Question

Which of the following statement(s) regarding the companion cell is/are incorrect?
I. These are closely associated with vessels.
II. They help in loading sugar into the phloem.
III. They help in maintaining the pressure gradient in tracheids.

• A. Only I
• B. Only II
• C. I and III
• D. I, II and III

Answer 1

The correct option is C I and III

Companion cells are found within the phloem of flowering plants. Each companion cell is usually closely associated with a sieve element and remain connected with sieve cells by plasmodesmata. They assist in loading phloem sieve cells with sugars through active transport—the companion cells aid in controlling the pressure gradient in the sieve tubes.

Xylem consists of tracheids, vessels, xylem parenchyma, and xylem fibers. Tracheids have thick lignified walls and are dead or without protoplasm. Each vessel consists of short and broad lignified dead cells joined end to end, forming a tubular structure. Both tracheids and vessels help in the conduction of water in a plant.