Question

Which of the following is used to determine the rate of transpiration in plants?
A. Porometer
B. Potometer
C. Auxanometer
D. Tensiometer

Answer 1

Hint: The transpiration is one of the important activities happening in plants. It enables cells to maintain their turgidity and also helps plants to maintain constant osmotic pressure which assists water transportation from roots to all other body parts of plants.

Step by step answer:Transpiration is a process by which plants lose water in the form of water vapors. There are specialized pores present in leaves called stomata. These stomata play an important role in the process of transpiration. They possess two cells regulating their closing and opening which are termed as guard cells. The rate of transpiration depends on various physical factors like the availability of water for the plants, temperature, humidity, etc. The plants whose habitat is dry, and hot, usually have small leaves to reduce the area of transpiration and save water from getting evaporated. Such adaptations are seen in plants in desserts living with low amounts of water. The plants whose habitat is cold and who live in more humid places, tend to have larger leaves having more stomatal openings allowing faster transpiration. Potometer is the instrument used to measure the rate of transpiration. The basic photometer has the plant whose transpiration is to be measured connected to a capillary tube. The rate is measured by measuring the time needed for the bubble in the tube to cover a certain fixed distance. The rate at which water is taken by plants usually gives an idea about its transpiration rate.
Thus the correct answer is option B. Potometer
Additional information: The transpiration is very important for maintaining the water pull across the length of the plant as when the water is lost through transpiration, roots are induced to absorb water from the soil. This pressure enables xylem tissues to carry water in the direction which is opposed to gravity through roots.

Note: the reading by potometer is not reliable. As it measures the quantity of water absorbed by plants. But all of the water taken up by plants need not be necessarily used for transpiration. The cell might use the water in the process of photosynthesis or simply retain water to maintain turgidity. So to be precise, a potometer actually measures the rate of uptake of water by the plant and not the rate of transpiration.