Fig. 9.1 illustrates a cross involving two guinea pigs. The male guinea pig is pure-breeding for black fur colour, while the female guinea pig is pure-breeding for white fur colour. The allele for black fur colour is represented by B and the allele for white fur colour is represented by b. All four offspring had black fur.
(a(i))[1]
State the phenotypes shown by each parent guinea pig in Fig. 9.1. phenotype of the male; phenotype of the female.
(a(ii))[1]
State the genotype belonging to the female parent guinea pig.
(a(iii))[1]
All the offspring are heterozygous. State the genotype of one heterozygous offspring.
(b(i))[1]
State every possible genotype for the three offspring labelled A, B and C.
(b(ii))[1]
State the phenotypic ratio in the second generation of guinea pigs.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “male with black fur; female with white fur” …