Chapter 38, Problem 1TYK

Under what conditions does the rate of transpiration increase?

When the temperature of a leaf decreases

When stomata close at night

During rainstorms, when atmospheric pressure is low

When the weather changes and air becomes drier

Summary Introduction

Introduction:

Transpiration is defined as a process of loss of water molecules by means of evaporation from aerial parts of plants like leaves, stem and flower. Water is essential for the growth and metabolism of the plants, but a small amount of water is utilized by the plants, while most of it (97-99%) is lost in environment by means of transpiration and guttation. The specialized structures responsible for the process of transpiration are named as stomata. These are the pores present numerously in leaves and bordered by the guard cells and stomatal accessory.

Answer to Problem 1TYK

Correct Answer:

The process of transpiration is accompanied under two situations(1) when the stomata are open and (2) when the air of the external environment is drier than the plant’s internal environment.

Explanation of Solution

Explanation/Justification for the correct answer:

Option (d) is the correct answer. Here, it is given that the rate of transpiration is increases when the weather changes and air becomes drier, which is a true statement because the decrease in air humidity leads to an increase in transpiration.

Explanation for the incorrect answers:

Option (a) is given that rate of transpiration is increases when the temperature of leaf decreases, this statement is not true as increase in temperature always leads to an increase in transpiration, to cope up from the adverse effect of heat.

Option (b) is given that rate of transpiration is increases when the stomata close at night, this statement is not true as stomata are the pores responsible for the transpiration, so there is no transpiration when they are closed.

Option (c) is given thatrate of transpiration is increases during rainstorms when the atmospheric pressure is low, this statement is not true as rainstorms leads to an wet external environment with higher humidity, so condition is feasible for less transpiration.

Hence option (a), (b) and (c) are incorrect.

Conclusion

The rate of transpiration is depends upon many climatic factors, one important factor is air humidity so when the externa air is drier, the rate of transpiration is increases.