Question

A plant is kept in a dark cupboard for about 48 hours before conducting any experiment on photosynthesis to
A. Remove starch from the plant.
B. Ensure that starch is not translocated from the leaves.
C. Remove chlorophyll from the leaf of the plant.
D. Remove starch from the experimental leaf.

Answer 1

Hint: Photosynthesis is an anabolic, endothermic process carried out in plants to produce organic compounds from simple inorganic molecules in the presence of light. Starch is a stored form of glucose in plants.

Complete answer:Photosynthesis is a process in which organic compounds like carbohydrates are synthesized from simple inorganic compounds like carbon dioxide and water in the presence of chlorophyll pigment and sunlight as a source of energy and liberates out oxygen. It is also called carbon assimilation. Photosynthesis is anabolic (due to the synthesis of glucose) and endothermic reaction (requires energy input).
Photosynthesis is important for two reasons:
1. It is the primary source of food on Earth.
2. It is responsible for the release of oxygen in the atmosphere, as in the absence of oxygen all organisms will die.
Starch is a stored form of glucose in plants. Before experimenting on photosynthesis, the plant is kept in the dark for some hours to remove starch from the experimental leaf. This is necessary to ensure that we get accurate results after the experiment likes to show that carbon dioxide is required for photosynthesis or to show that photosynthesis is carried out only in green leaves.
So our correct answer is option D. remove starch from the experimental leaf.

Note:In photosynthesis where molecules of water are used as a substrate, oxygen produced comes from water and not from carbon dioxide molecules.