Any help and explanation will be greatly appreciated Q46 Ima

Q4.6. Imagine a species whose eye color is determined by a receptor molecule called EyeC. When EyeC is not activated, CAMP levels in the cell are low and yellow pigment is produced. When EyeC is activated by the binding of a signal molecule, CAMP levels rise and blue pigment is produced. The P allele codes for a version of EyeC that responds to signal molecules and therefore turns on and off, resulting in green eye color (from both blue and yellow pigment). The Q allele codes for a version of EyeC that is always activated, even when signal molecules are not present. Assuming EyeC functions similarly to MC1R, which of the following statements is the best prediction of the dominance relationship between alleles P and Q as well as the phenotype for PQ individuals? Q is dominant over P, and the eye color of PQ individuals is blue. Q is dominant over P, and the eye color of PQ individuals is yellow. P is dominant over Q, and the eye color of PQ individuals is blue. Pand Q are codominant, and the eye color of PQ individuals is green.

Solution

4.6 (D). P and Q are codominant, and the eye color of PQ individuals is green.

As provided in the question, the eyeC version of Q is always activated and P switches on and off but gives green eye color with both yellow and blue pigments. So, eye color of PQ individuals will be green due to P.

4.7 (C). The allele frequencies will be 60% dominant and 40% recessive.

As provided in the question, current allele frequency distribution is 60% dominant and 40% recessive. So, after many generations the same frequency level is most likely to be inherited in progenies as a result of random mating. Unless some mutation occurs.

4.8 (D). It is impossible to say, because dominance cannot be inferred from fitness.

Though, homozygotes with allele 1 give long horns and that is an advantage for protection to the lizards. But, we dont know that having horns is a positive change in lizards population, or it is just a mutational change inherited by accident and passing on through allele 2. So, just because they are giving an advantage, does not tell us whether allele 1 ia dominant or allele 2 is dominant. Because in general ecosystem, the lizards have no horns.