[very_short_answer] In Mendel's monohybrid crosses, one parental trait disappeared in F1 but reappeared in on…

Question

[very_short_answer] In Mendel's monohybrid crosses, one parental trait disappeared in F1 but reappeared in one-fourth of the F2 progeny. How does this observation support the conclusion that organisms carry two copies of a gene for each trait rather than one?

Accepted Answer

## Model Answer The trait reappeared in F2 because F1 plants carried two copies of the gene (one dominant T, one recessive t); only organisms with **two** copies can hide one trait while passing it on, causing its reappearance in tt offspring. Source: Chapter 8, Section 8.2.2 --- ## Explanation The examiner wants you to link the **disappearance in F1** and **reappearance in F2** directly to the idea of **two copies per organism**. Key point: if there were only one copy, a recessive trait could never be "hidden" and then recovered. Mention T and t (or dominant/recessive) to show you understand the mechanism. Keep it to one crisp line for 1 mark.

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