Question

Guttation occurs through
A. Stomata
B. Lenticels
C. Cuticle
D. Hydathodes

Answer 1

Hint: Most of the water absorbed is lost through the aerial part of the plant into air by the process called as transpiration through stomata and guttation through the margins of leaves. Very little amount of water (less than 2%) is used up in various metabolic activities in the plant body.

Complete answer:
The process of exudation of sap on the tips or edges of leaves in plants is known as guttation. It occurs only under certain conditions like cold and high relative humidity in the atmosphere. It performs the process with the help of very specialized structures called hydathodes. They are generally restricted to the apex or the sides of the margins of leaves. Structurally, hydathodes consist of an easy pore within the epidermal layer found at the tip.

When the soil contains the high water content in it, the water enters in the roots because the water potential of the roots is less than that in the soil. The water gets accumulated in the plant and creates little root pressure. Root pressure forces water to exude through leaf tips, hydathodes or water glands and forms droplets. Guttation is observed when transpiration is suppressed. Therefore, the process of guttation takes place with the help of hydathodes.

So the correct option is d.

Note: Another mechanism known as transpiration differs from guttation in many ways. One of which is that transpiration occurs in the day time with the help of stomata, when heat and light is very high in the day time the water content evacuate in the form of water vapors but at the night time the heat and the light is very less than guttation takes place through the margins of the leaves. So the transpiration occurs in the form of vapors and guttation eliminates in the form of liquid.
Transpiration does not occur during the night because stomata are closed but guttation is commonly seen at night and early morning. Plants release excess of water via the guttation. In day time as the transpiration rate increases, excess water is released via transpiration and hence guttation decreases.