The maintenance functions of all living organisms must go on even when they are not doing anything particular. Even when we are just sitting in a class or even asleep, this maintenance job has to go on. These maintenance processes require energy to prevent damage and break-down of cells and tissues, which is obtained by the individual organism from the food prepared by the autotrophs, called producers. (a) Name and define the process by which green plants prepare food. [1] (b) Write chemical equation involved in the above process. [1] (c) (i) State in proper sequence the events that occur in synthesis of food by desert plants. [2] OR (c) (ii) Explain giving reasons what happens to the rate at which the green plants will prepare food (I) during cloudy weather, and (II) when stomata get blocked due to dust. [2]

(a) The process by which green plants prepare food is called photosynthesis. Photosynthesis is the process by which autotrophs take in substances from the outside and convert them into stored forms of energy. <br> (b) The chemical equation involved in photosynthesis is: $$6 ext{CO}_2 + 12 ext{H}_2 ext{O} ightarrow ext{Sunlight} ightarrow ext{C}_6 ext{H}_{12} ext{O}_6 + 6 ext{O}_2 + 6 ext{H}_2 ext{O}$$ <br> (c) (i) The events that occur in synthesis of food by desert plants are: <ol> <li> Absorption of light energy by chlorophyll. </li> <li> Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. </li> <li> Reduction of carbon dioxide to carbohydrates. </li> </ol> OR <br> (c) (ii) (I) During cloudy weather, the rate at which the green plants will prepare food will decrease. This is because the amount of sunlight available for photosynthesis is reduced. <br> (II) When stomata get blocked due to dust, the rate at which the green plants will prepare food will decrease. This is because the stomata are responsible for the exchange of gases, including carbon dioxide, which is necessary for photosynthesis.