Inheritance Structured Questions | Cambridge O Level Biology

Biology 5090 · Question 1[7 marks]

In guinea pigs, black coat colour is determined by a dominant allele (B) and brown coat colour is determined by a recessive allele (b).

(a)

Distinguish clearly between the terms genotype and phenotype.

[2]

(b)

A male black guinea pig of unknown genotype is mated with a female brown guinea pig. Over several litters, they produce 14 black offspring and 15 brown offspring.

[3]

(i)

State the genotype of the female brown parent.

[1]

(ii)

Deduce the genotype of the male black parent, giving a scientific reason based on the offspring produced.

[2]

(c)

In human ABO blood groups, alleles $I^A$ and $I^B$ are codominant, while allele $I^O$ is recessive. A man with Blood Group A and a woman with Blood Group B have a child with Blood Group O. State the genotypes of both parents and deduce the probability of their next child having Blood Group AB.

[2]