Question

Companion cells are associated with
A. Axial parenchyma
B. Ray parenchyma
C. Sieve tubes
D. Sclerenchyma

Answer 1

Companion cell is a type of cell which is present within the phloem of flowering plants. They are nucleated cells and bear many mitochondria. These cells mainly function as the regulator of the flow of nutrients. They are one type of parenchymal cell.

Complete answer:
Plants consist of mainly two types of tissue, which are xylem and phloem tissue. Xylem tissue consists of tracheary elements, xylem parenchyma cells, and xylem fibre cells. Tracheary elements are dead. Xylem tissue transports water and nutrients from the root throughout the plant body. Xylem fibre possesses a thickened secondary cell wall that provides mechanical support to the plant body.
Phloem tissue is a type of vascular tissue that completes the function of displacement photosynthate materials from the photosynthetic plant organs to various parts of the plant. The phloem is made up of the four major components that are sieve element, companion cell, phloem sclerenchyma, and phloem parenchyma.
The companion cells are a type of specialized parenchyma cells that present in the phloem tissues of the angiosperms. They are a type of nucleated living cells which contain several ribosomes, plastids, and mitochondria. The nuclei and nucleoli of the companion cells are relatively large for that they are more metabolically active.
The companion cells have close contact with the sieve tube elements. The function of this sieve tube is fully dependent on the companion cell because the companion cells perform the function of regulating the activity of the adjacent sieve elements. The sieve tubes connect to the companion cell through the cytoplasmic connections as well as the plasmodesmata which are also present between the two cells. These cells supply energy to the sieve elements during food translocation.
A companion cell and the associated sieve element are associated in a developmental relationship, which means that they arose from a common progenitor cell. Generally, there are two types of companion cells found, one is the ordinary companion cells and the other is the transfer cells. Companion cells can be seen only in angiosperms.

Therefore, the correct option is option C.

Note: Companion cells are present in the phloem tissue of the flowering plant. This tissue is a special type of parenchyma cells. These cells are closely associated with the sieve tubes. They are connected via cytoplasm of companion cells and plasmodesmata. They produce energy during food transport and help in the regulation of the sieve cells.