Concept: This question tests your understanding of leaf morphology, specifically the structure of the leaf base and the primary function of leaves.

Why (C) is correct:

The Assertion states that a swollen leaf base is called a pulvinus, which is true. A pulvinus is a characteristic feature of many leguminous plants and is involved in sleep movements (nyctinasty) and touch-induced movements (thigmonasty).

The Reason states that pulvinus are the most important vegetative organs for photosynthesis. This is false. The primary site for photosynthesis in most plants is the leaf blade (lamina), not the pulvinus. The pulvinus is primarily involved in movement.

Why other options are wrong:

• (A) Incorrect because the Reason is false.
• (B) Incorrect because the Reason is false.
• (D) Incorrect because the Assertion is true.

Common Mistake: Students might confuse the function of different parts of the leaf. While the entire leaf is a photosynthetic organ, the pulvinus itself is specialized for movement, not photosynthesis.

NEET Tip: Remember that the pulvinus is a specialized structure at the base of the petiole, often found in legumes, responsible for turgor-driven movements. Photosynthesis primarily occurs in the lamina due to the presence of chloroplasts.

Correct Answer: (C)