Question

Assertion (A): The functions of sieve tubes are controlled by the nucleus of companion cells. The companion cells help in maintaining the pressure gradient in sieve tubes.
Reason (R): Gymnosperms phloem has albuminous cells and sieve cells.
Identify the correct option from the following:

• A. Both (A) and (R) are true. (R) is correct explanation for (A)
• B. Both (A) and (R) are true. But (R) is not correct explanation for (A)
• C. (A) is true, but (R) is false
• D. (A) is false, but (R) is true

Hint:

While solving assertion-reason questions, watch out for statements referring to different groups like angiosperms and gymnosperms — they may both be true but unrelated.

Answer 1

The Correct Option is B

Step 1: Analyze Assertion (A)
Sieve tubes in angiosperms lack nuclei, and their functions are controlled by companion cells which maintain the pressure gradient — so this assertion is true. Step 2: Analyze Reason (R)
In gymnosperms, the phloem lacks sieve tubes and companion cells, instead having sieve cells and albuminous cells. Hence, this reason is also true. Step 3: Examine the explanation relationship
Although both statements are true independently, (R) explains a characteristic of gymnosperms, while (A) is about angiosperms. So, (R) is not the correct explanation for (A).