Question

Plasmodesmata are usually observed between

• A. Sieve tubes and bast fibres
• B. Tracheae and phloem fibres
• C. Xylem parenchyma and xylem fibres
• D. Sieve tubes and companion cells

Hint:

\[ \boxed{ \text{Sieve tube elements } \longleftrightarrow \text{Companion cells} } \] are connected by numerous plasmodesmata for efficient transport in phloem.

Answer 1

The Correct Option is D

Step 1: Recall the function of plasmodesmata. Plasmodesmata are cytoplasmic connections between adjacent living plant cells. They facilitate the movement of nutrients and signaling molecules.

Step 2: Identify the correct pair. Sieve tube elements lack a nucleus and depend on companion cells for metabolic activities. They are connected through numerous \[ \boxed{\text{plasmodesmata}.} \]

Step 3: Choose the correct option. Hence, plasmodesmata are usually observed between \[ \boxed{\text{Sieve tubes and companion cells}.} \] Therefore, the correct option is \[ \boxed{(D).} \]