In a cross between a strain of large guinea pigs and a strain of small guinea pigs, the F₁ are phenotypically uniform, with an average size about intermediate between that of the two parental strains. Among 1014 F₂ individuals, 3 are about the same size as the small parental strain and 5 are about the same size as the large parental strain. How many gene pairs are involved in the inheritance of size in these strains of guinea pigs?

In studies of human MZ and DZ twin pairs of the same sex who are reared together, the following concordance values are identified for various traits. Based on the values shown, describe the relative importance of genes versus the influence of environmental factors for each trait.Trait ConcordanceMZ DZ _Blood type 100 65Chicken pox 89 87Bipolar disorder 67 13Schizophrenia 72 12Diabetes 62 15Cleft lip 51 6Club foot 40 4

During a visit, your grandparents comment on how tall you are compared with them. You tell them that in your genetics class, you learned that height in humans has high heritability, although environmental factors also influence adult height. You correctly explain the meaning of heritability, and your grandfather asks, 'How can height be highly heritable and still be influenced by the environment?' What explanation do you give your grandfather?

New Zealand lamb breeders measure the following variance values for their herd.Trait VP VG VABody mass (kg) 42.4 20.5 7.4Body fat (%) 38.9 16.2 5.7Body length (cm) 51.6 26.4 8.1Calculate the broad sense heritability (H²) and the narrow sense heritability (h²) for each trait in this lamb herd.

New Zealand lamb breeders measure the following variance values for their herd.Trait VP VG VABody mass (kg) 42.4 20.5 7.4Body fat (%) 38.9 16.2 5.7Body length (cm) 51.6 26.4 8.1How would you characterize the potential response to selection (R) for each trait?

Cattle breeders would like to improve the protein content and butterfat content of milk produced by a herd of cows. Narrow sense heritability values are 0.60 for protein content and 0.80 for butterfat content. The average percentages of these traits in the herd and the percentages of the traits in cows selected for breeding are as follows.Trait Herd Average Selected CowsProtein content 20.2% 22.7%Butterfat content 6.5% 7.4%Which trait is likely to be the most responsive to artificial selection applied by the cattle breeders through selection of cows for mating?

Cattle breeders would like to improve the protein content and butterfat content of milk produced by a herd of cows. Narrow sense heritability values are 0.60 for protein content and 0.80 for butterfat content. The average percentages of these traits in the herd and the percentages of the traits in cows selected for breeding are as follows.Trait Herd Average Selected CowsProtein content 20.2% 22.7%Butterfat content 6.5% 7.4%Determine the selection differential (S) for each trait in this herd.