic Levels:- Each link in a food chain is known as a trophic level.
For example, in each food chain, plants always form the first trophic level.
The plant eating animals called herbivores like insects, rodents, rabbits,
deer, cattle, etc. form the second trophic level. The animals like frog, small
fish, small birds which feed on the second trophic level organism form the
third trophic level. These are eaten by still longer carnivores like lion or
tiger, which constitute the fourth trophic level.
Significance of Food Chains:- The study of food chains helps in
understanding some of the important aspects of the ecosystem in particular and
environment in general.
·
The food relationship among the different organisms in an
ecosystem.
·
The food chains are the living components of the
biosphere.
·
These are the vehicles of transfer of energy from one
level to another.
·
Through the food chains, transfer of materials and
nutrients also takes place.
Food webs:- The network of food chains which become interconnected
at various trophic levels so as to form a number of feeding connections amongst
different organisms of a biotic community is called as a food web.
Characteristics of food webs:-
i.
Food webs are never straight like food chains. It is
formed by the interlinking of various food chains.
ii.
It provides the alternative pathways of food availability
for different organisms with respect to their food habits.
iii.
Greater alternatives available in a food web make the
ecosystem more stable.
iv.
Food webs also help in checking the overpopulations of
highly productive species of plants and animals.
v.
Food webs also help in ecosystem development.
Energy Flow:- All living beings require a constant supply of energy for
the various functions they perform. The energy is obtained from the sun. This
energy is introduced into the biosphere by green plants by a process known as
photosynthesis. Plants are able to trap this light energy and by the process of
photosynthesis convert it into chemical energy. Thus the initial point of entry
of energy in the ecosystem is through the green plants (autotrophs or
producers). It has been estimated that on an average, about one per cent of
total sun's energy reaching the earth is trapped by green plants during the
process of food manufacture (i.e., photosynthesis). The energy thus trapped by
plants is stored as carbohydrates. Some of the energy trapped by plants is used
by them in performing their metabolic activities like respiration, growth,
etc., and some energy is released in the atmosphere as heat. When the plants
are eaten by herbivorous animals, the energy stored in plants gets transferred
to the consumer animals. These animals utilize this energy for their own
metabolic activities. Here again some of the energy is released as heat. When
primary consumers are eaten by secondary consumers, the same process is
repeated at every step of the food chain. Here it must be remembered, that
energy released as heat is considered as energy lost.
So we can conclude that
·
Conversion of energy takes place from one form to
another. The light energy gets converted into chemical energy by plants during
photosynthesis.
·
Plants act as converters of energy. They do not produce
energy.
·
The energy lost as heat is quite substantial, if taken
together from various trophic levels
·
During the transfer of energy through successive trophic
levels in an ecosystem, there is a lost of energy at each trophic level. In
other words, the level following the previous one always receives less amount
of energy.
·
The flow of energy is unidirectional. It enters into the
living system from non-living environment
The energy lost at heat cannot be utilised
The 10 per cent law of flow of energy:- It
states that about 90% of the energy is used up at each level and only 10% of it
is transferred to the next trophic level. As a result, at the last trophic
level (decomposer), no energy is left for recycling. This is how the flow of
energy is unidirectional. Fast decreasing energy level at each step sets the
limit of trophic levels only to 4-5 at the maximum. Therefore, the plants
(producers) receive the maximum energy and as you go further down the trophic
levels, the energy in the food goes on decreasing.
Impact of Man's Activities on Environment:- Human beings are the integral
part of the environment and the human activities make changes in the
environment which in turn affect the human beings in various aspects.
Environment is affected by the human activities in a number of ways but
depletion of ozone layer and the waste disposal are the two main problems which
influenced the whole living community.
Depletion of Ozone layer:- Ozone is a form of oxygen gas. Ozone (O3) is a molecule formed
by three atoms of oxygen while oxygen (O2), is essential for all
aerobic forms of life. Ozone is a deadly poison. However, at the higher levels
of the atmosphere, ozone performs an essential function. It shields the surface
of the earth from ultraviolet (UV) radiation from the Sun. UV radiation causes
skin cancer, damage to eyes, immune system. It can also affect global rainfall
and cause ecological disturbances.
Ozone at the higher levels of the atmosphere is a product of UV radiation
acting on oxygen (O2) molecule. The higher energy UV radiations
split apart some molecular oxygen (O2) into free oxygen (O) atoms.
These atoms then combine with the molecular oxygen to form ozone as shown in
the equations below.
The thinning of
ozone layer is commonly known as ozone depletion. It is being depleted by air
pollutants and the synthetic chemicals like chlorofluorocarbons (CFCs) which
are used as refrigerants and in fire extinguishers. Besides this methane and
oxides of nitrogen depletes ozone layer. The Declining in thickness of ozone layer
over a restricted area is called as ozone hole. Ozone hole was first discovered
over Antarctica in 1985.
Waste Management:- We are an integral part of the environment. Our
activities change the environment around us. Changes in the environment affect
us. Environmental problems like depletion of the ozone layer and waste disposal
are issues that have to be dealt with serious concern. In our daily activities,
we generate a lot of materials that are thrown away. These accumulated wastes
can be classified as biodegradable and non-biodegradable. Substances that are
broken down by biological processes are said to be biodegradable. Substances
that are not broken down by biological processes are said to be
non-biodegradable.
The huge amount of
municipal refuse generated daily demands a highly efficient system to manage
its collection and disposal. Waste management has been a serious issue in urban
areas. Disposing garbage at the outskirts of a city is a common sight. Empty
cans, food wrappers etc. which are non-biodegradable are littered in crowded
places and tourist centres. It is necessary to have awareness regarding methods
of disposing different types of waste.
Improvements in our
life-style have resulted in greater amounts of waste material generation. Changes
in attitude also have a role to play, with more and more things we use becoming
disposable. Changes in packaging have resulted in much of our waste becoming
non-biodegradable.
The disposal of the waste we generate
is causing serious environmental problems. There are a number of concepts about
waste management, which vary in their usage between countries or
regions. The waste hierarchy refers to the
"3 Rs" reduce, reuse and recycle, which classify waste management
strategies according to their desirability in terms of waste minimization.
Biological Magnification:- Extensive usage of
several pesticides and other chemicals to protect our crops from diseases and
pests has resulted in the entry of these harmful chemicals into our bodies through
the food chain. These chemicals are either washed down into the soil or into
the water bodies. From the soil, these are absorbed by the plants along with
water and minerals, and from the water bodies these are taken up by aquatic
plants and animals. This is one of the ways in which they enter the food chain.
As these chemicals are not degradable, they get accumulated progressively at
each trophic level. As human beings occupy the top level in any food chain, the
maximum concentration of these chemicals gets accumulated in our bodies. This
phenomenon is known as biological magnification. This is the reason why our
food grains such as wheat and rice, vegetables and fruits, and even meat,
contain varying amounts of pesticide residues. They cannot always be removed by
washing or other means.
TEXTUAL QUESTIONS
Q NO 1:-Why are some substances biodegradable and some
non-biodegradable?
Ans:-Substances which are of organic origin
are biodegradable, while those of inorganic origin are non-biodegradable.
Organic substances can be utilized by decomposers as food, while other
substances cannot be utilized by decomposers as food. Due to this, some
substances are biodegradable while some others are non-biodegradable.
Q NO 2:-Give any two ways in which biodegradable substances
would affect the environment.
ANS:-Biodegradable substances can affect the
environment in following ways:
a) By recycling the raw materials in nature.
b) By improving the humus content in soil.
Q NO 3:-Give any two ways in which non-biodegradable
substances would affect the environment.
ANS:-Non-biodegradable substances would affect the environment in
following two ways:
- By
increasing the burden on the environment because they would accumulate.
- By
producing harmful polluting gases, if they are burnt.
Q NO 4:-What are trophic levels? Give an example of a
food chain and state the different trophic levels in it.
ANS:-A
particular level in a food chain is called trophic level. Following example
shows trophic levels in a food chain:
Producer → Primary Consumer → Secondary
Consumer → Tertiary Consumer
Grass → Grasshopper → Frog → Snake
Q NO 5:-What is the role of decomposers in the
ecosystem?
ANS:-Decomposers decompose dead remains of plants
and animals. By doing so, they serve two purposes. One; they reduce the burden
on the environment by clearing dead remains. Two; they channelize the raw
materials back to the environment.
Q NO 6:- What is ozone and how does it affect any
ecosystem?
ANS:-Ozone is a form of oxygen. Ozone is a
triatomic molecule while oxygen is a diatomic molecule. Ozone forms the ozone
layer in our atmosphere. Ozone plays an important role in the ecosystem. The
ozone layer wards off harmful ultraviolet radiations from the sun and thus
protects the living beings.
Q NO 7:- How can you help in reducing the
problem of waste disposal? Give any two methods.
ANS:-The problem of waste disposal can be
reduced in many ways. Two methods are given below:
- By
using more of biodegradable substances and reducing the use of
non-biodegradable substances. For example; instead of plastic bags, one
should carry jute bags or cloth bags for shopping.
- By
proper segregation of waste before disposing.
Q NO 8:-Which of the following groups contain
only biodegradable items?
- Grass, flowers and leather
- Grass,
wood and plastic
- Fruit-peels,
cake and lime-juice
d. Cake, wood and grass
ANS:-
Both c & d.
Q NO 9:-Which of the following constitute a
food-chain?
- Grass, wheat and mango
- Grass, goat and human
- Goat, cow and elephant
d. Grass, fish and goat
ANS:- (b) Grass, goat and
human
Q NO
10:-Which of the following are environment-friendly practices?
- Carrying cloth-bags to put
purchases in while shopping
- Switching off unnecessary lights
and fans
- Walking to school instead of
getting your mother to drop you on her scooter
d. All of the above
ANS:- All of the above
Q NO 11:-What will happen if we
kill all the organisms in one trophic level?
ANS:-If all the organisms in one trophic level are killed, it will disturb
the whole ecosystem. Let us take a hypothetical example to understand this. If
all the deer are killed in a jungle, the lions would be left with no food. This
would endanger the existence of lions. Once the lions and deer would be
finished, it would result in population explosion of green plants. If all the
lions die in a jungle, it would create another problem. Since no lion would be
left to kill the deer, the population of deer would increase substantially. This
will finish off all the green plants and finally even the deer would be left
with no food for them.
Q NO 12:-Will the impact of
removing all the organisms in a trophic level be different for different
trophic levels? Can the organisms of any trophic level be removed without
causing any damage to the ecosystem?
ANS:-The impact of removing all the organisms in a
trophic level shall be similar for different trophic levels; although their
manifestations can be different. Organisms of any trophic level cannot be
removed without causing any damage to the ecosystem. The examples of lions and
deer in the previous answer illustrate this.
Q NO 13:-What is biological
magnification? Will the levels of this magnification be different at different
levels of the ecosystem?
ANS:-The accumulation of a particular substance through
different trophic levels is called biological magnification. Let us take
example of lead poisoning which may affect plants because of water pollution.
The level of lead would be at a particular level in plants. When an herbivore
would eat these plants, the level of lead shall be more in the body of
herbivore because it would eat a large number of plants. When this herbivore
would be eaten by a carnivore, the level shall rise further because the
carnivore would eat a large number of herbivores. Hence, the level of this
magnification will increase as we move to higher trophic levels.
Q NO 14:-What are the problems
caused by the non-biodegradable wastes that we generate?
ANS:- Non-biodegradable waste creates many problems. Biodegradable waste
keeps on accumulating in the environment because it does not decompose.
Hypothetically, a time may come when the whole earth would be filled with
non-biodegradable waste. If we try to destroy such waste by way of burning, it
would create many polluting gases.
Q NO 15:-If all the
waste we generate is biodegradable, will this have no impact on the
environment?
ANS:- If all the waste we generate is biodegradable,
this would also have an impact on the environment but most of the impacts would
be positive. After decomposition, the biodegradable substance produces
different raw materials which are sent back to the ecosystem. The solid remains
would add to the humus content of soil.
There can be some negative impacts;
like obnoxious smell which is created during the process of decomposition.
There can also be a possibility of sparking an epidemic if the waste is dumped
near a residential area or is allowed to contaminate the water bodies. So, it
is not the biodegradable waste which is going to create the problem, rather the
way we dispose it.
Q NO 16:-Why is damage to the
ozone layer a cause for concern? What steps are being taken to limit this
damage?
ANS:-Ozone layer works like a protective shield for
living beings. The ozone layers wards off harmful ultraviolet radiations from
the sun. Damage to the ozone layer can result in increased level of ultraviolet
radiations in our atmosphere. This would be very dangerous for all life forms.
In 1987, the UNEP (United Nations Environment Programme) succeeded in
forging an agreement among different nations to freeze the CFC production at
1986 level. Later, an agreement was signed among different nations to phase out
CFCs. It is important to note that CFC is used in refrigerators and aerosol
spray. India is also a signatory of that agreement and thanks to the efforts by
the United Nations and different environmentalists, the CFC emission has been
put under some control.
UNIT XVI : Management of Natural Resources
TOPIC:- MANAGEMENT OF 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.
Conservation of natural resources (why do we
need to manage our resources):- Conservation is defined as the controlled utilization
of natural resources for the benefits of all life so that it may yield
sustainable benefit to the present generation as well as the future generation.
It is the sustainable use of natural resources, such as soils, water, plants,
animals, and minerals. With
the enormous increase in human population and advancement in technology, the
natural resources are being over exploited, without caring for the resultant
consequences. If the natural resources are not managed then the future
generation have to suffer with its consequences of not having them at all.
In
economic terms, the natural resources of any area constitute its basic capital,
and wasteful use of those resources constitutes an economic loss. From the
aesthetic and moral viewpoint, conservation also includes the maintenance of
national parks, wilderness areas, historic sites, and wildlife. In certain
cases, conservation may imply the protection of a natural environment from any
human economic activity. While conservation and utilization of
natural resources in a sustainable manner are what responsible citizens and the
governments should aim to achieve, it might be useful to assess how we as
students and youth can immediately contribute to helping out at our own level.
To ensure sustainable use of resources in our environment utilize the principle
of 'The Three R's.' - Reduce, Reuse, and Recycle.
i.
Reduce:- Use less and do not waste. Resources
saved are resources earned for your community. Do not waste water - switch of
running and leaky taps, bathe with a bucket don't shower; Don't waste energy -
turn out the lights and fans when you are not in a room, take public transport
or walk short distances instead of using expensive motor fuel. Don't waste
food. Give unused food to less fortunate or animals.
ii.
Reuse:- Use things again and again. Don't
throw away materials such as glass containers, plastic bags, paper, cloth etc.
Reuse them at domestic levels rather than being thrown. It reduces solid waste
pollution.
iii. Recycle and Recovery:- Materials such as paper, some kinds of
plastics and glass can are being recycled. Collect plastic, paper, glass and
metal items and give them to people who recycle these materials. This decreases
the volume of refuse and helps in the conservation of natural resources. A
recovery of one tone of paper can save 17 trees.
iv. Reforest:- Plant a tree during the rains. Look
after it for a couple of years. Make your environment more cool, shady and
green. Let the birds, squirrels, butterflies and animals dependant on trees
return to their habitat; simultaneously, help control soil erosion.
Forests and
wild life:- The biotic component of our
environment on land, i.e. plants and animals (leaving aside the oceans and
other water bodies) are overwhelmingly found in forests. Forests form a buffer
for the earth to protect life forms; in fact that's where all our biodiversity
and including cultivated crops and horticulture plants and trees originated
from. Forests comprise an area of diverse and complex ecosystems consisting
mainly of trees, shrubs and wild plants which house an extraordinary variety of
communities of living organisms. The Indian forests for example include variety
of plant and animal life. India has over 45,000 plant species and its forests
have about 800 species of mammals, 2000 species of birds, 420 species of
reptiles, 2000 species of fish, 50,000 species of insects, 4000 species of
molluscus. Good forest areas therefore are called the 'biodiversity hot spots'
due to the wide range of life forms and genetic diversity of life forms. One of
the main aims of conservation is to try and preserve the inherited
biodiversity. A loss of diversity will lead to an ecological imbalance. There
is a clear and mutual relation between the health of forests (trees), rainfall
concentration, the amount of water in rivers and conservation of wild animals.
Stakeholders:- Humans depend on the forests largely
to meet rapidly growing demands for timber, fibre, fuel, fresh water and food.
All use forest produce in one form or other, e.g., when used as timber, paper,
herbs and spices. Modern approaches in forest conservation have found that
enforcement of forest laws or policies that do not recognize the legitimate
needs of different groups that depend on the forest, often fail in their
objectives. When we consider the conservation of forests, we need to look at
different stakeholders whose dependency on forest resources varies.
i.
People who live in or around forests are dependent on forest
produce for various aspects of their life.
ii.
The Forest Department of the Government which owns the land
undertakes protection and controls the resources from forests
iii.
The industries that use various forests produce, but are not
dependent on the forests in any one area
iv.
Environment Conservationists, nature enthusiasts and NGOs who want
to conserve nature in its immaculate form
The practice of clearing huge areas to plant pine, teak or
eucalyptus, results in destroying a large amount of biodiversity. It also
adversely affects the stakes and needs of local people living in and around
such forest plantations by loss of habitat and inaccessibility to these areas.
They experience a scarcity of supplies of wood and fodder, herbs, fruit and
nuts etc. The loss of valuable habitat and ecosystems is probably largest for
flora and fauna living in the area.
Deforestation:- The destruction, reduction or removal
of forest cover is known as deforestation. It may lead to the destruction of
biotic potential of land or desert formation. The main reasons of the
deforestation are
i.
The
indiscriminate felling of trees for the purpose of timber, fuel and industrial
demand of wood.
ii.
Overgrazing by
a large livestock population.
iii.
Shifting
cultivation for agriculture.
iv.
Construction
of dams, reservoirs, canals, hydroelectric projects, roads and railways.
v.
Forest fires
which can be natural or manmade.
Effects of deforestation:- The various effects of the deforestation are
i.
Large scale
deforestation has badly affected the weather of the surrounding places.
ii.
It has lead to
the scarcity of timber wood, fuel wood and the wood used in industries.
iii.
It has lead to
soil erosion, droughts, floods and landslides.
iv.
Deforestation
by overgrazing has reduced the regenerative capacity of the forests.
Forest
conservation:- The
conservation of forests is development, management and full protection of
existing forest cover so as to provide optimum sustainable yield. The various
measures to be taken for the forest conservation are
i.
Afforestation:- plantation of
indigenous or exotic species to develop forests in all the available land is
known as Afforestation. Afforestation prevents denudation of natural forests.
ii.
Conservation of reserve forests:- Many areas of natural forests are protected from fuel
starved villagers, fodder starved cattle and commercial exploitations. These
reserved forests include national parks, sacred grooves, bio reserves etc. such
forests are not allowed to be disturbed.
iii.
Social forestry: It is a kind
of Afforestation where groups of people raise quick growing multipurpose trees
and shrubs on village common land, vacant lands, road sides etc.
iv.
Agro forestry: It is a kind
of Afforestation where multipurpose trees, shrubs, horticultural plants and
forage plants are grown in fields along with crops. It fulfils the requirement
of fodder, fruits, flowers, fuel wood and timber. It reduces the pressure on
real forests.
v.
Urban forestry: Plantation of
multipurpose trees, shrubs and flower/fruit bearing plants in open lands of
urban area is called as urban forestry. It helps to check air pollution and
reduce noise pollution, besides providing fuel wood, timber, vegetables, fruits
and many other products.
Wild life:- All the
naturally occurring animals, birds, plants and other life forms in the forests
which are neither domesticated nor tamed are collectively called as wild life.
Wild life is necessary in maintaining the ecological balance.
Importance of wildlife:-
i.
Wildlife
maintains an ecological balance of nature.
ii.
It provides a
great biological diversity (occurrence of a large number of species in an
area).
iii.
It serves as a
source for domestication of animals and cultivation of crop plants.
iv.
Wild life
provides many valuable products like life saving drugs, silk, lac, honey,
feathers, musk, ivory, fine decorative leather etc.
Wildlife
conservation: Conservation of wild life is the management of wild
flora and fauna in order to save them from their extinction as well as to get
sustainable benefit for both present and the future. Some of the ways for the
wildlife conservation are
i.
Protection of natural habitats: Natural habitats of wild life must be protected by
identification and safeguard of feeding, breeding and nursing of each species.
ii.
Maintenance of wildlife in protected areas: The wild
animals are allowed to grow in number in natural habitats in protected areas
through preventing pouching, maintaining habitats and their requirements, an
all these steps are possible in
biosphere reserves, national parks and wildlife sanctuaries.
iii.
Protection through legislation: Wildlife can
also be protected by the implementation of a number of wildlife protection acts
being formulated by the government in order to protect wildlife from being
hunted and the unauthorised killing and import-export of wildlife products.
Sustainable Management: India has about 63.5% million hectares
of forests and forms 1/5th of the geographical area of the country.
For any one stake holder namely the forest department, to safeguard the forests
and its flora and fauna along with the sustainable harvest of forest produce by
solely its own effort is extremely difficult. It is now recognized as a
participative effort of the stake holders involved in a particular area. While
the government, and conservation enthusiasts and organizations have a major
role in overseeing the protection and conservation of forests, the acceptances
of the dependencies of local players who have lived in harmony with natural
resources is vital for success of forest conservation measures. One
needs to consider if the goals of all the above stakeholders with regard to the
management of the forests. The stakes of local players, such as fuel and
fodder, the right to stay, must be met if management of wildlife and forests
has to be successful.
Water for All:- Water is a unique and remarkable compound, essential to all forms
of life. Human beings and the flora and fauna cannot survive without water on
this planet. A large amount of life on this planet is aquatic based i.e., can
only survive in water. It is the most abundant substance after air in the
earth's biosphere. Oceans,
seas and other saline inland water bodies, make 97.3% of the total global
supply of water which is not available for human consumption due to high salt
content. Fresh water accounts for only 2.7% of the total estimated global water
supply! Of this percentage, 75% of the fresh water is frozen in polar ice caps
and the glaciers, like those in the Himalayas. Some fresh water is blocked in
inaccessible areas under the ground. The fraction of fresh water available for
humans is estimated at less than 0.003% of the total global water availability!
Even though water is a renewable source, the evident conservation of water and
non-pollution of freshwater sources is a must, given its vital importance both
biologically and chemically and continuing global population explosion.
Of the fresh water available
there are three main sources. The first one is rainwater (or precipitation).
The second source is surface water; which includes rivers, lakes, ponds,
canals, streams etc. The third is ground water or underground aquifers which is
the water that percolates down the surface soil into pore spaces of rocks. The
total volume of ground water found in the aquifer is estimated to be 42.3 x 1010
m3. Ground water provides soil moisture for plants and
supplements for streams and lakes. It is a reserve supply of water that the
agricultural sector and urban water supply sectors are tapping increasingly.
The water table indicates the level at which ground water is found, and rises
and falls according to the level water that percolates down to this level
during the rains and the amount that is pulled out from it.
Dams: Dams are the
large water storing bodies usually built by the government agencies across the
rivers to regulate the flow of water. They store water enormous amount of water
sufficient for irrigation of fields throughout the year. The stored water is
then allowed to flow downstream in order to generate hydroelectricity and carry
the water long distances for the purpose of irrigation. Thus, dams not only help in the irrigation of
agricultural fields but also employed for generation of electricity.
Besides the various benefits from the large dams there are certain problems
associated with the construction of these dams and are categorised in the
following categories.
i.
Social problems: The dams submerge forever the
traditional living areas and cause loss of traditional sources of livelihood. A
large number of villagers and tribals who have been displaced by various
development projects are largely poor. They do not get any benefits from these
projects and are alienated from their lands and forests without adequate
compensation or proper rehabilitation.
ii.
Economic problems: Huge amounts of public money are spent
on Dams. Critics feel that the net benefits to the people and society are not
proportionate and lopsided favouring urban industrial and government
priorities, generation of power and irrigation at the expense of local people
in the dam belt area.
iii.
Environmental problems: Dams
contribute enormously to deforestation and the loss of biological diversity.
They can also result in potentially huge accidents during disasters like
earthquakes. The politicization and mismanagement of water supply biased
towards selected few, due to lack of equitable distribution of water people
close to the source of dam irrigation grow water intensive crops like sugarcane
and rice while people farther downstream do not get any water. Secondly, loss
of local control on water resources and loss of local decentralized methods of
irrigation which were judicious and much closer to the ground in terms of
identifying water needs and tailoring optimal solutions. Large water dams can
destroy the flora and fauna of the area which get submerged.
Advantages
and disadvantages of dams:
Advantages
i.
Dams benefit people by providing usable, reliable water sources.
ii.
They improved the quality of life by providing drinking water.
iii.
They support the economic growth by diverting water for power,
navigation, flood control, and irrigation.
iv.
In many parts of the world dams have helped to remedy
life-threatening problems such as famine as a result of drought, devastation
from floods, and continued disease from lack of potable water supplies.
Disadvantages
i.
Disruption of ecosystems by submerging of vast catchment areas.
ii.
Decline of fish stocks.
iii.
Forced resettlements.
iv.
Dams change the chemical, physical, and biological processes of
river ecosystems.
v.
They alter free-flowing systems by reducing river levels, blocking
the flow of nutrients, changing water temperature and oxygen levels, and
impeding or preventing fish and wildlife migration.
Water
Harvesting: Almost 90% of the rainwater in India is running off every monsoon
and only 10% of the rainwater is utilized (collected and stored). Rainwater
harvesting is the process of collection and storage of rainwater with the
purpose of consuming it or using it to recharge ground water. The conservation
of water by harvesting is in order to increase the biomass production. Its main
aim is to develop primary resources of land and water and to produce secondary
resources of plants and animals in a manner which will not cause ecological
imbalance.
Rain Water Harvesting: Rainwater harvesting can be surface
runoff harvesting that collects the rainwater runoff from paved and unpaved
surfaces in village or town and is directed into open tanks or wells; low yield
bore wells and percolation pits to recharge subsurface aquifers. Measures to
keep that water clean by not allowing polluting activities to take place in the
catchments should also be ensured. It can also be Rooftop Harvesting where
rainwater is collected from rooftops, filtered, stored in tanks and then used
for all appropriate purposes usually domestic.
The aim of Rainwater harvesting is to:
Regenerate the primary resources of land and water sources.
Help produce
secondary resources for plants and animals to avoid any ecological imbalance.
Most water harvesting techniques are highly specific to an area and the
benefits are also localized. In many degraded areas in the plains water
harvesting has semi-circular shaped earthen embankments or low, straight
concrete and rubble "check dams" built across seasonally flooded
gullies. Monsoon rains fill ponds behind dwelling structures. Some of these
large earthen embankments or low "check dams" can store water from up
six months till a full year until the monsoons arrives again.
Coal
and Petroleum:
Coal: Fossil fuels, like, coal, lignite,
petroleum and natural gas are non renewable natural resources. Both have an
organic origin and are called hydrocarbon fuels. Coal was formed in nature as a
solid from the remains of the trees buried deep inside the earth, some 500
million years ago. The more heat and pressure coal undergoes through, the
richer becomes the carbon content of it.
Petroleum: Petroleum also occurs deep inside the
earth's crust, as a liquid, and is formed by the bacterial decomposition of
marine plant and animal matter and prehistoric forests in the absence of air
buried at the bottom of the seas. This decomposition takes place under high
pressures and temperatures of about 200oC, with the passage of
millions of years of time.
Utility of Coal and Petroleum: The use of coal and petroleum and
their products in the world economy is immense. Coal is an important fuel
source as its energy is converted into other forms of energy such as
electricity, steam and coal gas. Many thermal power stations are run on coal.
Coal is used for many industrial applications such as fuel for iron and steel
foundries, metal extraction plants and steam based turbines. Coal tar, a black
liquid, produces a mixture of over 200 carbon compounds which are used to
prepare drugs, dyes, paints, explosives, plastics etc. It is a source of
aromatic hydrocarbon compounds like benzene, toluene, aniline, phenol,
naphthalene, anthracite etc. Coke is an important reducing agent is another
by-product containing 98% carbon. Petroleum
is often referred to as liquid gold, due to its importance as a fuel in
transportation (Petrol, Diesel, kerosene, gas oil, fuel oil) and as a source of
over hundred and fifty important petrochemicals used in industrial and consumer
applications. Over 25% of the entire chemical industry is devoted to the
extraction of petroleum to get petrochemicals. The prosperity of any country
depends upon these petroleum reserves.
Management of coal and petroleum: The management of such non renewable
energy sources involves slightly different perspectives from the other
resources. One way of conservation and managing of these resources is to
substitute existing technologies so that hydrocarbon fuels are more efficiently
used or used less. For example, the use of vehicles with more efficient mileage
and exhaust characteristics or a substitution of fuel or raw material. Some
technologies in cars now use alternate fuels in combination with petrol
(alcohol mixed petroleum) or completely use Bio fuel. Biogas can replace Liquid
petroleum fuel (LPG) for cooking in rural areas. A second route is to affect
the policy of finding non-conventional and renewable energy sources. Power
generation technologies are being developed by using wind energy through
windmills, hydro energy and nuclear energy for generating electricity. Steam
turbines are used in industries and solar energy based technologies (solar
voltaic cells, solar panels are being used for areas such as for lighting, communications,
solar heating etc. to reduce the dependence on hydrocarbon fuels.
An Overview of Natural Resource
Management: Our natural resources are our assets whose prudent and
sustainable use is necessary for the well being of humans and other living other
organisms. Unfortunately, the continuous and ever increasing demand for basic
items of survival and technological developments have caused us to explore and
exploit all possible natural resources. As individuals we tend to consume
resources without giving a thought to conservation or harmful impact of over
use or careless consumption. Other stake holders like industry are also driven
by short term gains. Governments across the globe have been slow to react to
the risks of various stake holders and have learnt the hard way that we are
dangerously coming to a point where over exploitation and mismanagement is
leading to global energy crisis and global warming. Governments, individuals and other stake holders are now
realizing the issues involved and need to act sensibly to maintain a balance
between environment and development. No doubt sustainable management of natural
resources at all levels is a difficult task. We still have to adjust our
requirements, individually and collectively so that the benefits of management
and conservation reach the widest cross section of society and meet the future
generations.
TEXTUAL QUESTIONS
Q NO 1:- What changes can you make
in your habits to become more environment friendly?
ANS:-We can be eco-friendly by following these simple rules:
(a) By using the principle of 3R's i.e. Reduce, Reuse and Recycle.
(b) By putting off unnecessary lights and fans.
(c) By using unleaded petrol in vehicles.
(d) By using local transport like buses or train.
Q NO 2:-What would be the
advantages of exploiting resources with short-term aims?
ANS:-If resources are exploited with short-term
aims it will be very beneficial for the present generation as it will help in
growth of economy at a faster rate.
But it will deprive future generations from the
benefits of these resources as they are exhaustible.
Q NO 3:-How would these advantages
differ from the advantages of using a long-term perspective in managing our
resources?
ANS:-If resources are used in accordance with short term aims,
present generation will be able to utilize the resources properly for growth
and development.
But, if we use resources with long term aims, future generation will also be
able to utilize resources for fulfilling its needs.
Thus, it would be better to use our natural resources with a long term
perspective so that it could be used by the present generation as well as
conserved for future use.
Q NO 4:- Why do you think
there should be equitable distribution of resources? What forces would be
working against an equitable distribution of our resources?
ANS:-There should be equitable distribution of resources so that
all countries would be able to fulfill their needs and grow properly.
Forces working against equitable distribution of resources are:
i. Land form.
ii. Climate
iii. Distribution of rainfall.
iv. Type of soil.
Q NO 5:-Why should we conserve forests
and wildlife?
ANS:-It is necessary to conserve forests and wildlife as it
conserves the biodiversity which we have inherited.
Q NO 6:-Suggest some approaches
towards the conservation of forests.
ANS:-Following
measures are taken to conserve forests:
i.
Conversion of forests into national parks, sanctuaries.
ii. To take help from local people in conserving forests.
iii. We should not allow the destruction of forests for making roads, dams and
hotels etc.
iv. Planting more trees.
Q NO
7:-Find out about the traditional systems of water harvesting/management in
your region.
ANS:-The traditional systems of
water harvesting used in our region are tanks, wells and tube wells.
Q NO
8:-Compare the above system with the probable systems in hilly/mountainous
areas or plains or plateau regions?
ANS:-In plains, the water
harvesting structures are crescent-shaped earthen embankments. These are low,
straight, and concrete.
In hilly regions, the system of canal irrigation called Kulhs is used for water
harvesting. This involves a collection of rain water in a stream, which is then
diverted into man- made channels down the hill sides.
Q NO
9:-Find out the source of water in your region/locality. Is water from this
source available to all people living in that area?
ANS:-The source of water in our
region is ground water. It is available to all the people living in that
area.
Water is also supplied in our area by the Municipal Corporation.
Q NO 11:- What changes would you
suggest in your home in order to be environment-friendly?
ANS:- I will suggest following changes in my home:
(a).Replace all the bulbs and tube-lights with LED (Light Emitting
Diode), to save electricity.
(b).Using natural ventilation; instead of air conditioners
to cool the rooms. (c).Using natural light
during daytime to save on electricity. (d).Use
of hand pumps, instead of electric motors to lift water.
Q NO 12:-Can you suggest some changes in your school which would make it
environment-friendly?
ANS:- I will suggest
following changes in my school:
- All the leaking taps should be immediately repaired.
- Windows of classrooms should be made bigger to allow natural
light inside the rooms.
- Blackboard should be used more often and the use of
projectors and computers should be minimized.
- Teachers should encourage students to use bicycles while
coming to school.
- Teachers should also begin using bicycles; instead of cars
and two-wheelers.
Q NO 13:-We saw in this chapter
that there are four main stakeholders when it comes to forests and wildlife.
Which among these should have the authority to decide the management of forest
produce? Why do you think so?
ANS:-The forest dwellers should have the authority to decide the
management of forest produces. There are various reasons for this. Some of them
are discussed here. Forest dwellers have traditionally been dependent on
forests for their livelihood. They have learnt to respect the forest and always
desist from overexploitation of resources. They have some traditional knowledge
which can really help in forest conservation.
Q NO 14:- How can you as an individual contribute or make a
difference to the management of (a) forests and wildlife, (b) water resources
and (c) coal and petroleum?
ANS:- (a).For forests
and wildlife:- I can contribute by reducing the use of
paper. This would help in
minimizing the need for cutting down trees.
(b).For water resources:- I can
contribute by preventing the wastage of water as and when possible.
(c).For coal and petroleum:- I can
contribute by using my bicycle for going to school. I can also take out
awareness campaigns to educate people about the benefits of using
environment-friendly modes of transport.
Q NO 15:- What can you as an individual do to reduce your consumption
of the various natural resources?
ANS:- I can do following
to reduce my consumption of various natural resources:
- I will prefer walking and cycling while commuting to short
distances.
- I will avoid wastage of water as much as possible.
- I will minimize my usage of electricity.
- I will use public transport; instead of private transport.
Q NO 16:- List five things you have done over the last one week to
(a).Conserve
our natural resources.
ANS:- For conserving our
natural resources, the five things which I did in the last one week:
o I
used bicycle for going to school.
o I
took bucket bath and stopped using the shower.
o
I used old envelopes for doing rough work during my
homework.
o
I reduced my timing for watching TV.
o
I took a public transport bus while going to a
relative’s place.
(b).Increase the pressure on our
natural resources.
ANS:- Five things which increase pressure on natural resources:
- I played video games for a long period on one day.
- I forgot to switch off the light of my bedroom and slept.
- I went to a water-park, where too much water was being
wasted.
- I threw away some plastic bottles which could have been
reused.
- I made paper planes and played with them.
Q NO 17:- On the basis of the issues raised in this chapter, what
changes would you incorporate in your life-style in a move towards a
sustainable use of our resources?
ANS:- I would make
following changes in my life style to ensure sustainable use of our resources:
- I will use bicycle more often than earlier.
- I will use fresh water for bathing in the winter season; than
using the geyser.
- I will start using jute/cloth bag, while shopping.
- I will collect old newspaper and give them to kabaadi waala;
for recycling.
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