Question

Why is transpiration important for plants?
a. It provides essential $CO_2$ needed for photosynthesis.
b. It helps in absorption and upward movement of water and minerals.
c. It prevents the plant from heating up.
d. Both B and C.

Answer 1

Hint: Transpiration helps in cooling of the surface of leaves due to the evaporation. It can take place through stomata, leaves, lenticels and barks also transpiration is absent in submerged aquatic plants and algae.

Complete answer:
Transpiration is the process of water loss in the form of vapours from the aerial parts of the plants. According to Curtis, “transpiration is the necessary evil”. According to Stewards, “transpiration is the unavoidable evil.”

Transpiration can be of 3 types
> Stomatal Transpiration: Transpiration takes place through stomata.
Stomata are the minute pores present on the epidermis of leaves, responsible for water loss and gaseous exchange.
About 80-90% of transpiration occurs through stomata.

> Cuticular Transpiration: Transpiration takes place through the cuticle.
Cuticle is a thin layer present over the epidermis.
About 9% of transpiration occurs through the cuticle.

> Lenticular transpiration: Transpiration takes place through lenticels.
Lenticels are the minute pores found on the stem of woody plants and epidermis of fruits.
About 1% of transpiration occurs through lenticels.

The significance of transpiration are-
- It helps in cooling of plants due to evaporation from leaves.
- It helps in the conduction of water and minerals due to the development of transpiration pull in the plant.
- It also helps in maintenance of turgidity in the plant cell.
- It supplies water to the leaves for the process of photosynthesis.
- It helps in water absorption through roots.

Hence, The correct answer is option (D).

Note: Transpiration pull is the process which works against the direction of gravity in plants. It is responsible for upward movement of water and minerals in different parts of plants through xylem channels.