“Transpiration is a necessary evil”. Explain.

Hint: Transpiration is a biological process by which water is lost from plants in the form of water vapour through tiny pores present in the leaves and other aerial parts of the plant.

Complete Answer:
- Transpiration is the process in which there is a loss of water in the form of water vapour from the stomatal openings. It is beneficial to the plants due to its role in the ascent of sap, absorption and translocation of mineral salts, and in the regulation of the temperature of plant tissues.
- Transpiration creates a pull for absorption and translocation of water as well as minerals. Photosynthesis rate, which is limited by the available amount of water, and it slowly gets transpired. Transpiration and photosynthesis occur simultaneously due to the opening of stomata.
- However, transpiration also causes loss of water unnecessarily. Due to the process of transpiration, there is pressure on the plant for the absorption of water. Therefore, the process of transpiration is called a necessary evil.

Some of the important functions of transpiration in plants are:
- It helps in the maintenance of cell turgidity and it also helps in cell division.
- It helps in the maintenance of water within the plant as water is eliminated from the plant continuously.
- The cooling effect of the tree is because of transpiration.
- It cools down the surface of the leaves.
- It also helps in growth and development.
- It regulates the temperature of the plants.
- It allows the movement of water and minerals from the soil to different parts of the plant.

Note: There are a few drawbacks of transpiration, they are,
- A huge amount of energy is used/ released during the process of transpiration.
- The process of transpiration is slowed down if the water absorbed by the root is not sufficient.
- It can lead to excess loss of water in the case of xerophytes.