Question

The living component of xylem tissue is?
a. Xylem vessel
b. Xylem parenchyma
c. Xylem tracheid
d. Xylem fibre

Answer 1

Hint: Xylem tissue is made up of four types of cells i.e., xylem parenchyma cells, xylem fibre cells, vessels, and tracheids. Characteristics of a living plant cell include the presence of a prominent nucleus, thin cell walls, vacuoles, and protoplasts.

Complete answer:
> Option (A) is incorrect. Each xylem vessel is formed by the union of short, wide, lignified dead cells. These cells are devoid of nucleus and cytoplasm. The end walls of these cells are completely broken to form a channel that will help in the transport of water and other soluble nutrients.

> Option (B) is correct. Xylem parenchyma is composed of parenchymatous cells that are the only living cells in the xylem tissue because of the presence of a prominent nucleus, large vacuoles, thin cell walls, and protoplasts. These cells are involved in the storage of carbohydrates, oils, and other substances.

> Option (C) is incorrect. Xylem tracheid consists of elongated dead cells that are tapering at the ends and have thick cell walls. Pits are present in tracheids through which water is transported from one tracheid to the other.

> Option (D) is incorrect. Xylem fibre is made up of dead sclerenchymatous cells that lose their protoplasts at maturity. They are present in between the vessels and tracheids and their great tensile strength provides mechanical support to the water-conducting tissues of the xylem.

Hence, the correct answer is option (B).

Note: Xylem tissue is present in all vascular plants and it helps in the transport of water and soluble nutrients from the roots to different parts of the plants. Xylem parenchyma is the living component of the xylem tissue while the tracheids, vessels, and xylem fibres form the dead component of xylem tissue due to the absence of nucleus and cytoplasm.