Question

Main function of leaf is
A. Transpiration
B. Exchange of gases
C. Photosynthesis
D. Cooling

Answer 1

Hint: Leaf is a lateral, usually flattened structure present on the stem. Leaves develop at the node and are one of the most important vegetative organs for carrying out the main function.

Complete answer:
The main function of the leaf is photosynthesis. Photosynthesis is a physio-chemical process in which plants use light energy from the sun to drive the synthesis of organic compounds. It is the primary source of all food and oxygen present on earth. Photosynthesis occurs in the green parts of the leaves in the presence of light. The photosynthetic pigment present in chlorophyll converts solar energy into chemical energy.
Another important process carried out by leaf is transpiration. Transpiration refers to the evaporative loss of water by the stomata present in the leaves. The transpiration process cools the surface of leaves by evaporative cooling.
Besides the loss of water vapour in transpiration, exchange of gases takes place through the pores called stomata present on the leaves.
So, the correct answer is (c) ‘Photosynthesis’.

Note:
- All living forms depend on sunlight for energy.
- An actively photosynthesizing plant has an insatiable need for water. Hence available water is the limiting factor for photosynthesis.
- Stomata are open during the day in most of the plants whereas, in some plants living in arid conditions, stomata open during the night.