Question

The droplets of water arranged at the edges of the leaves of the roses in the morning are
A) Water drops condensed from the atmosphere during night at low temperatures
B) Water transpired from the stomata and the lenticels
C) Water produced on the leaves from the reaction of hydrogen and atmospheric oxygen
D) None of the above

Answer 1

Hint: The leaves are the parts of the plant through which exchange of gaseous and water vapour takes place during the day time. It contains chlorophyll which is the photosynthetic pigment of the plant. The photosynthesis takes place during the day and stops at night.

Complete answer:
To answer this question, we must know about the process of loss of water through leaves in plants.

The transpiration is a process by which the water is lost in the form of water vapour through the aerial parts of the plant. The transpiration takes place through stomata which are the minute pores on the surface of the leaves. These pores are open during the day time and closed at night.

The transpiration creates a transpirational pull due to which the water exits from the leaves. At night due to the closure of stomata, the water cannot be released but the transpirational pull is still there. In the morning the stomata opens. Hence these forces tend the water to be released in the form of droplets.

The water condensed from the atmosphere is known as dew drops. These drops will evenly spread on the leaf surface. So option A is incorrect.

The water produced in the atmosphere from the reaction of hydrogen and oxygen is in the form of water. (option C is incorrect)

Thus the correct answer is option ‘B’.

Note: Lenticels are present on the barks of a woody tree. They are openings present on the surface of the stem through which gaseous exchange and water is evaporated. Unlike stomata, lenticels do not have guard cells. So they are open throughout the day and night.