Three potted plants were kept in a dark cupboard for two days before being used for an experiment. Each plant was then put under a bell jar under different conditions for six hours . Bell jar D contains a potted plant with a small cup of sodium hydroxide solution with light pointed towards it Bell jar E contains a potted plant with light pointed towards it Bell jar F contains a potted plant with aluminium foil on top of the bell jar with light pointed towards it a)explain why their was no starch in the leaves at the end of the two days in the cupboard b)what is the purpose of sodium hydroxide put under bell jar in D?

a. There were starch in the leaves at the end of two days in the cupboard because there was no sunlight to provide the energy for photosynthesis in the dark cupboard. Also, any previously synthesized starch in the plant leaves were used by the plant for its own metabolic requirements during the period the plant was in the cupboard. Therefore, staying in the cupboard for two days destarched the leaves.

b. The purpose of sodium hydroxide put under bell jar in D is to remove any carbon dioxide that may be present under the bell jar. This is to demonstrate that even in the presence of sunlight, carbon dioxide is required for photosynthesis to occur in plants.

Explanation:

Photosythesis is the process by which green plants manufacture their food (carbohydrates which are stored as starch) in the presence of sunlight. The site of photosynthesis in plants is the leaves.

The experimental design is to study the conditions necessary for photosynthesis to occur. For photosynthesis to occur, there must be presence of sunlight, carbon dioxide and water. Carbon dioxide and water serve as the raw materials for photosynthesis while the energy required is provided by sunlight.

The answers to the observations from the experiment are given below :

a. There were starch in the leaves at the end of two days in the cupboard because there was no sunlight to provide the energy for photosynthesis in the dark cupboard. Also, any previously synthesized starch in the plant leaves were used by the plant for its own metabolic requirements during the period the plant was in the cupboard. Therefore, staying in the cupboard for two days destarched the leaves.

b. The purpose of sodium hydroxide put under bell jar in D is to remove any carbon dioxide that may be present under the bell jar. This is to demonstrate that even in the presence of sunlight, carbon dioxide is required for photosynthesis to occur in plants.