Variation in a phenotypic feature such as milk yield results from both genetic and environmental influences. Goats also show differences in milk yield between the first lactation and the second lactation. Suggest, with reasons, whether the variation in milk yield between the first lactation and the second lactation, as shown in Table 2.1, is genetic or environmental.
The variation at position 5752 of the gene coding for a growth factor is caused by a substitution mutation from G to C. Using Table 2.1, describe the significance of the substitution from G to C.
For a population of 268 Xinong Saanen goats: • the frequency of the C allele ($q$) is $0.30$ • the frequency of the G allele ($p$) is $0.70$ The Hardy-Weinberg principle can be used to predict how many goats have CC, CG and GG genotypes in the population, using the equation: $p^2 + 2pq + q^2 = 1$ For instance, the expected number of goats with genotype GG can be predicted to be 131. Use the Hardy-Weinberg principle to predict the numbers of goats with genotypes CC and CG in this population of Xinong Saanen goats. number of goats with genotype CC ................. number of goats with genotype CG .................
If your predicted figures in (b)(i) are close to the actual numbers in Table 2.2, that would show that the Xinong Saanen population is in Hardy-Weinberg equilibrium. State the name of a statistical test that could be used to determine whether the Xinong Saanen population is in Hardy-Weinberg equilibrium or not.
According to the Hardy-Weinberg principle, the predicted numbers of goats with each genotype in the Guanzhong population are CC $= 16$, CG $= 135$, GG $= 289$. These values are very different from the actual values in Table 2.2. With reference to Table 2.2, describe the evidence showing that the Guanzhong population is not in Hardy-Weinberg equilibrium and suggest reasons for this.
Goats can be genetically modified so that human proteins are produced in their milk. In 2009, an anti-clotting protein made in this way was approved for use as a drug in people who lack the protein. State one ethical benefit and one ethical problem of producing medicinal drugs from the milk of genetically modified goats.