Assuming basic Mendelian inheritance, which of the following are the expected wi

Question

Assuming basic Mendelian inheritance, which of the following are the expected wing phenotype ratios for the F2?

You are a scientist trying to understand how wing shape is inherited in fruit flies. You have flies that are pure-breeding for the wild-type wing shape & flies pure-breeding for a mutant wing shape (zigzag wings). You breed these flies and notice that the F1 are 100% wing mutants. Using your F1 data you've constructed a null & alternative hypothesis. Now you want to attempt to falsify the null hypothesis so you cross a male & female from your F1 generation flies. Assuming basic Mendelian inheritance, which of the following are the expected wing phenotype ratios for the F2? 50% wild-type, 50% wing mutant O 25% wild-type, 75% wing mutant O 100% wing mutant 75% wild-type, 25% wing mutant 100% wild-type

Explanation / Answer

This case represents to be a general case when the Mendelian pattern of inheritance is being followed and a monohybrid cross is performed in the F1 generation. Thus, the information suggests that the flies in the F1 generation all bear a common genotype i.e. mutant, say Aa in nature. These flies are selfed and the F2 is obtained. Thus, this selfing would obtain following cross:

Genotype: AA: Aa: aa : 1:2:1

Phenotpye: Parental (AA and aa): mutant (Aa):: 1:1

This suggests that choice 1 is the correct answer.

A a A AA Aa a Aa aa

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