Question

Living cells of xylem are
A. Parenchyma
B. Fibers
C. Vessels
D. Tracheids

Answer 1

Hint: There are two types of transport tissue in vascular plants, one is xylem, and the other is the phloem. Main function of xylem is the transportation of water and nutrients from roots to stems and leaves. The main components of xylem tissues include xylem parenchyma, xylem fibers, tracheids, and xylem vessels. The parenchyma cells have differing shapes but usually they are cylindrical and lobed in form.

Complete answer:
Parenchyma: The xylem parenchyma is made up of parenchyma cells. The only living cells in xylem are the Parenchyma cells. Xylem parenchyma is composed of thin cell walls, large vacuoles, prominent nucleus, and protoplasts. The main function of parenchyma cells of xylem is the storage of carbohydrate, fats and water conduction.
Hence option A is the correct answer.
Fibers: These are non-living sclerenchyma cells which lose their protoplast at the time of maturity. Xylem fibers are found in between tracheids and xylem vessels of the xylem tissue. The xylem fibers are former parenchyma cells that developed secondary cell walls. The cell walls of fibers become lignified. They are non-living cells;
Hence, option B is not correct.
Vessels: The long tubes which help in the transportation of water and provide mechanical support are known as xylem vessels. Each of the xylem vessels are formed by the end-to-end union of a large number of wide, short and lignified dead cells. Both the nucleus and cytoplasm are absent in these cells.
Hence option C is also not correct.
Tracheids: The elongated cells of xylem in vascular plants which function to transport water and mineral salts are known as Tracheids. These are one of two types of tracheary elements, in which the vessel elements are the other. Unlike vessel elements, Tracheids do not have perforation plates.
Hence option D is also not correct.

Hence, Option A. Parenchyma is the correct answer

Note:
Axial parenchyma cells and Radial parenchyma cells are two major types of parenchyma cells in secondary xylem. The cell wall of parenchyma is cellulosic and thin. Parenchyma cells are found in both primary and secondary xylem transport tissues. Chloroplasts occur in xylem parenchyma cells in both herbaceous plants and young twigs of woody plants, particularly in ray parenchyma cells.