Question

The functional plant cells that lack a nucleus

• A. xylem parenchyma
• B. sieve tube cells only
• C. both companion and parenchyma cells
• D. both tracheids and sieve tube cells

Answer 1

The correct option is D both tracheids and sieve tube cells

Xylem functions as a conducting tissue for water and minerals from roots to the stem and leaves. It also provides mechanical strength to the plant parts. It is composed of four different kinds of elements, namely, tracheids, vessels, xylem fibres and xylem parenchyma. Tracheids, vessels and fibres are dead cells and lack nucleus. Xylem parenchyma are the only living cells in xylem tissue and have nucleus.

Phloem is a food conducting tissue. It is made up of four elements - sieve tube elements, companion cells, phloem parenchyma and phloem fibres.
Sieve tube elements, companion cells, phloem parenchyma are living cells and phloem fibres are dead. Sieve tube cells are the only living plant cells without a nucleus. The activities of sieve tube cells are controlled by companion cells.