This set of Engineering Hydrology Multiple Choice Questions & Answers (MCQs) focuses on “Transpiration”.
1. Which of the following is true regarding transpiration process?
a) Continuous and constant rate
b) Continuous and varying rate
c) Intermittent and constant rate
d) Intermittent and varying rate
View Answer
Explanation: Unlike evaporation, transpiration is not a continuous process and takes place only during sunlight hours. The rate of transpiration varies and also depends upon the growth period of the plant.
2. If the atmosphere suddenly becomes dry, how does the rate of transpiration change?
a) Increases
b) Decreases
c) Remains unchanged
d) The change cannot be predicted
View Answer
Explanation: When the relative humidity of the atmosphere suddenly decreases (becomes dry), the rate of transpiration should increase. This is because the air will not be saturated with moisture and there will be less hinderance to the water vapour transpired from the plant.
3. In which of the following cases will the transpiration rate be higher?
Case 1: A slight breeze is blowing.
Case 2: Strong and violent winds in multiple directions.
a) Case 1
b) Case 2
c) Cannot be determined
d) Same in both cases
View Answer
Explanation: A normal wind helps in the transpiration process as it carries the collected vapour away from the plant. In case of aggressive winds, the transpiration decreases as it may close the stomata and also cause hindrance to the outward movement of the water vapour from the plant.
4. Which of the following external changes cause the rate of transpiration to decrease?
a) Increase in temperature
b) Increase in sunlight
c) Increase of available soil water
d) Increase of carbon dioxide concentration
View Answer
Explanation: Increase in temperature, sunlight and soil water help in increasing the rate of transpiration from a plant. However, an increase in carbon dioxide concentration causes the stomata to close and retards the transpiration process.
5. During transpiration, the water can be lost only from the stomata.
a) True
b) False
View Answer
Explanation: The majority of the transpiration process takes place through the stomata. However, around 5 to 10% of the transpiration takes place through the cuticles and lenticels.
6. Which of the following is a not an advantage of transpiration for the plant?
a) Movement of water
b) Translocation of mineral salts
c) Seasonal loss of leaves
d) Regulation of plant temperature
View Answer
Explanation: Transpiration is considered to be a necessary evil by some people. Even though it has few advantages, it also leads to the water deficiency within plants, affects metabolic processes and leads to shedding of leaves to control the loss of water.
Sanfoundry Global Education & Learning Series – Engineering Hydrology.
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