Question

Which one of the following given below, does not have perforated wall?
A.Tracheids
B.Companion cells
C.Sieve tubes
D.None of these

Answer 1

Hint: Cell wall is a tough, flexible sometimes rigid structural layer that surrounds some types of cells(Outside the cell membrane). The perforated cell wall has a cell with holes in it. End walls of xylem and phloem are modified into perforation plates, where there is no shared wall material available in some angiosperm plants.

Complete answer:
Xylem element contains tracheid and vessels which helps in the conduction of water. They are long-tube like structures. Their walls are partially or completely dissolved walls to form pipes in vessels and pits for conducting water in tracheids. The adjacent cells can communicate or exchange fluid through the pit, as they are relatively thinner.

Sieve tubes and companion cells-they are part of phloem. Companion cells provide necessary proteins to sieve tubes as they don't have a nucleus or ribosomes for signaling ATP or to transfer the molecules. With the help of plasmodesmata connections, they are associated with the sieve tubes. Plasmodesmata connections are the connections of the cytoplasm of the neighboring cell to molecules. So, plasmodesmata means pores present in the cell wall.
But Tracheid has pits in their cell but not the pores. Perforated cell walls are absent in tracheids.

Hence the correct answer is OPTION(A)

Note: The water-conducting and mechanical supporting cells of gymnosperms are tracheids. They transport water longitudinally through endplates and laterally through pits. It is the defining characteristic of vascular plants from nonvascular plants. When transpiration is not occurring, they serve to hold water against gravity(cohesion).