Q1. [1] § 5.4 TRANSPORTATION § 5.5 EXCRETION
Assertion (A) : The basic filtration unit in the kidneys, like in the lungs, is a cluster of very thin-walled blood capillaries.
Reason (R) : Each capillary cluster in the kidney is associated with the cup-shaped end of a coiled tube called Bowman's capsule.
- (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
- (C) Assertion (A) is true, but Reason (R) is false.
- (D) Assertion (A) is false, but Reason (R) is true.
Previously asked in CBSE board exam
2026 31/3/1 Q9
Generated by claude-sonnet-4-6 · 2026-06-11 09:52 · grounding rag
Model Answer
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
Both statements are factually correct, but R describes what Bowman's capsule is — it does not explain why the filtration unit is a capillary cluster.
Explanation
The Assertion is directly from the textbook: "the basic filtration unit in the kidneys, like in the lungs, is a cluster of very thin-walled blood capillaries." The Reason is also correct: "Each capillary cluster in the kidney is associated with the cup-shaped end of a coiled tube called Bowman's capsule." However, R merely names/describes the structure associated with the capillary cluster; it does not explain the assertion about capillaries being the filtration unit. Hence option (B) is correct.
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