Page 68 - Viva ICSE Science 4 : E-book

Functions of leaves

• Green leaves prepare food by a process called photosynthesis. The leaves take
carbon dioxide from the air and combine it with water in the presence of sunlight

and chlorophyll to make food for the whole plant. Chlorophyll is the green colour
pigment that helps leaves to absorb sunlight in order to make their own food and
grow. Thus, leaves are also called food factories of the plant.

• The food prepared by the leaves

during the process of photosynthesis is
carbon dioxide
glucose (sugar). This food is transported (from air)
throughout the plant by the stem and
sunlight
branches. Extra glucose in leaves is (from the sun)
stored as starch.

• Leaves have stomata that help in the
exchange of gases and transpiration.
chlorophyll
Transpiration is the process of loss of (in the leaf)
water from plants, especially from the

leaves in the form of water vapour.
water
It occurs through the small stomatal (from soil)
openings present on the leaves. This

happens when stomata opens to take
up carbon dioxide from the air to carry Photosynthesis

out photosynthesis.
• Transpiration also cools the plants and helps in the transport of nutrients from roots

to shoots.

• Leaves also store extra food in some plants like lettuce and spinach.

TIME TO REVISE

Correct the following statements.

1. Thick and strong stem of a tree is called climber.
2. Food factory of green plants are its roots.

3. Sunlight is absorbed by the leaves with the help of stomata.
4. Photosynthesis cools the plants.

5. Extra starch is stored in the form of glucose.

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