Question

Plant lose most of water through leaves by
A. Respiration
B. Guttation
C. Photosynthesis
D. Transpiration

Answer 1

Hint: Water is required for plants but it is not required in excess as roots take up only a small amount for water for growth and metabolism and thus a process involves the excess water loss from leaves.

Complete answer:
> Option A is Respiration. It is a process which provides oxygen from the outside environment to cells within the tissues and moves carbon dioxide out of the body in the opposite direction. Therefore, this cannot be the correct option as it is not a process of water loss through leaves. So, it gets eliminated.

> Option B is Guttation. It is a process where there is secretion of water droplets from the pores (hydathodes) of some vascular plants and this process happens at night when the soil is very moist and the roots absorb water too. This is not the correct option because in this process there is secretion of water in the form of droplets of xylem sap on the tips of leaves but not the water lost through leaves. So, this option gets eliminated.

> Option C is Photosynthesis. It is a process by which green plants make their food by using sunlight or light energy to convert the carbon dioxide and water into glucose and oxygen. It is not a process of water loss through leaves, therefore it cannot be the correct option and gets eliminated.

> Option D is Transpiration. Transpiration is the process of removal of excess water from the stomata present on the leaves and its evaporation too through aerial parts like leaves, stems and flowers. Water is necessary for plants but it is necessary to remove the excess water too as only a small amount of water is taken up by the roots used for growth and metabolism. Therefore, this option is the correct one.

Hence, the correct answer is option (D).

Note: There can be confusion between guttation and transpiration but both are different processes. In guttation, there is secretion of water in the form of droplets from the hydathodes but in the process of transpiration, there is water loss from the stomata present on the leaves and this water gets evaporated.