Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Ascending limb of loop of Henle is impermeable to water and allows transport of electrolytes actively or passively. Reason (R) : Dilution of filtrate takes place due to efflux of electrolytes in the medullary fluid. In the light of the above statements, choose the correct answer from the options given below :
Answer: (B) Both (A) and (R) are true but (R) is not the correct explanation of (A). Answer: (B) Both (A) and (R) are true but (R) is not the correct explanation of (A).
- 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
Correct Answer
(B) Both (A) and (R) are true but (R) is not the correct explanation of (A)
Solution & Explanation
Answer: (B) Both (A) and (R) are true but (R) is not the correct explanation of (A). Solution: Assertion is TRUE — NCERT states the ascending limb of the loop of Henle is impermeable to water but allows transport of electrolytes actively or passively. Reason is also TRUE — the filtrate gets diluted due to the passage (efflux) of electrolytes into the medullary fluid. However, R describes the CONSEQUENCE (dilution of the filtrate) of the electrolyte transport, not the cause of why the ascending limb is impermeable to water; therefore R does not correctly explain A. NCERT Reference: Ch 16, p.209, lines 41-43 — "The ascending limb is impermeable to water but allows transport of electrolytes actively or passively. ... filtrate gets diluted due to the passage of electrolytes to the medullary fluid."