Question

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R:
Assertion A: Late wood has fewer xylary elements with narrow vessels.
Reason R: Cambium is less active in winters.
In the light of the above statements, choose the correct answer from the options given below:

• A. Both A and R are true but R is NOT the correct explanation of A
• B. A is true but R is false
• C. A is false but R is true
• D. Both A and R are true and R is the correct explanation of A

Answer 1

The Correct Option is D

To determine the most appropriate answer to the given question, we need to examine the relationship between the Assertion (A) and the Reason (R).

• Assertion A: Late wood has fewer xylary elements with narrow vessels.
• Reason R: Cambium is less active in winters.

Explanation:

The process of forming wood involves activity from the vascular cambium. Wood is made up of early wood (also known as springwood) and late wood (also known as summerwood). Early wood generally forms in the growing seasons with more favorable conditions, leading to larger vessel elements. Late wood forms when the cambium is less active, often during colder seasons such as winter, causing the vessels to be narrower.

In the given statements:

• Assertion A states that late wood has fewer xylary elements with narrow vessels.
• Reason R explains that the cambium is less active in winters, which is when late wood generally forms.

Both the Assertion and the Reason are true statements. Moreover, Reason R appropriately explains why Assertion A is true, as the lower activity of cambium in winter results in the formation of late wood with its characteristic narrow vessels.

Thus, the correct answer is: Both A and R are true, and R is the correct explanation of A.

Answer 2

Assertion A is true: Late wood, also known as "summer wood," is the portion of a tree ring that is formed during the later part of the growing season. It typically has fewer xylary (wood-forming) elements and narrower vessels compared to early wood.

Reason R is true and provides the correct explanation for Assertion A: The cambium, a layer of actively dividing cells between the xylem and phloem, is responsible for the formation of new xylem cells. During winters, the cambium becomes less active due to the colder temperatures and reduced metabolic activity. This reduced cambial activity leads to the formation of narrower vessels and fewer xylary elements in the late wood.

So, the correct option is (D): Both A and R are true and R is the correct explanation of A