Question

Why are perforated walls present in sieve tubes which is a part of phloem?

Answer 1

Sieve tubes:

Sieve tubes act as the conducting structure of the phloem. Phloem is responsible for the transport of organic molecules to the different parts of the plant. Therefore, the molecules from the phloem can move in both directions.

There are perforations present between the walls of the sieve tube or the sieve plate. It helps with the movement of organic molecules through the cells of the sieve tube. The cells need these perforations to allow the movement of these molecules as the process is not similar to the movement of water through the xylem.