In Mendel's dihybrid cross, two traits — seed shape and seed colour — are inherited independently. Explain why this independent inheritance would be impossible if each parent contributed a single, unbroken set of all genes to their offspring.
Generated by claude-sonnet-4-6 · 2026-06-26 01:04 · grounding rag
Model Answer
In Mendel's dihybrid cross, factors (genes) controlling seed shape and seed colour recombine independently when forming a zygote, producing new combinations like tall with wrinkled seeds or short with round seeds in F2 offspring.
If each parent contributed a single, unbroken set of all genes, the traits would always stay linked together and pass as one unit. Independent recombination of individual factors would be impossible — new combinations of traits could never arise in offspring. Mendel's results are only explained by each trait being inherited separately, not as part of an intact, inseparable package.
Source: Chapter 8, Section 8.2.2
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Explanation
- The examiner wants you to connect the dihybrid cross outcome (new trait combinations in F2) to the mechanism — independent inheritance of separate gene pairs.
- Key idea: if genes were inherited as a single unbroken set, all traits from one parent would always travel together; reshuffling would be impossible.
- Use the textbook phrase: "factors controlling for seed shape and seed colour recombine to form zygote."
- Avoid over-explaining Mendel's ratios — that is not asked. Focus on why independent inheritance requires genes to be separable units.