Question

What do you understand by the process of transpiration? List at least five advantages of transpiration.

Answer 1

Hint: This process is similar to evaporation. However the transpiration process is controlled by structural and physiological adaptations of plants. It is considered as ‘necessary evil’ in the plants.

Complete Answer:
Transpiration is the loss of water in the form of vapours from the aerial parts of the plant.
Based on parts of plants involved in transpiration, there are four types:
1) Stomatal Transpiration:
Stomata are small openings or pores seen on the leaves and stems. If transpiration takes place through these pores, it is Stomatal transpiration. These are responsible for 50-97% of total transpiration.

2) Cuticular Transpiration:
If water is lost directly from the outer walls of epidermis l.e. Through the cuticle, it is Cuticular transpiration. (Cuticle is a wax layer made up of cutin and it covers the epidermis). This constitutes 3-10% of total transpiration.

3) Lenticular Transpiration:
Lenticels are aerating pores in the cork of the woody stems, twigs and fruits. When water is lost through these pores, it is known as lenticular transpiration. It accounts for only 0.1% of total transpiration.

4) Bark transpiration:
This occurs through the bark of woody stems. It is only 1% of total transpiration.

Advantages of Transpiration:
- It is a very important process in plants as it creates a negative pressure gradient that helps to flow water and minerals from the roots to the entire plant.
- It helps to keep the plant cool during hot weather.
- It also helps in exchange of gases.
- It prevents plants from wilting by helping them to maintain cell turgidity
- It plays a major role in water cycle as it releases around 10% of water in the atmosphere
- Transpiration depends on four factors Light, Temperature, Humidity, Wind

Note: As mentioned above the main function of the transpiration process is to supply water to the entire plant body.
- There are three main factors involved in the movement of water in the plants.
- Absorption of water at the roots.
- Capillary action in the xylem.
- Transpiration pulls in the leaves.
- The transpiration pull helps the water to flow against gravity.