Q1. [2] § Introduction § 8.1 ACCUMULATION OF VARIATION DURING REPRODUCTION
What is variation ? List two main reasons that may lead to variation in a population.
Previously asked in CBSE board exam
2022 31/1/1 Q5 (a)
Generated by claude-sonnet-4-6 · 2026-06-15 06:53 · grounding rag
Model Answer
Variation is the difference in characteristics among individuals of the same species arising during reproduction.
Two main reasons for variation:
- Inaccurate DNA copying — Small errors occur during DNA replication, producing subtle differences in the new individual.
- Sexual reproduction — Combining DNA from two different individuals creates new combinations of variations in the offspring.
Source: Chapter 7, Section 7.1.1 & 7.3.1; Chapter 8, Section 8.1
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Explanation
- The definition should mention "differences among individuals of the same species" linked to reproduction — examiners expect this context.
- For the two reasons, the textbook specifically highlights DNA copying errors and sexual reproduction (combining DNA from two parents). Naming both scores full marks.
- Do not confuse "variation" with "mutation" — use the textbook terminology.
- At 2 marks, one line for the definition and two labelled points is the ideal format.
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