Question

The productivity of a crop begins to decline when the leaves begin to wilt mainly because
A. Flaccid mesophyll cells are incapable of photosynthesis
B. Stomata close, preventing $CO_2$ from entering the leaf
C. Oesophagus
D. Bronchi

Answer 1

Hint: Plants make their food through the process of photosynthesis. They use sunlight as their source of energy. Plants need various things for making their own food, which are chlorophyll, sunlight, carbon dioxide, water and minerals.

Complete answer:
Plants are autotrophic in nature. They produce their own food with the help of nutrition and growth. The process of making food of plants takes place in the leaves of the plant. The main principle behind the process of photosynthesis is light energy is converted into chemical energy and they usually store their food in the form of starch.

Photosynthesis is the key process for the growth of the plants. The rate of the photosynthesis depends on the required elements present during the process or not. The products formed at the end of photosynthesis are oxygen and carbohydrate.

Stomata are the small pores present on the surface of leaves which are mainly responsible for gaseous exchange. The pores are covered by cells called guard cells. It opens and closes for the exchange of gases. The closing of stomata does not allow $C{O_2}$ to enter the plant. This leads to a stoppage of the process of photosynthesis and production of food stopped. So, the productivity of a crop begins to decline when the leaves begin to wilt mainly because of loss of water.

Hence, the correct answer is option (B).

Note: The process of photosynthesis divided into two steps:
- Light Reaction
- Dark Reaction
The light reaction is the initial phase of the photosynthesis while dark reaction is used for producing glucose. Dark reaction doesn’t need light to carry out its process, so it is called a dark reaction. Glucose formed at the end of dark reaction while ATP and NADH are the end product of light reaction.