Life Process (Nutrition) - NCERT Solutions, Class 10, Science Class 10 Notes | EduRev

Class 10 : Life Process (Nutrition) - NCERT Solutions, Class 10, Science Class 10 Notes | EduRev

 Page 1


Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009 0
WHAT IS LIFE PROCESS ?
All the living organisms including human beings perform a number of activities such as nutrition, respiration,
excretion, growth and reproduction. These activities are characteristics of living organisms, and through such
activities they maintain their lives. These maintenance function of living organisms are known as life processes.
Chemical reactions which take place within cells or organisms during various vital activities are called
biochemical reactions.
Metabolism is a word used to describe the sum total of all the chemical and physical changes that are
constantly taking place in living matter and are necessary for life. The word metabolite refers to a substance
which undergoes various changes during metabolism. For example, carbon dioxide and water are metabolites
used in the process of photosynthesis.
The metabolic pathways are of two types :
( i ) Anabolic pathways or biosynthetic pathways in which biosynthesis of organic compounds occurs,
or in other words, complex substances are synthesized from simpler ones ; for example photosynthesis.
( i i ) Catabolic pathways in which the breakdown of complex organic substances into simpler ones occurs (as
in respiration)
In anabolic pathways or processes of anabolism energy is used (endothermic reactions), while in catabolic
pathways or catabolism, energy is released (exothermic reactions).
Criteria to define something is alive :-
1. Nutrition :- The processes by which the organisms obtain and utilise the nutrients (food).
2. Respiration :- The process that involves breakdown of respiratory substrates through oxidation and release
of usable energy.
3. Transport :- The process in which the substances absorbed or synthesized in one part of the body are carried
to other parts of the body.
4. Excretion :- The process involved in removal of the excess or toxic wastes from the body.
5. Control and coordination :- The process which helps the living organisms to receive information from the
surroundings and behave accordingly in order to survive in the changing environment around them.
6. Growth and development :- Permanent increase in the size of the organisms is called growth. The whole
series of changes which an organism goes through during its life cycle, is called development.
7. Movement and Locomotion
DEFINITION :- The basic functions performed by living beings to sustain themselves are called life processes.
NUTRITION
Nutrients are inorganic as well as organic substances which the organisms obtain from their surroundings in order
to synthesize their body constituents and use them as a source of energy.
The process of intake of nutrients and its utilization by an organism in various biological activities.
O R
A process to transfer a source of energy from outside the body of the organism (food), to the inside is called
nutrition.
LIFE PROCESS - NUTRITION
LIFE PROCESS - NUTRITION
Page 2


Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009 0
WHAT IS LIFE PROCESS ?
All the living organisms including human beings perform a number of activities such as nutrition, respiration,
excretion, growth and reproduction. These activities are characteristics of living organisms, and through such
activities they maintain their lives. These maintenance function of living organisms are known as life processes.
Chemical reactions which take place within cells or organisms during various vital activities are called
biochemical reactions.
Metabolism is a word used to describe the sum total of all the chemical and physical changes that are
constantly taking place in living matter and are necessary for life. The word metabolite refers to a substance
which undergoes various changes during metabolism. For example, carbon dioxide and water are metabolites
used in the process of photosynthesis.
The metabolic pathways are of two types :
( i ) Anabolic pathways or biosynthetic pathways in which biosynthesis of organic compounds occurs,
or in other words, complex substances are synthesized from simpler ones ; for example photosynthesis.
( i i ) Catabolic pathways in which the breakdown of complex organic substances into simpler ones occurs (as
in respiration)
In anabolic pathways or processes of anabolism energy is used (endothermic reactions), while in catabolic
pathways or catabolism, energy is released (exothermic reactions).
Criteria to define something is alive :-
1. Nutrition :- The processes by which the organisms obtain and utilise the nutrients (food).
2. Respiration :- The process that involves breakdown of respiratory substrates through oxidation and release
of usable energy.
3. Transport :- The process in which the substances absorbed or synthesized in one part of the body are carried
to other parts of the body.
4. Excretion :- The process involved in removal of the excess or toxic wastes from the body.
5. Control and coordination :- The process which helps the living organisms to receive information from the
surroundings and behave accordingly in order to survive in the changing environment around them.
6. Growth and development :- Permanent increase in the size of the organisms is called growth. The whole
series of changes which an organism goes through during its life cycle, is called development.
7. Movement and Locomotion
DEFINITION :- The basic functions performed by living beings to sustain themselves are called life processes.
NUTRITION
Nutrients are inorganic as well as organic substances which the organisms obtain from their surroundings in order
to synthesize their body constituents and use them as a source of energy.
The process of intake of nutrients and its utilization by an organism in various biological activities.
O R
A process to transfer a source of energy from outside the body of the organism (food), to the inside is called
nutrition.
LIFE PROCESS - NUTRITION
LIFE PROCESS - NUTRITION
Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009
2
There are various types of nutrients on the basis of function they perform :-
e.g. Energy foods :– Carbohydrates and fats.
Body building foods :– Proteins and mineral salts.
Regulating foods :– Vitamins and minerals.
Modes of nutrition :– Method of obtaining food by the organism is called mode of nutrition.
 
M ode of nutrition
A utotrophic nutrition H eterotrophic nutrition
Holozoic
nutrition
Saprotrophic 
nutrition
Parasitic
nutrition
(A) Autotrophic (Holophytic) nutrition :– The mode of nutrition in which the organisms prepare (or synthesize)
their own organic food by using inorganic raw material (CO
2
 & H
2
O). They are also called autotrophs.
e.g. Plants, Photosynthetic and chemosynthetic bacteria and cyanobacteria etc.
(B) Heterotrophic nutrition :– The mode of nutrition in which the organisms derive their nutrition from other
organisms. They take ready made organic food from other dead or living plants or animals. The living organisms
showing heterotrophic nutrition, are called heterotrophs.
e.g. All animals, fungi, many bacteria and some non-green plants (insectivorous plants) and man.
Types of heterotrophic nutrition :– Depending upon the mode of obtaining food, the heterotrophic
nutrition is of following types :
 (i) Holozoic nutrition (Holo-Complete + Zoon-animal)
The mode of nutrition in which all animals take in complex solid food material is called holozoic nutrition.
It contains following steps :-
( i ) Ingestion :- Taking in complex organic food through mouth opening.
( i i ) Digestion :- Change of complex food into simple diffusible form by the action of enzymes.
( i i i )Absorption :- Passing of simple, soluble nutrients into blood or lymph.
( i v )Assimilation :- Utilization of absorbed food for various metabolic processes.
( v ) Egestion :- Expelling out the undigested food.
e.g. All animals including vertebrates and Invertebrates.
? Depending upon the type of the food habit, animals are divided into three categories :-
(a) Herbivores :– Animals that depend up on green plants are known as herbivores.
e.g. Goat, Cow, Deer, Rabbit.
(b) Carnivores :– Animals which eat flesh of other animals as food are called as carnivores.
e.g. Lion, Tiger.
( c ) Omnivores :– Animals which eat both plants and animals as food are known as omnivores.
e.g. Rat, Pigs, Crows, Cockroaches and Humans.
( i i ) Saprotrophic (Sapro - Rotten ; Trophos - Feeder) Nutrition :– In this type of nutrition the
organisms obtain their food from decaying organic substances. Organisms are also called saprotrophs.
e.g. Bacteria, Fungi.
Page 3


Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009 0
WHAT IS LIFE PROCESS ?
All the living organisms including human beings perform a number of activities such as nutrition, respiration,
excretion, growth and reproduction. These activities are characteristics of living organisms, and through such
activities they maintain their lives. These maintenance function of living organisms are known as life processes.
Chemical reactions which take place within cells or organisms during various vital activities are called
biochemical reactions.
Metabolism is a word used to describe the sum total of all the chemical and physical changes that are
constantly taking place in living matter and are necessary for life. The word metabolite refers to a substance
which undergoes various changes during metabolism. For example, carbon dioxide and water are metabolites
used in the process of photosynthesis.
The metabolic pathways are of two types :
( i ) Anabolic pathways or biosynthetic pathways in which biosynthesis of organic compounds occurs,
or in other words, complex substances are synthesized from simpler ones ; for example photosynthesis.
( i i ) Catabolic pathways in which the breakdown of complex organic substances into simpler ones occurs (as
in respiration)
In anabolic pathways or processes of anabolism energy is used (endothermic reactions), while in catabolic
pathways or catabolism, energy is released (exothermic reactions).
Criteria to define something is alive :-
1. Nutrition :- The processes by which the organisms obtain and utilise the nutrients (food).
2. Respiration :- The process that involves breakdown of respiratory substrates through oxidation and release
of usable energy.
3. Transport :- The process in which the substances absorbed or synthesized in one part of the body are carried
to other parts of the body.
4. Excretion :- The process involved in removal of the excess or toxic wastes from the body.
5. Control and coordination :- The process which helps the living organisms to receive information from the
surroundings and behave accordingly in order to survive in the changing environment around them.
6. Growth and development :- Permanent increase in the size of the organisms is called growth. The whole
series of changes which an organism goes through during its life cycle, is called development.
7. Movement and Locomotion
DEFINITION :- The basic functions performed by living beings to sustain themselves are called life processes.
NUTRITION
Nutrients are inorganic as well as organic substances which the organisms obtain from their surroundings in order
to synthesize their body constituents and use them as a source of energy.
The process of intake of nutrients and its utilization by an organism in various biological activities.
O R
A process to transfer a source of energy from outside the body of the organism (food), to the inside is called
nutrition.
LIFE PROCESS - NUTRITION
LIFE PROCESS - NUTRITION
Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009
2
There are various types of nutrients on the basis of function they perform :-
e.g. Energy foods :– Carbohydrates and fats.
Body building foods :– Proteins and mineral salts.
Regulating foods :– Vitamins and minerals.
Modes of nutrition :– Method of obtaining food by the organism is called mode of nutrition.
 
M ode of nutrition
A utotrophic nutrition H eterotrophic nutrition
Holozoic
nutrition
Saprotrophic 
nutrition
Parasitic
nutrition
(A) Autotrophic (Holophytic) nutrition :– The mode of nutrition in which the organisms prepare (or synthesize)
their own organic food by using inorganic raw material (CO
2
 & H
2
O). They are also called autotrophs.
e.g. Plants, Photosynthetic and chemosynthetic bacteria and cyanobacteria etc.
(B) Heterotrophic nutrition :– The mode of nutrition in which the organisms derive their nutrition from other
organisms. They take ready made organic food from other dead or living plants or animals. The living organisms
showing heterotrophic nutrition, are called heterotrophs.
e.g. All animals, fungi, many bacteria and some non-green plants (insectivorous plants) and man.
Types of heterotrophic nutrition :– Depending upon the mode of obtaining food, the heterotrophic
nutrition is of following types :
 (i) Holozoic nutrition (Holo-Complete + Zoon-animal)
The mode of nutrition in which all animals take in complex solid food material is called holozoic nutrition.
It contains following steps :-
( i ) Ingestion :- Taking in complex organic food through mouth opening.
( i i ) Digestion :- Change of complex food into simple diffusible form by the action of enzymes.
( i i i )Absorption :- Passing of simple, soluble nutrients into blood or lymph.
( i v )Assimilation :- Utilization of absorbed food for various metabolic processes.
( v ) Egestion :- Expelling out the undigested food.
e.g. All animals including vertebrates and Invertebrates.
? Depending upon the type of the food habit, animals are divided into three categories :-
(a) Herbivores :– Animals that depend up on green plants are known as herbivores.
e.g. Goat, Cow, Deer, Rabbit.
(b) Carnivores :– Animals which eat flesh of other animals as food are called as carnivores.
e.g. Lion, Tiger.
( c ) Omnivores :– Animals which eat both plants and animals as food are known as omnivores.
e.g. Rat, Pigs, Crows, Cockroaches and Humans.
( i i ) Saprotrophic (Sapro - Rotten ; Trophos - Feeder) Nutrition :– In this type of nutrition the
organisms obtain their food from decaying organic substances. Organisms are also called saprotrophs.
e.g. Bacteria, Fungi.
Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009 2
( i i i )Parasitic nutrition (para-other) :–
The mode of nutrition in which one organism (called parasite) derive its food from other living organism
(Host) is called parasitic nutrition. e.g. Tape worm, Ascaris, Plasmodium, Liver flukes, Cuscuta etc.
Differences between Autotrophic & Heterotrophic nutrition :-
Characters Autotrophic Nutrition Heterotrophic nutrition
( 1 ) Source of Energy Sunlight or chemical energy Readymade food
( 2 ) Mode of Nutrition Photosynthesis or Chemosynthesis Feeding upon dead or living plants
or animals
( 3 ) Occurrrence Found in green plants, Found in Animals, fungi,
Blue-green algae, certain Most of the bacteria
Bacteria
Differences between holozoic and saprotrophic nutrition :-
Feature Holozoic nutrition Saprotrophic nutrition
1. Nature of food Solid food (Whole plant or animal Liquid food (Dead and decaying organic
or their parts) is ingested matter) is ingested
2. Site of digestion Inside the body form Outside the body as enzymes are
released on the food material that
convert solid food into simple soluble
Examples Most of the Animals Fungi – Yeast, Slime moulds, Bacteria.
DO YOU KN OW ?
Animals which depend upon the blood of other animals known as sanguivores.
e.g. Bedbug, Mosquito, Leech etc.
Some organisms take in predigested food through their body wall by the process of diffusion. This
process of nutrition is known as osmotrophic nutrition.
e.g. Tapeworm, Trypanosoma.
Mutualistic nutrition :– The mutualistic nutrition can be defined as the interdependent nutrition in which
each organism is dependent mutually on the other.
e.g. The lichens share mutualistic nutrition between a fungus and a Algae.
Review Questions
FILL IN THE BLANKS :
 1. An organism which manufactures its own food from simple inorganic raw materials is known as ___________.
 2. Organisms which feed upon dead and decaying organic matter are known as ___________.
 3. ___________ and ___________ are examples of saprophytes.
 4. Yeast is ___________ in nutrition.
 5. Amarbel is ___________ in nutrition.
 6. Define life process.
 7. Define nutrition.
 8. What is heterotrophic mode of nutrition ?
 9. What criteria do we use to decide whether something is alive ?
 10. What processes would you consider essential for maintaining life ?
Page 4


Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009 0
WHAT IS LIFE PROCESS ?
All the living organisms including human beings perform a number of activities such as nutrition, respiration,
excretion, growth and reproduction. These activities are characteristics of living organisms, and through such
activities they maintain their lives. These maintenance function of living organisms are known as life processes.
Chemical reactions which take place within cells or organisms during various vital activities are called
biochemical reactions.
Metabolism is a word used to describe the sum total of all the chemical and physical changes that are
constantly taking place in living matter and are necessary for life. The word metabolite refers to a substance
which undergoes various changes during metabolism. For example, carbon dioxide and water are metabolites
used in the process of photosynthesis.
The metabolic pathways are of two types :
( i ) Anabolic pathways or biosynthetic pathways in which biosynthesis of organic compounds occurs,
or in other words, complex substances are synthesized from simpler ones ; for example photosynthesis.
( i i ) Catabolic pathways in which the breakdown of complex organic substances into simpler ones occurs (as
in respiration)
In anabolic pathways or processes of anabolism energy is used (endothermic reactions), while in catabolic
pathways or catabolism, energy is released (exothermic reactions).
Criteria to define something is alive :-
1. Nutrition :- The processes by which the organisms obtain and utilise the nutrients (food).
2. Respiration :- The process that involves breakdown of respiratory substrates through oxidation and release
of usable energy.
3. Transport :- The process in which the substances absorbed or synthesized in one part of the body are carried
to other parts of the body.
4. Excretion :- The process involved in removal of the excess or toxic wastes from the body.
5. Control and coordination :- The process which helps the living organisms to receive information from the
surroundings and behave accordingly in order to survive in the changing environment around them.
6. Growth and development :- Permanent increase in the size of the organisms is called growth. The whole
series of changes which an organism goes through during its life cycle, is called development.
7. Movement and Locomotion
DEFINITION :- The basic functions performed by living beings to sustain themselves are called life processes.
NUTRITION
Nutrients are inorganic as well as organic substances which the organisms obtain from their surroundings in order
to synthesize their body constituents and use them as a source of energy.
The process of intake of nutrients and its utilization by an organism in various biological activities.
O R
A process to transfer a source of energy from outside the body of the organism (food), to the inside is called
nutrition.
LIFE PROCESS - NUTRITION
LIFE PROCESS - NUTRITION
Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009
2
There are various types of nutrients on the basis of function they perform :-
e.g. Energy foods :– Carbohydrates and fats.
Body building foods :– Proteins and mineral salts.
Regulating foods :– Vitamins and minerals.
Modes of nutrition :– Method of obtaining food by the organism is called mode of nutrition.
 
M ode of nutrition
A utotrophic nutrition H eterotrophic nutrition
Holozoic
nutrition
Saprotrophic 
nutrition
Parasitic
nutrition
(A) Autotrophic (Holophytic) nutrition :– The mode of nutrition in which the organisms prepare (or synthesize)
their own organic food by using inorganic raw material (CO
2
 & H
2
O). They are also called autotrophs.
e.g. Plants, Photosynthetic and chemosynthetic bacteria and cyanobacteria etc.
(B) Heterotrophic nutrition :– The mode of nutrition in which the organisms derive their nutrition from other
organisms. They take ready made organic food from other dead or living plants or animals. The living organisms
showing heterotrophic nutrition, are called heterotrophs.
e.g. All animals, fungi, many bacteria and some non-green plants (insectivorous plants) and man.
Types of heterotrophic nutrition :– Depending upon the mode of obtaining food, the heterotrophic
nutrition is of following types :
 (i) Holozoic nutrition (Holo-Complete + Zoon-animal)
The mode of nutrition in which all animals take in complex solid food material is called holozoic nutrition.
It contains following steps :-
( i ) Ingestion :- Taking in complex organic food through mouth opening.
( i i ) Digestion :- Change of complex food into simple diffusible form by the action of enzymes.
( i i i )Absorption :- Passing of simple, soluble nutrients into blood or lymph.
( i v )Assimilation :- Utilization of absorbed food for various metabolic processes.
( v ) Egestion :- Expelling out the undigested food.
e.g. All animals including vertebrates and Invertebrates.
? Depending upon the type of the food habit, animals are divided into three categories :-
(a) Herbivores :– Animals that depend up on green plants are known as herbivores.
e.g. Goat, Cow, Deer, Rabbit.
(b) Carnivores :– Animals which eat flesh of other animals as food are called as carnivores.
e.g. Lion, Tiger.
( c ) Omnivores :– Animals which eat both plants and animals as food are known as omnivores.
e.g. Rat, Pigs, Crows, Cockroaches and Humans.
( i i ) Saprotrophic (Sapro - Rotten ; Trophos - Feeder) Nutrition :– In this type of nutrition the
organisms obtain their food from decaying organic substances. Organisms are also called saprotrophs.
e.g. Bacteria, Fungi.
Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009 2
( i i i )Parasitic nutrition (para-other) :–
The mode of nutrition in which one organism (called parasite) derive its food from other living organism
(Host) is called parasitic nutrition. e.g. Tape worm, Ascaris, Plasmodium, Liver flukes, Cuscuta etc.
Differences between Autotrophic & Heterotrophic nutrition :-
Characters Autotrophic Nutrition Heterotrophic nutrition
( 1 ) Source of Energy Sunlight or chemical energy Readymade food
( 2 ) Mode of Nutrition Photosynthesis or Chemosynthesis Feeding upon dead or living plants
or animals
( 3 ) Occurrrence Found in green plants, Found in Animals, fungi,
Blue-green algae, certain Most of the bacteria
Bacteria
Differences between holozoic and saprotrophic nutrition :-
Feature Holozoic nutrition Saprotrophic nutrition
1. Nature of food Solid food (Whole plant or animal Liquid food (Dead and decaying organic
or their parts) is ingested matter) is ingested
2. Site of digestion Inside the body form Outside the body as enzymes are
released on the food material that
convert solid food into simple soluble
Examples Most of the Animals Fungi – Yeast, Slime moulds, Bacteria.
DO YOU KN OW ?
Animals which depend upon the blood of other animals known as sanguivores.
e.g. Bedbug, Mosquito, Leech etc.
Some organisms take in predigested food through their body wall by the process of diffusion. This
process of nutrition is known as osmotrophic nutrition.
e.g. Tapeworm, Trypanosoma.
Mutualistic nutrition :– The mutualistic nutrition can be defined as the interdependent nutrition in which
each organism is dependent mutually on the other.
e.g. The lichens share mutualistic nutrition between a fungus and a Algae.
Review Questions
FILL IN THE BLANKS :
 1. An organism which manufactures its own food from simple inorganic raw materials is known as ___________.
 2. Organisms which feed upon dead and decaying organic matter are known as ___________.
 3. ___________ and ___________ are examples of saprophytes.
 4. Yeast is ___________ in nutrition.
 5. Amarbel is ___________ in nutrition.
 6. Define life process.
 7. Define nutrition.
 8. What is heterotrophic mode of nutrition ?
 9. What criteria do we use to decide whether something is alive ?
 10. What processes would you consider essential for maintaining life ?
Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009
4
Nutrition in unicellular organisms (Example – A m o e b a) :–
? Food – Amoeba is a holozoic and omnivorous animal. It feeds upon microscopic organisms like bacteria,
Paramecium, Diatoms, Algae and dead organic matter.
Mechanisms. Nutrition in Amoeba involves the following steps:
( i ) Ingestion:– Amoeba has no mouth, so ingestion may occur at any point of body surface but generally it
occurs at the advancing end of the body. Ingestion occurs with the help of pseudopodia.  The opening
of food cup gradually becomes narrower and narrower, and finally closes. So the food is finally enveloped
and taken inside a food-vacuole (called phagosome) along with a drop of water.
( i i ) Digestion:–  Amoeba shows intracellular and vacuolar digestion. In the cytoplasm, food vacuole fuses
with lysosomes containing digestive enzymes. In this , the complex and non-diffusible nutrients are changed
into simple and diffusible nutrients. Medium inside the food vacuole is first acidic but later becomes
alkaline, (as in the alimentary canal of man).
( i i i )Absorption and assimilation :– In absorption, the diffusible nutrients pass through vacuolar membrane
into cytoplasm by diffusion and are then distributed to all the body parts by streaming movements of
cytoplasm called cyclosis. Due to this, the size of food vacuole gradually decreases.
In the cytoplasm, a part of the absorbed food is oxidised to produce energy, most of simple nutrients are
combined to synthesize complex compounds.
( i v )Egestion :– Amoeba has no anus, so egestion may occur at any point on the body surface.
F ood cup
F ood
Pseudopodia
extended
A . I ngestion
B . E gestion
F ood v acuole U ndigested
F ood R esidue
COMPETITION WINDOW
1. Food :- The substance which is palatable, delicious enough and energy provider is called food.
Chemically food consists of six essential components :-
( i ) Carbohydrates (ii) Fats (iii) Proteins (iv) Minerals (v) Vitamins (vi) Water
2. Digestion :- Digestion is a catabolic process, in which the complex, non-diffusable and larger components of
the food, are broken down into their respective simpler, diffusable and smaller form with the help of various
hydrolytic enzymes in the alimentary canal of living organisms.
3. Intracellular and Extra-cellular Digestion :-
Intracellular Digestion : This type of digestion occur inside the cell cytoplasm. The food inside the cell occurs
as food vacuole. The digestive enzyme in this case are secreted inside the cell. They digest the contents of the
food vacuole. So the entire process of digestion occurs inside the cell. e.g. Protozoans [Amoeba], Sponges
Extracellular Digestion :- It takes place outside the cell [i.e. in the intercellular space or a cavity formed
by many cells or tissue]. In all animals this cavity is found as a large canal, called Alimentary canal.
4. Hydrolysis :- It is a kind of catabolic reaction in which a compound is broken [lysis – break] down into
smaller compounds, with the help [addition] of water [hydro = water].
5. Carbohydrates :- These are the hydrates of carbon in which the ratio among carbon, hydrogen & oxygen
is 1 : 2 : 1. Carbohydrates are the quickest source of energy.
Page 5


Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009 0
WHAT IS LIFE PROCESS ?
All the living organisms including human beings perform a number of activities such as nutrition, respiration,
excretion, growth and reproduction. These activities are characteristics of living organisms, and through such
activities they maintain their lives. These maintenance function of living organisms are known as life processes.
Chemical reactions which take place within cells or organisms during various vital activities are called
biochemical reactions.
Metabolism is a word used to describe the sum total of all the chemical and physical changes that are
constantly taking place in living matter and are necessary for life. The word metabolite refers to a substance
which undergoes various changes during metabolism. For example, carbon dioxide and water are metabolites
used in the process of photosynthesis.
The metabolic pathways are of two types :
( i ) Anabolic pathways or biosynthetic pathways in which biosynthesis of organic compounds occurs,
or in other words, complex substances are synthesized from simpler ones ; for example photosynthesis.
( i i ) Catabolic pathways in which the breakdown of complex organic substances into simpler ones occurs (as
in respiration)
In anabolic pathways or processes of anabolism energy is used (endothermic reactions), while in catabolic
pathways or catabolism, energy is released (exothermic reactions).
Criteria to define something is alive :-
1. Nutrition :- The processes by which the organisms obtain and utilise the nutrients (food).
2. Respiration :- The process that involves breakdown of respiratory substrates through oxidation and release
of usable energy.
3. Transport :- The process in which the substances absorbed or synthesized in one part of the body are carried
to other parts of the body.
4. Excretion :- The process involved in removal of the excess or toxic wastes from the body.
5. Control and coordination :- The process which helps the living organisms to receive information from the
surroundings and behave accordingly in order to survive in the changing environment around them.
6. Growth and development :- Permanent increase in the size of the organisms is called growth. The whole
series of changes which an organism goes through during its life cycle, is called development.
7. Movement and Locomotion
DEFINITION :- The basic functions performed by living beings to sustain themselves are called life processes.
NUTRITION
Nutrients are inorganic as well as organic substances which the organisms obtain from their surroundings in order
to synthesize their body constituents and use them as a source of energy.
The process of intake of nutrients and its utilization by an organism in various biological activities.
O R
A process to transfer a source of energy from outside the body of the organism (food), to the inside is called
nutrition.
LIFE PROCESS - NUTRITION
LIFE PROCESS - NUTRITION
Life Process & Nutrition – Aadhar OYCRP
 97/1, 3F, Adhchini, Sri Aurobindo Marg, Near NCERT, New Delhi |  011-32044009
2
There are various types of nutrients on the basis of function they perform :-
e.g. Energy foods :– Carbohydrates and fats.
Body building foods :– Proteins and mineral salts.
Regulating foods :– Vitamins and minerals.
Modes of nutrition :– Method of obtaining food by the organism is called mode of nutrition.
 
M ode of nutrition
A utotrophic nutrition H eterotrophic nutrition
Holozoic
nutrition
Saprotrophic 
nutrition
Parasitic
nutrition
(A) Autotrophic (Holophytic) nutrition :– The mode of nutrition in which the organisms prepare (or synthesize)
their own organic food by using inorganic raw material (CO
2
 & H
2
O). They are also called autotrophs.
e.g. Plants, Photosynthetic and chemosynthetic bacteria and cyanobacteria etc.
(B) Heterotrophic nutrition :– The mode of nutrition in which the organisms derive their nutrition from other
organisms. They take ready made organic food from other dead or living plants or animals. The living organisms
showing heterotrophic nutrition, are called heterotrophs.
e.g. All animals, fungi, many bacteria and some non-green plants (insectivorous plants) and man.
Types of heterotrophic nutrition :– Depending upon the mode of obtaining food, the heterotrophic
nutrition is of following types :
 (i) Holozoic nutrition (Holo-Complete + Zoon-animal)
The mode of nutrition in which all animals take in complex solid food material is called holozoic nutrition.
It contains following steps :-
( i ) Ingestion :- Taking in complex organic food through mouth opening.
( i i ) Digestion :- Change of complex food into simple diffusible form by the action of enzymes.
( i i i )Absorption :- Passing of simple, soluble nutrients into blood or lymph.
( i v )Assimilation :- Utilization of absorbed food for various metabolic processes.
( v ) Egestion :- Expelling out the undigested food.
e.g. All animals including vertebrates and Invertebrates.
? Depending upon the type of the food habit, animals are divided into three categories :-
(a) Herbivores :– Animals that depend up on green plants are known as herbivores.
e.g. Goat, Cow, Deer, Rabbit.
(b) Carnivores :– Animals which eat flesh of other animals as food are called as carnivores.
e.g. Lion, Tiger.
( c ) Omnivores :– Animals which eat both plants and animals as food are known as omnivores.
e.g. Rat, Pigs, Crows, Cockroaches and Humans.
( i i ) Saprotrophic (Sapro - Rotten ; Trophos - Feeder) Nutrition :– In this type of nutrition the
organisms obtain their food from decaying organic substances. Organisms are also called saprotrophs.
e.g. Bacteria, Fungi.
Life Process & Nutrition – Aadhar OYCRP
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( i i i )Parasitic nutrition (para-other) :–
The mode of nutrition in which one organism (called parasite) derive its food from other living organism
(Host) is called parasitic nutrition. e.g. Tape worm, Ascaris, Plasmodium, Liver flukes, Cuscuta etc.
Differences between Autotrophic & Heterotrophic nutrition :-
Characters Autotrophic Nutrition Heterotrophic nutrition
( 1 ) Source of Energy Sunlight or chemical energy Readymade food
( 2 ) Mode of Nutrition Photosynthesis or Chemosynthesis Feeding upon dead or living plants
or animals
( 3 ) Occurrrence Found in green plants, Found in Animals, fungi,
Blue-green algae, certain Most of the bacteria
Bacteria
Differences between holozoic and saprotrophic nutrition :-
Feature Holozoic nutrition Saprotrophic nutrition
1. Nature of food Solid food (Whole plant or animal Liquid food (Dead and decaying organic
or their parts) is ingested matter) is ingested
2. Site of digestion Inside the body form Outside the body as enzymes are
released on the food material that
convert solid food into simple soluble
Examples Most of the Animals Fungi – Yeast, Slime moulds, Bacteria.
DO YOU KN OW ?
Animals which depend upon the blood of other animals known as sanguivores.
e.g. Bedbug, Mosquito, Leech etc.
Some organisms take in predigested food through their body wall by the process of diffusion. This
process of nutrition is known as osmotrophic nutrition.
e.g. Tapeworm, Trypanosoma.
Mutualistic nutrition :– The mutualistic nutrition can be defined as the interdependent nutrition in which
each organism is dependent mutually on the other.
e.g. The lichens share mutualistic nutrition between a fungus and a Algae.
Review Questions
FILL IN THE BLANKS :
 1. An organism which manufactures its own food from simple inorganic raw materials is known as ___________.
 2. Organisms which feed upon dead and decaying organic matter are known as ___________.
 3. ___________ and ___________ are examples of saprophytes.
 4. Yeast is ___________ in nutrition.
 5. Amarbel is ___________ in nutrition.
 6. Define life process.
 7. Define nutrition.
 8. What is heterotrophic mode of nutrition ?
 9. What criteria do we use to decide whether something is alive ?
 10. What processes would you consider essential for maintaining life ?
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4
Nutrition in unicellular organisms (Example – A m o e b a) :–
? Food – Amoeba is a holozoic and omnivorous animal. It feeds upon microscopic organisms like bacteria,
Paramecium, Diatoms, Algae and dead organic matter.
Mechanisms. Nutrition in Amoeba involves the following steps:
( i ) Ingestion:– Amoeba has no mouth, so ingestion may occur at any point of body surface but generally it
occurs at the advancing end of the body. Ingestion occurs with the help of pseudopodia.  The opening
of food cup gradually becomes narrower and narrower, and finally closes. So the food is finally enveloped
and taken inside a food-vacuole (called phagosome) along with a drop of water.
( i i ) Digestion:–  Amoeba shows intracellular and vacuolar digestion. In the cytoplasm, food vacuole fuses
with lysosomes containing digestive enzymes. In this , the complex and non-diffusible nutrients are changed
into simple and diffusible nutrients. Medium inside the food vacuole is first acidic but later becomes
alkaline, (as in the alimentary canal of man).
( i i i )Absorption and assimilation :– In absorption, the diffusible nutrients pass through vacuolar membrane
into cytoplasm by diffusion and are then distributed to all the body parts by streaming movements of
cytoplasm called cyclosis. Due to this, the size of food vacuole gradually decreases.
In the cytoplasm, a part of the absorbed food is oxidised to produce energy, most of simple nutrients are
combined to synthesize complex compounds.
( i v )Egestion :– Amoeba has no anus, so egestion may occur at any point on the body surface.
F ood cup
F ood
Pseudopodia
extended
A . I ngestion
B . E gestion
F ood v acuole U ndigested
F ood R esidue
COMPETITION WINDOW
1. Food :- The substance which is palatable, delicious enough and energy provider is called food.
Chemically food consists of six essential components :-
( i ) Carbohydrates (ii) Fats (iii) Proteins (iv) Minerals (v) Vitamins (vi) Water
2. Digestion :- Digestion is a catabolic process, in which the complex, non-diffusable and larger components of
the food, are broken down into their respective simpler, diffusable and smaller form with the help of various
hydrolytic enzymes in the alimentary canal of living organisms.
3. Intracellular and Extra-cellular Digestion :-
Intracellular Digestion : This type of digestion occur inside the cell cytoplasm. The food inside the cell occurs
as food vacuole. The digestive enzyme in this case are secreted inside the cell. They digest the contents of the
food vacuole. So the entire process of digestion occurs inside the cell. e.g. Protozoans [Amoeba], Sponges
Extracellular Digestion :- It takes place outside the cell [i.e. in the intercellular space or a cavity formed
by many cells or tissue]. In all animals this cavity is found as a large canal, called Alimentary canal.
4. Hydrolysis :- It is a kind of catabolic reaction in which a compound is broken [lysis – break] down into
smaller compounds, with the help [addition] of water [hydro = water].
5. Carbohydrates :- These are the hydrates of carbon in which the ratio among carbon, hydrogen & oxygen
is 1 : 2 : 1. Carbohydrates are the quickest source of energy.
Life Process & Nutrition – Aadhar OYCRP
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On the basis of their composition, carbohydrates are of following types :
(a) Monosaccharides :- The simplest sugars are called monosaccharides. These sugars cannot be further
degraded to produce more sugars. e.g. Glucose, Fructose, Galactose, Ribose and Deoxyribose.
(b) Oligosaccharides :- These are complex sugars, formed by the polymerisation of a few [1 to 10] units
of monosaccharides.
Sucrose – Glucose + Fructose
Maltose – Glucose + Glucose
Lactose – Glucose + Galactose
(c) Polysaccharides :- These are most complex carbohydrates, which are the polymers of thousand of units
of monosaccharides. e.g. Starch – Stored food in plants, Glycogen – Stored food material in Animals.
Cellulose – Constituent of cell wall.
6. Fats :- These are energy rich compounds. These are the esters of higher fatty acids. [Esters are formed by
the addition of alcohol with acids] Alcohol – generally Glycerol.
7. Proteins :- Proteins are the polymers of amino acids. Amino acids are held together by means of peptide
bond to form polypeptide chains.
8. On the basis of  gross size of food, the mechanism in different animals may be of two main types :-
(a) Microphagy – Feeding on microscopic organisms. e.g. Amoeba, Paramecium.
(b) Macrophagy – Feeding on larger forms of organisms. e.g. Majority of non-chordates and some chordates.
9. In Paramecium, ingestion is aided by beating of cillia. It has definite food passage, mouth (cytostome) and anus (cytopyge).
10. Food vacuole is commonly called temporary stomach or gastriole as it is the site of storage of food.
11. Most common mode of ingestion in Amoeba is circumvallation. In this, pseudopodia extend and form a cup-
like structure, called food cup, around the prey.
DIGESTIVE SYSTEM OF HUMAN :-
Human digestive system consists of the alimentary canal and digestive glands and it involves mastication,
swallowing, digestion of food and elimination of undigested matter.
It consists two parts :-
[A] Alimentary canal:– The alimentary canal is basically a long tube extending from the mouth to the anus.
It is differentiated into following parts.
A limentary canal
M outh
D uodenum Il eum
Sm all I ntestine L arge I ntestine
Jejunum
B ucco-Pharyngeal cav ity Oesophagus Stom ach I ntestine
Caecum R ectum Colon
Read More
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