Read the following statements regarding bulliform cells in plant leaves: I. They are modified abaxial epidermal cells. II. They are large, empty and colourless cells. III. When they are turgid, they make the leaves curl inwards to minimise water loss. IV. They are characteristically found in grasses. Choose the correct combination of statements:

Step-by-step solution

According to NCERT, in grasses, certain adaxial (upper) epidermal cells along the veins modify themselves into large, empty, colourless cells called bulliform cells. Therefore, statement I is incorrect because they are adaxial, not abaxial. Statement II is correct as it accurately describes their structure. When bulliform cells absorb water and become turgid, the leaf surface is exposed. It is when they become flaccid due to water stress that they cause the leaves to curl inwards to minimise water loss. Thus, state