Autotrophic nutrition

Question 1 Name the cellular organelle where photosynthesis occur?

Question 2 Define the term nutrition?

Question 3 Name two modes of nutrition?

Question 4 Define photosynthesis?

Question 5 What is autotrophic mode of nutrition?

Question 6 Give the function of stomata?

Question 7 Why are plants green?

Question 8 Write a chemical equation to show the process of photosynthesis in plants?

Question 9 What is the role of chlorophyll in photosynthesis?

Question 10 What are the necessary conditions of photosynthesis?

Question 11 Write the three main steps of photosynthesis?

Question 12 What are guard cells?

Question 13 What are the end products of photosynthesis?


The process of taking in food and utilising it is called nutrition.

A nutrient is a substance which an organism obtain from its surrounding and uses it as a source of energy.

Modes of nutrition

Autotrophic nutrition

In autotrophic nutrition,the organism makes its own food from inorganic raw material like carbon dioxide and water present in the surrounding by using sunlight.

For Ex:Green plants,autotrophic bacteria.

Those organism which can make their own food from carbon dioxide and water is called autotrophs.

Green plants contain green pigment called chlorophyll which is capable of trapping sunlight energy.

The process by which green plants make their own food from carbon dioxide and water in the presence of chlorophyll is called photosynthesis.


1)The carbon dioxide gas is taken from air,water is taken from soil,sunlight provide energy required to carry out chemical reaction,chlorophyll helps in absorbing energy from sunlight.

2)The carbon dioxide enters the leaves through tiny pores called stomata,water is transported to leaves from soil through stem and roots.

3)The end product of photosynthesis are oxygen and glucose.

4)The extra glucose is converted into starch (Carbohydrates).It is stored in the leaves of plants.

 Photosynthesis take place in 3 steps

1)Absorption of light energy by chlorophyll.

2)Conversion of light energy into chemical energy and spitting of water into hydrogen and oxygen.

3)Reduction of carbon dioxide into carbohydrates.

 Chlorophyll is present in cell organelle called chloroplast.It is the site of photosynthesis.


 Stomata is present at the surface of leaves.The stomatal pores are surrounded by guard cells.They control opening and closing of stomata.

1)When water flows in the guard cell,it swells,become curve and pores open.

2)When it loses water,guard cell shrink,become straight and pores closes.

The gaseous exchange in plant take place through stomata.

In broad leave plants,stomata is present in lower surface.

In narrow leave plants,stomata is present on lower as well as upper surface.

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