Life Process Notes | Study Science for Class 10 - Short Notes - Class 10

 Page 1


Chapter 6 Life Processes
Introduction
? All the processes such as respiration, nutrition, circulation, excretion, etc. that are necessary for
the survival of the living organisms are known as life processes.
? In unicellular organisms, all these life processes are carried out by that single cell.
? In multicellular organisms, well-developed systems are present to carry out the processes.
Nutrition and Modes of Nutrition
? The process of acquiring food that is needed for nourishment and sustenance of the organism is
called nutrition.
? There are two main modes of nutrition, autotrophic and heterotrophic.
? Heterotrophic nutrition has subtypes as holozoic, saprophytic, and parasitic nutrition.
Autotrophic Nutrition
? If an organism can nourish itself by making its own food using sunlight or chemicals such mode
of nutrition is called autotrophic nutrition.
? For example, green plants use the autotrophic mode of nutrition. Plants photosynthesize (use light
energy) and are called photoautotrophs.
? Few bacteria use chemicals to derive energy and are called chemoautotrophs.
Photosynthesis
? For photosynthesis to occur, carbon dioxide, water, sunlight, and chlorophyll are the required raw
materials.
? Sunlight provides energy, chlorophyll is used to absorb the sunlight, carbon dioxide is reduced to
carbohydrates, and water is oxidized to release oxygen.
? Water is taken up from the soil through the roots.
? The site where photosynthesis occurs is known as chloroplast.
? They contain a green color pigment known as chlorophyll that traps sunlight for photosynthesis.
Steps of the photosynthesis are as follows-
? Absorption of light by chlorophyll.
? Conversion of light energy into chemical energy.
? Splitting of water into hydrogen and oxygen.
Page 2


Chapter 6 Life Processes
Introduction
? All the processes such as respiration, nutrition, circulation, excretion, etc. that are necessary for
the survival of the living organisms are known as life processes.
? In unicellular organisms, all these life processes are carried out by that single cell.
? In multicellular organisms, well-developed systems are present to carry out the processes.
Nutrition and Modes of Nutrition
? The process of acquiring food that is needed for nourishment and sustenance of the organism is
called nutrition.
? There are two main modes of nutrition, autotrophic and heterotrophic.
? Heterotrophic nutrition has subtypes as holozoic, saprophytic, and parasitic nutrition.
Autotrophic Nutrition
? If an organism can nourish itself by making its own food using sunlight or chemicals such mode
of nutrition is called autotrophic nutrition.
? For example, green plants use the autotrophic mode of nutrition. Plants photosynthesize (use light
energy) and are called photoautotrophs.
? Few bacteria use chemicals to derive energy and are called chemoautotrophs.
Photosynthesis
? For photosynthesis to occur, carbon dioxide, water, sunlight, and chlorophyll are the required raw
materials.
? Sunlight provides energy, chlorophyll is used to absorb the sunlight, carbon dioxide is reduced to
carbohydrates, and water is oxidized to release oxygen.
? Water is taken up from the soil through the roots.
? The site where photosynthesis occurs is known as chloroplast.
? They contain a green color pigment known as chlorophyll that traps sunlight for photosynthesis.
Steps of the photosynthesis are as follows-
? Absorption of light by chlorophyll.
? Conversion of light energy into chemical energy.
? Splitting of water into hydrogen and oxygen.
? Finally, reduction of carbon dioxide into carbohydrates.
The overall equation of photosynthesis is:
Stomata
? Stomata are pores on the leaves that help in the exchange of gases.
? They are mostly found on the underside of the leaf.
? Each stoma is guarded by guard cells, which control the opening and closing of the pore.
? The water content of the guard cells is responsible for their function.
Heterotrophic Nutrition
? In this mode of nutrition, an organism is unable to synthesize its own food. It is of the following
types-
Page 3


Chapter 6 Life Processes
Introduction
? All the processes such as respiration, nutrition, circulation, excretion, etc. that are necessary for
the survival of the living organisms are known as life processes.
? In unicellular organisms, all these life processes are carried out by that single cell.
? In multicellular organisms, well-developed systems are present to carry out the processes.
Nutrition and Modes of Nutrition
? The process of acquiring food that is needed for nourishment and sustenance of the organism is
called nutrition.
? There are two main modes of nutrition, autotrophic and heterotrophic.
? Heterotrophic nutrition has subtypes as holozoic, saprophytic, and parasitic nutrition.
Autotrophic Nutrition
? If an organism can nourish itself by making its own food using sunlight or chemicals such mode
of nutrition is called autotrophic nutrition.
? For example, green plants use the autotrophic mode of nutrition. Plants photosynthesize (use light
energy) and are called photoautotrophs.
? Few bacteria use chemicals to derive energy and are called chemoautotrophs.
Photosynthesis
? For photosynthesis to occur, carbon dioxide, water, sunlight, and chlorophyll are the required raw
materials.
? Sunlight provides energy, chlorophyll is used to absorb the sunlight, carbon dioxide is reduced to
carbohydrates, and water is oxidized to release oxygen.
? Water is taken up from the soil through the roots.
? The site where photosynthesis occurs is known as chloroplast.
? They contain a green color pigment known as chlorophyll that traps sunlight for photosynthesis.
Steps of the photosynthesis are as follows-
? Absorption of light by chlorophyll.
? Conversion of light energy into chemical energy.
? Splitting of water into hydrogen and oxygen.
? Finally, reduction of carbon dioxide into carbohydrates.
The overall equation of photosynthesis is:
Stomata
? Stomata are pores on the leaves that help in the exchange of gases.
? They are mostly found on the underside of the leaf.
? Each stoma is guarded by guard cells, which control the opening and closing of the pore.
? The water content of the guard cells is responsible for their function.
Heterotrophic Nutrition
? In this mode of nutrition, an organism is unable to synthesize its own food. It is of the following
types-
1. Holozoic nutrition is a type of nutrition where an organism takes in whole food and breaks it
inside the body. For example, Amoeba.
2. Saprophytic nutrition is nutrition in which organisms feed on dead and decaying matter. For
example, fungi.
3. Parasitic nutrition is nutrition in which organisms feed on living hosts. For example, Cuscuta.
Nutrition in Amoeba
? Amoeba feeds by holozoic mode of nutrition.
? It engulfs the food particle using pseudopodia, the process is called phagocytosis.
? The engulfed food gets enclosed in a food vacuole.
? As the food vacuole passes through the cytoplasm, digestion, absorption, and assimilation take
place.
? When the food vacuole opens to outside, egestion of undigested food takes place.
Nutrition in Human Beings
? Humans are omnivores, they can eat plant-based food as well as animal-based food.
? Being more complex, humans have a very complicated nutrition system.
? The digestive system has an alimentary canal and associated digestive glands, which together
function to nourish the body.
? There are five stages in human nutrition; Ingestion, Digestion, Absorption, Assimilation and
Egestion.
? Four stages i.e. ingestion, digestion, absorption and egestion take place in the alimentary canal
while assimilation of food takes place in the whole body.
Alimentary Canal
Page 4


Chapter 6 Life Processes
Introduction
? All the processes such as respiration, nutrition, circulation, excretion, etc. that are necessary for
the survival of the living organisms are known as life processes.
? In unicellular organisms, all these life processes are carried out by that single cell.
? In multicellular organisms, well-developed systems are present to carry out the processes.
Nutrition and Modes of Nutrition
? The process of acquiring food that is needed for nourishment and sustenance of the organism is
called nutrition.
? There are two main modes of nutrition, autotrophic and heterotrophic.
? Heterotrophic nutrition has subtypes as holozoic, saprophytic, and parasitic nutrition.
Autotrophic Nutrition
? If an organism can nourish itself by making its own food using sunlight or chemicals such mode
of nutrition is called autotrophic nutrition.
? For example, green plants use the autotrophic mode of nutrition. Plants photosynthesize (use light
energy) and are called photoautotrophs.
? Few bacteria use chemicals to derive energy and are called chemoautotrophs.
Photosynthesis
? For photosynthesis to occur, carbon dioxide, water, sunlight, and chlorophyll are the required raw
materials.
? Sunlight provides energy, chlorophyll is used to absorb the sunlight, carbon dioxide is reduced to
carbohydrates, and water is oxidized to release oxygen.
? Water is taken up from the soil through the roots.
? The site where photosynthesis occurs is known as chloroplast.
? They contain a green color pigment known as chlorophyll that traps sunlight for photosynthesis.
Steps of the photosynthesis are as follows-
? Absorption of light by chlorophyll.
? Conversion of light energy into chemical energy.
? Splitting of water into hydrogen and oxygen.
? Finally, reduction of carbon dioxide into carbohydrates.
The overall equation of photosynthesis is:
Stomata
? Stomata are pores on the leaves that help in the exchange of gases.
? They are mostly found on the underside of the leaf.
? Each stoma is guarded by guard cells, which control the opening and closing of the pore.
? The water content of the guard cells is responsible for their function.
Heterotrophic Nutrition
? In this mode of nutrition, an organism is unable to synthesize its own food. It is of the following
types-
1. Holozoic nutrition is a type of nutrition where an organism takes in whole food and breaks it
inside the body. For example, Amoeba.
2. Saprophytic nutrition is nutrition in which organisms feed on dead and decaying matter. For
example, fungi.
3. Parasitic nutrition is nutrition in which organisms feed on living hosts. For example, Cuscuta.
Nutrition in Amoeba
? Amoeba feeds by holozoic mode of nutrition.
? It engulfs the food particle using pseudopodia, the process is called phagocytosis.
? The engulfed food gets enclosed in a food vacuole.
? As the food vacuole passes through the cytoplasm, digestion, absorption, and assimilation take
place.
? When the food vacuole opens to outside, egestion of undigested food takes place.
Nutrition in Human Beings
? Humans are omnivores, they can eat plant-based food as well as animal-based food.
? Being more complex, humans have a very complicated nutrition system.
? The digestive system has an alimentary canal and associated digestive glands, which together
function to nourish the body.
? There are five stages in human nutrition; Ingestion, Digestion, Absorption, Assimilation and
Egestion.
? Four stages i.e. ingestion, digestion, absorption and egestion take place in the alimentary canal
while assimilation of food takes place in the whole body.
Alimentary Canal
Humans consist of the alimentary canal which starts from the mouth and ends at the anus. The
parts of the alimentary canal are as follows-
1. Mouth
2. Pharynx
3. Oesophagus/food pipe
4. Stomach
5. Small intestine
6. Large intestine
7. Rectum
8. Anus
Labeled diagram of the human alimentary canal-
Mouth
Page 5


Chapter 6 Life Processes
Introduction
? All the processes such as respiration, nutrition, circulation, excretion, etc. that are necessary for
the survival of the living organisms are known as life processes.
? In unicellular organisms, all these life processes are carried out by that single cell.
? In multicellular organisms, well-developed systems are present to carry out the processes.
Nutrition and Modes of Nutrition
? The process of acquiring food that is needed for nourishment and sustenance of the organism is
called nutrition.
? There are two main modes of nutrition, autotrophic and heterotrophic.
? Heterotrophic nutrition has subtypes as holozoic, saprophytic, and parasitic nutrition.
Autotrophic Nutrition
? If an organism can nourish itself by making its own food using sunlight or chemicals such mode
of nutrition is called autotrophic nutrition.
? For example, green plants use the autotrophic mode of nutrition. Plants photosynthesize (use light
energy) and are called photoautotrophs.
? Few bacteria use chemicals to derive energy and are called chemoautotrophs.
Photosynthesis
? For photosynthesis to occur, carbon dioxide, water, sunlight, and chlorophyll are the required raw
materials.
? Sunlight provides energy, chlorophyll is used to absorb the sunlight, carbon dioxide is reduced to
carbohydrates, and water is oxidized to release oxygen.
? Water is taken up from the soil through the roots.
? The site where photosynthesis occurs is known as chloroplast.
? They contain a green color pigment known as chlorophyll that traps sunlight for photosynthesis.
Steps of the photosynthesis are as follows-
? Absorption of light by chlorophyll.
? Conversion of light energy into chemical energy.
? Splitting of water into hydrogen and oxygen.
? Finally, reduction of carbon dioxide into carbohydrates.
The overall equation of photosynthesis is:
Stomata
? Stomata are pores on the leaves that help in the exchange of gases.
? They are mostly found on the underside of the leaf.
? Each stoma is guarded by guard cells, which control the opening and closing of the pore.
? The water content of the guard cells is responsible for their function.
Heterotrophic Nutrition
? In this mode of nutrition, an organism is unable to synthesize its own food. It is of the following
types-
1. Holozoic nutrition is a type of nutrition where an organism takes in whole food and breaks it
inside the body. For example, Amoeba.
2. Saprophytic nutrition is nutrition in which organisms feed on dead and decaying matter. For
example, fungi.
3. Parasitic nutrition is nutrition in which organisms feed on living hosts. For example, Cuscuta.
Nutrition in Amoeba
? Amoeba feeds by holozoic mode of nutrition.
? It engulfs the food particle using pseudopodia, the process is called phagocytosis.
? The engulfed food gets enclosed in a food vacuole.
? As the food vacuole passes through the cytoplasm, digestion, absorption, and assimilation take
place.
? When the food vacuole opens to outside, egestion of undigested food takes place.
Nutrition in Human Beings
? Humans are omnivores, they can eat plant-based food as well as animal-based food.
? Being more complex, humans have a very complicated nutrition system.
? The digestive system has an alimentary canal and associated digestive glands, which together
function to nourish the body.
? There are five stages in human nutrition; Ingestion, Digestion, Absorption, Assimilation and
Egestion.
? Four stages i.e. ingestion, digestion, absorption and egestion take place in the alimentary canal
while assimilation of food takes place in the whole body.
Alimentary Canal
Humans consist of the alimentary canal which starts from the mouth and ends at the anus. The
parts of the alimentary canal are as follows-
1. Mouth
2. Pharynx
3. Oesophagus/food pipe
4. Stomach
5. Small intestine
6. Large intestine
7. Rectum
8. Anus
Labeled diagram of the human alimentary canal-
Mouth
? The mouth is the first portion of the alimentary canal.
? The mouth consists of a muscular tongue and teeth. The cavity inside the mouth is known
as the oral cavity.
? The food digestion process begins in the mouth. Food is complex in nature.
? To break down food and absorb it, we need a biological catalyst known as enzymes.
? The mouth contains salivary glands that secrete saliva.
? Saliva contains an important enzyme known as salivary enzymes that breaks down starch
into simple sugars.
? The set of teeth helps in the mastication of food.
? The tongue has taste buds on it and thus helps in tasting the food.
? The salivary glands open also in the buccal cavity and pour saliva which initiates the
process of digestion.
Oesophagus & Stomach
Oesophagus
? The swallowed food passes into the oesophagus.
? It is a muscular tube, about 25 cm long, with a sphincter (valve/opening) at each end.
? Its function is to transport food and fluid, after being swallowed, from the mouth to the stomach.
? Food is pushed down by peristaltic movements.
Stomach
? The stomach is a thick-walled bag-like structure.
? It receives food from the oesophagus at one end and opens into the small intestine at the other
end.
? The inner lining of the stomach secretes mucous, hydrochloric acid, and digestive juices.
? Food is churned into a semi-solid mass in the stomach and is called chyme.
? Enzymes present in the gastric juice break down the food.
? Hydrochloric acid helps in the partial digestion of proteins and also kills harmful bacteria.
? Mucus secreted by the wall of the stomach resists the action of HCl on itself.
Small Intestine
? The small intestine is the longest part of the alimentary canal, about 20 feet long in humans.
? After the stomach, food then enters into the small intestine. The small intestine is larger in
herbivores due to cellulose digestion compared to carnivores.
? Complete digestion of carbohydrates, proteins, and fats occurs in the small intestine.
? The small intestine receives secretions from the pancreas and bile from the liver.