Question

Sunken stomata occur in
A) Mesophytes
B) Xerophytes
C) Hygrophytes
D) Hydrophytes

Answer 1

Sunken stomata is basically the stomata which is found sunk in a pit, and protects the escaping water vapour from air currents, decreasing water loss from the leaf. In arid environments one of their adaptations to preserve water sunken stomata are commonly found in plants.

Complete answer:

Option A: Mesophytes are terrestrial plants, they require moderate amounts of water. They have less stomata than hydrophytes. Therefore, this is the incorrect option.
Option B: Sunken stomata are commonly found in plants in arid environments. As sunken stomata are features of desert, dry environmental plants are referred to as xerophytes. Therefore, this is the correct option.
Some xerophytic plants are – Agave, pine, acacia, cactaceae family, liliaceae, crassulaceae family etc.
The stomata remain closed during the day to prevent loss of water, thus preserving water and are open during the night. In nerium, stomata are sunken in crypts, having hair they reduce the heating effect of sunlight and reduce transpiration as they are not directly exposed to air and sunlight.
Option C: Hydrophytes are plants which grow in wet conditions and they have stomata mostly in the upper epidermis. Therefore, this is the incorrect option.
Option D: Hydrophytes – they live in water and are called aquatic plants and they have stomata on the upper epidermis as the lower epidermis is in direct contact with the water. Therefore, this is the incorrect option.

Thus, the correct answer is option (B) Xerophytes.

Note: Function of stomata are as follows,
It opens and closes the pores in the leaves for an exchange of gases.
It allows the plant to take in carbon dioxide and give out oxygen for photosynthesis.
Depending on the weather conditions, it closes or opens its pores to keep the moisture content developed.