Question

Absorption of ions by plant roots along the electrochemical potential is _______

• A. Active absorption
• B. Passive absorption
• C. Diffusion
• D. Root interception

Hint:

Spontaneous transport "along/down" a gradient is always "passive." Non-spontaneous transport "against/up" a gradient requires energy (ATP) and is therefore "active."

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Nutrient uptake by plant roots occurs through active or passive biological mechanisms.
The direction of transport relative to the electrochemical gradient determines whether metabolic energy is required.

Step 2: Detailed Explanation:
Let us evaluate the different ion absorption mechanisms:
Passive Absorption (B): This is the movement of ion species down (along) an electrochemical gradient (from high potential to low potential).
Since the transport is spontaneous and thermodynamically favored, it does not require metabolic energy (ATP) from plant respiration.
Therefore, ion absorption along the electrochemical potential is passive absorption.
Active Absorption (A): This is the transport of ions against (up) an electrochemical gradient, which requires the expenditure of metabolic energy (ATP) via specialized protein pumps or carriers.
Diffusion (C): This is a physical mechanism of solute transport from high to low concentration in soil solution, but does not represent the biological absorption mechanism itself.
Root Interception (D): This is the direct contact between roots and soil particles as roots grow through the soil matrix.

Step 3: Final Answer:
Absorption of ions along the electrochemical potential is passive absorption, which corresponds to option (B).