Question

Assertion (A): Facilitated diffusion is very specific, it allows cell to select substance for uptake.
Reason (R): Facilitated diffusion is sensitive to inhibitors which react with protein side chain.

• A. Both (A) and (R) are correct and (R) is the correct explanation to (A)
• B. Both (A) and (R) are correct but (R) is not correct explanation for (A)
• C. (A) is correct (R) is wrong
• D. (A) is wrong (R) is correct

Hint:

Any transport process that relies on membrane proteins (facilitated diffusion and active transport) will be highly specific, saturable, and sensitive to inhibitors.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question presents an Assertion regarding the selectivity of facilitated diffusion and a Reason explaining its sensitivity to chemical inhibitors.

Step 2: Key Concepts and Approach:
We evaluate the transport mechanism of facilitated diffusion, which relies on specific transport proteins embedded in the cell membrane.
We analyze how the protein structure governs both substrate specificity and inhibitor sensitivity.

Step 3: Detailed Explanation:

• Assertion (A): Facilitated diffusion is highly selective because transport depends on specialized carrier or channel proteins.
These proteins only allow specific molecules with matching shapes to cross the membrane. This high specificity allows the cell to regulate solute uptake, making Assertion (A) correct.

• Reason (R): Transport proteins have active sites made of amino acid chains with reactive side groups.
Inhibitors can bind to these side chains, altering the protein's conformation and blocking transport.
This sensitivity to inhibitors demonstrates that the transport is mediated by specific proteins, explaining why facilitated diffusion is highly specific.
Therefore, Reason (R) is correct and explains Assertion (A).


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