Test: Transpiration (Old NCERT) - Grade 12 MCQ

In some grasses (isobilateral leaves), on epidermis, there are some larger, thin walled cells called bulliform cells are present, which in dry condition lose water through transpiration and thus the rolling up of leaves occurs, e.g., in Poa, Agropyron, Amophilla, etc.

(A) Vein ending - Guttation
(B) Necessary evil - Transpiration
(C) Semi-permeable membrane - Osmosis
(D) Cohesion - Transpiration pull
(E) Stomata closure - ABA
So, the correct answer is (b).

When water supply is adequate, guard cells become turgid, their thin walls get extended and thick walls become slightly concave so that the stomatal aperture opens as shown in figure, condition (i).

Leaf having stomata equally distributed on both surfaces is called amphistomatic (isobilateral) leaf, e.g., most monocot leaves.

The loss of water in the vapour form from the exposed parts of a plant is called transpiration the loss of water due to transpiration is quite high. It is 2 litres per day in sunflower 36 − 45 litres in apple and upto 1 tonne per day in elm tree.