Question

Companion cells are closely associated with which of the following options?
A. Sieve elements
B. Vessel elements
C. Trichomes
D. Guard cells

Answer 1

Hint: Companion cells are cells which are found in flowering plants adjacent to the sieve tube in the phloem and help in regulation of flow of the nutrients. These cells are parenchymal cells.

Complete answer:
If we talk about plant tissues it consists of mainly xylem and phloem tissues. Xylem tissues are responsible for transportation of water and minerals from roots to the other parts of the plant body from soil. Whereas, phloem are the cells responsible for transportation of food material that is glucose or other sugars synthesised in leaf after photosynthesis.
Phloem tissues consist of three types of cells that are conducting cells, parenchyma cells and supporting cells. Conducting cells in phloem tissues are sieve tubes which are responsible for transport of sugar from leaves to different parts of plants.
Companion cells are one of the parenchyma cells of phloem tissues. The role of these sieve tubes is dependent on companion cells as all the functions of sieve tubes are performed by these companion cells. These sieve tubes are connected to the companion cells through the cytoplasm of the companion cells. Plasmodesmata is also present in-between these sieve cells and companion cells.
If we look at given options, the sieve system we had already discussed. Option ’B’ is a vessel system which consists of xylem and phloem and we had talked about it above. Option ‘C’ is trichomes are small hair-like structures which outgrow plants on plants, algae, lichens and many protists. Option ‘D’ is guard cells which are cells around the stomata.

So, after this discussion we can conclude that sieve elements are the cells which are connected most closely with the companion cells.

Note:
Companion cells work with sieve tubes or sieve systems and also structurally both present in the surroundings of each other. So, we can say companion cells are most closely related to sieve tissues.