1. In a B130 class, 20% of the students have dimpled chins (a dominant trait), whereas 80% have non-dimpled chins. (note: the square root of 0.20 = 0.45, the square root of 0.80 = 0.89) What is the frequency of the recessive allele in this population? What is the frequency of the dominant allele in this population? Please show your work. Since we have 80% recessive phenotype (non-dimpled chins), we take the square root of 0.80 to get 0.89. Thus the frequency of non-dimpled chins would be 89% in the population. Allele frequencies will always be: p + q = 1, so since q (recessive) is 0.89, we take 1 - 0.89 which gives 0.11, which is the frequency of dimpled chins. So, 89% is the frequency of non-dimpled chins, and 11% is the frequency of dimpled chins. (The homozygous genotype frequencies (p^2 and q^2) are the squares of the allele frequencies, so that is why we need to take the square root) 2. Genetic drift: A) refers to random changes in gene frequency in a population B) can be brought about by a population bottleneck C) occurs through selective forces in the environment
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