Question

Assertion (A): Due to the differences in the activity of the cambial ring the amount of secondary xylem is more than secondary phloem in dicot stem. Reason (R): The cambium forms a narrow band of parenchyma which passes through secondary tissues in the radial direction is called secondary medullary ray.

• A. Both (A) and (R) are correct and (R) is the correct explanation to (A)
• B. Both (A) and (R) are correct but (R) is not correct explanation for (A)
• C. (A) is correct (R) is wrong
• D. (A) is wrong (R) is correct

Hint:

The vascular cambium activity is unequal, leading to the formation of wood (secondary xylem).

Answer 1

The Correct Option is B

Step 1: Read the Assertion.
The Assertion says that in a dicot stem, more secondary xylem is made than secondary phloem because the cambial ring works unevenly.

Step 2: Check the Assertion.
This is true. The vascular cambium is more active on its inner side, so it cuts off more xylem inward than phloem outward. So the Assertion is correct.

Step 3: Read the Reason.
The Reason describes the cambium forming a narrow band of parenchyma that runs sideways through the secondary tissues, called a secondary medullary ray.

Step 4: Check the Reason.
This is also a true statement, because secondary medullary rays really are radial bands of parenchyma made by the cambium. So the Reason is correct.

Step 5: See if Reason explains Assertion.
The Assertion is about why more xylem than phloem forms, but the Reason only describes medullary rays. The Reason does not explain the uneven xylem-phloem amount.

Step 6: Conclude.
Both statements are correct, but the Reason is not the correct explanation for the Assertion.
\[ \boxed{\text{Both (A) and (R) are correct but (R) is not correct explanation for (A)}} \]