Q1. [1] § 7.1 DO ORGANISMS CREATE EXACT COPIES OF THEMSELVES? § 7.2.1 Fission
Assertion (A) : When a bacterium divides into two, and the resultant two bacteria divide again, the four bacteria produced would be almost similar.
Reason (R) : DNA copying involves small inaccuracies in the reproduction process.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the 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
2023 31/2/1 Q18
Generated by claude-sonnet-4-6 · 2026-06-15 06:43 · grounding rag
Model Answer
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
The bacteria are almost similar (not identical) because of small inaccuracies in DNA copying — so R actually does explain A, making (a) the correct choice.
> Answer: (a)
Both A and R are true, and R is the correct explanation of A. DNA copying involves small inaccuracies, so the resulting cells are similar but not identical — hence "almost similar," not exactly identical.
Explanation
- The passage states: "the DNA copies generated will be similar, but may not be identical… the surviving cells are similar to, but subtly different from each other" — this is caused by inaccuracies in DNA copying.
- Since the inaccuracy in DNA copying directly explains why bacteria are only almost similar (not exactly identical), R correctly explains A.
- Examiners expect students to link the cause (inaccurate DNA copying) to the effect (cells being almost similar, not identical). Option (a) is correct.
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