(a) The process by which green plants make their own food (like glucose) from carbon dioxide and water by using sunlight energy in the presence of chlorophyll is called photosynthesis.

(b) 6CO₂ + 6H₂O + Light Energy + chlorophyll + (photosynthesis) → C₆H₁₂O₆ + 6O₂

(c) The process of photosynthesis takes place in the green leaves of a plant. The carbon dioxide gas required for making food is taken by the plant leaves from the air which enters the leaves through tiny pores called stomata. Water required for making food is taken from the soil which is transported to the leaves from the soil through the roots and the stem. The sunlight provides energy required to carry out the chemical reactions involved in the preparation of food. The green pigment called chlorophyll absorbs sunlight energy.

The photosynthesis takes place in three steps:

(i) Absorption of sunlight energy by chlorophyll.

(ii) Conversion of light energy into chemical energy and splitting of water into hydrogen and oxygen by light energy.

(iii) Reduction of carbon dioxide by hydrogen to form carbohydrates like glucose by utilising the chemical energy.