Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Mobility is the overall process where by nutrients reach the root surface and sorption into plant.
Reason (R) : Mobility involves the solution or exchange of nutrients and movement to root surface.
In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

To understand nutrient mobility, remember that nutrients must first enter the soil solution phase (via dissolution or exchange) before they can travel to the root surface via mass flow or diffusion for uptake.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Nutrient mobility in soil describes how nutrient ions move through the complex soil-water-air matrix to reach the rhizosphere, making them available for root uptake.

Step 3: Detailed Explanation:
Let us analyze the Assertion and the Reason:
- Assertion (A) is true: Soil nutrient mobility is defined comprehensively as the overall process by which nutrients move from the solid soil phase or bulk soil solution, travel across the rhizosphere, arrive at the active root surface, and are subsequently absorbed (sorbed) across the root cell membranes into the plant.
- Reason (R) is true: This physical mobility is driven by specific chemical and transport mechanisms.
First, nutrients must dissolve into the soil solution or undergo ion exchange off clay and organic surfaces.
Once in the liquid phase, they move to the root surface via three primary pathways: mass flow (driven by transpiration), diffusion (driven by concentration gradients), and root interception (direct physical contact).
- Analysis of Explanation: The Reason describes the exact chemical and physical steps (solution/exchange and transport pathways) that constitute the overall nutrient mobility and sorption process defined in the Assertion. Hence, the Reason is the correct explanation of the Assertion.
Therefore, Both (A) and (R) are true, and (R) is the correct explanation of (A).

Step 4: Final Answer:
Both (A) and (R) are true, and (R) is the correct explanation of (A).