Question

Assertion: Long distance flow of photoassimilates in plants occurs through sieve tubes.

Reason:  A mature sieve tube has peripheral layer of cytoplasm without any nucleus.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

Answer 1

The correct option is: (b)

Explanation:

The main function of sieve tube is the transport of food products from green and storage organs of the plant to other organs of the plant. The sieve elements are sieve tubes arranged one above the other and have sieve plates (oblique or transverse perforated septa) on their end walls. The cytoplasm occur in the form of a thin living layer along the inner side of cellulose wall. The nucleus disappears in mature sieve elements.