Question

Assertion : Ions are absorbed from the soil by active transport only.
Reason : The proteins present in the membranes of root hair cells passively pump ions from the soil into the cytoplasm of the epidermal cells.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (D)

Minerals are present in the soil in the form of ions. Ions cannot directly cross the cell membrane. Ions are absorbed from the soil by both passive and active (majorly) transport. Specific proteins in the membranes of root hair cells actively pump ions from the soil into the cytoplasm of the epidermal cells. Like all cells, the endodermal cells have many transport proteins embedded in their plasma membrane; they let some solutes cross the membrane, but not others. Transport proteins of endodermal cells are control points, where a plant adjusts the quantity and types of solutes that reach the xylem.