Question 48

A breeder wants to find out whether a rabbit showing the dominant form also carries a recessive allele. Which cross answers the question?

Cross it with a rabbit that has two dominant alleles
Cross it with one of its own offspring, chosen at random
Do not cross it at all, and examine its fur closely instead
Cross it with a rabbit that has two recessive allelesCorrect answer

Explanation

A partner that can only supply recessive alleles lets every offspring display the tested rabbit's contribution directly, so a single offspring with the recessive form proves the hidden allele is there. A partner with two dominant alleles would mask that contribution in every offspring, leaving the question open.

Explanation

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