Question

The American Curl cat breed has a dominant mutation causing an unusual ear shape that gives the cat a "teddybear" look. If the frequency of the mutant allele is 1% in a population of cats at Hardy-Weinberg equilibrium, what proportion of the cats have American Curl ears, to 1 significant figure?

	a.	0.1 (10%)
	b.	0.01 (1%)
	c.	You can't tell from this information
	d.	0.0001 (0.01%)
	e.	0.02 (2%)

Answer 1

Let the gene for dominant mutation be A and the normal gene be a. Therefore the American curl cat breed will express the dominant mutation if the genotype is AA whereas Aa will be carrier and aa will be normal. Let the frequency of mutant allele be p and normal allele is q. According to Hardy Weinberg equilibrium, p+q=1.

therefore, frequency of the mutant allele,

proportions of the cats having American curl ears, (0.01%)

So option (d) is the correct answer.