Question

A mature sieve tube is different from a vessel in

• A. Lacking a functional nucleus
• B. Absence of lignin in walls
• C. Being dead
• D. Lacking cytoplasm

Answer 1

The correct option is B Absence of lignin in walls

A mature sieve tube is different from a vessel in absence of lignin in walls. The main function of the sieve tube is transport of carbohydrates, primarily sucrose, in the plant. Unlike the water-conducting xylem vessel elements that are dead when mature, sieve elements are living cells. They are unique in lacking a nucleus at maturity.
Thus, the correct answer is option B.