Question

What are the control points where a plant adjusts the quantity and types of solutes that reach the xylem ?

• A. Transport proteins of endodermal cells
• B. Sclerenchyma around the pericycle
• C. Suberin deposited casparian strips
• D. The root hairs themselves

Answer 1

The correct option is A Transport proteins of endodermal cells

Endodermal cells in roots have transport proteins that are control points, where a plant can adjust the quantity and types of solutes that reach the xylem.

Endodermis (called starch sheath in dicot stem). It is mostly single layered and is made up of parenchymatous, barrel shaped, compactly arranged cells. The inner and radial wall of root endodermis cells have casparian strips. These thick walled endodermal cells are interrupted by thin walled cells just outside the protoxylem patches. These thin walled endodermal cells are called passage cells.

Endodermis behaves as water and air tight dam to check the loss of water and entry of air in xylem elements.
Hence, option B is correct.