In a population of cats, the allele for long tails (L) is dominant over the allele for short tails (l). If the frequency of the long tail allele (L) is 0.7 and the population is in Hardy-Weinberg equilibrium, what is the expected frequency of cats with long tails?

• A. 0.21
• B. 0.49
• C. 0.42
• D. 0.91

Answer: (D)

Verified step by step guidance

1. Identify the allele frequencies given: frequency of the dominant allele (L) is \(p = 0.7\), and since there are only two alleles, the frequency of the recessive allele (l) is \(q = 1 - p = 0.3\).
2. Recall that under Hardy-Weinberg equilibrium, the genotype frequencies are given by \(p^2\) for homozygous dominant (LL), \$2pq\( for heterozygous (Ll), and \)q^2$ for homozygous recessive (ll).
3. Calculate the frequency of cats with long tails, which includes both homozygous dominant (LL) and heterozygous (Ll) individuals, because the long tail allele (L) is dominant.
4. Express the total frequency of long-tailed cats as \(p^2 + 2pq\).
5. Substitute the values of \(p\) and \(q\) into the equation and simplify to find the expected frequency of cats with long tails.