Question

Read the following passage carefully and answer the questions that follow.

Plants use solar energy to convert carbon dioxide and water into glucose and oxygen. The

glucose is stored in the form of starch in leaves and in other parts of the plant. Both glucose and

starch are forms of carbohydrate. The presence of starch in a leaf verifies the occurance of

photosynthesis.

The food prepared by green plants is used by all other living organisms. Photosynthesis also

helps in maintaining the ratio of oxygen and carbondioxide in the atmosphere. Thus, plants are

vital for maintaining life.

a. Write the overall word equation of photosynthesis.

b. If glucose is formed during photosynthesis, then why do we test for starch to find out whether

photosynthesis has taken place or not?

c. How photosynthesis helps in maintaining oxygen and carbon dioxide ratio in the atmosphere?

d. What form of energy is used by plants during photosynthesis?

e. What happens to oxygen formed during photosynthesis? [choice is for part (e) only; other questions are

compulsory]

Or

Plants are vital for maintaining life. Justify​

Answer 1

Answer:

Photosynthesis is the process of formation of organic food from carbon dioxide and water in the presence of sunlight where chlorophyll traps the solar energy in cells. Oxygen is produced as byproduct. Simple carbohydrate or sugar (e.g.glucose) is the main product from which other organic substances are formed. Excess of glucose is stored as starch to function as internal energy reserve to be used as and when required. So, we test starch instead of glucose in leaves. Starch develops a blue-black colour with iodine solution.