Question: 91. 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 :
(1) \mathbf{A} is true but \mathbf{R} is false.
(2) \mathbf{A} is false but \mathbf{R} is true.
(3) Both \mathbf{A} and \mathbf{R} are true and R is the correct explanation of \mathbf{A}.
(4) Both \mathbf{A} and \mathbf{R} are true but \mathbf{R} is NOT the correct explanation of \mathbf{A}.
Answer: Option (3)
Explanation:
Late wood is formed during unfavorable seasons such as winter,
when environmental conditions like temperature and water availability are not suitable for active growth.
During winter, the vascular cambium becomes less active, resulting in reduced cell division.
Because of this reduced cambial activity, fewer xylary elements are produced.
The xylem cells formed during this period have narrow vessels and thick cell walls,
which is a characteristic feature of late wood.
Thus, Assertion A is true.
Reason R correctly states that cambium is less active in winters.
Since reduced cambial activity directly leads to the formation of late wood with
fewer xylary elements and narrow vessels, Reason R correctly explains Assertion A.