Question

Which type of mineral absorption shows a sudden drop when the roots are deprived of oxygen?

• A. Passive absorption by direct ion-exchange.
• B. Passive absorption by mass flow.
• C. Donnan equilibrium.
• D. Active Absorption.

Hint:

Active absorption needs ATP from aerobic respiration, so it falls when oxygen is absent.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
Mineral absorption by roots can be passive (no energy) or active (needs metabolic energy).

Step 2: Active absorption
Active absorption carries ions into root cells against the concentration gradient through carrier proteins, using ATP.
The ATP comes from aerobic respiration, so without oxygen the ATP supply drops and uptake falls sharply.

Step 3: Passive processes
Ion exchange, mass flow and Donnan equilibrium are physical processes and do not need metabolic energy.

Final Answer:
Active absorption drops suddenly when roots lack oxygen. \[ \boxed{\text{(D) }\text{Active Absorption.}} \]