Question

Based on the pedigree, which of the following is an accurate claim about the genotype of Individual 2?


The horse is homozygous dominant because it demonstrates the dwarfism trait.

Option A,The horse is homozygous dominant because it demonstrates the dwarfism trait.

A

The horse is homozygous recessive because it was able to produce an offspring that is also homozygous recessive.

Option B,The horse is homozygous recessive because it was able to produce an offspring that is also homozygous recessive.

B

The horse is heterozygous because it was able to produce a non-dwarf offspring.

Option C,The horse is heterozygous because it was able to produce a non-dwarf offspring.

C

Answer 1

Correct answer: Option C.

Reason: Because the dwarfism trait is dominant in this pedigree, an individual that shows the dominant phenotype but produces a non-dwarf (recessive phenotype) offspring must carry one dominant and one recessive allele (Dd). If Individual 2 were homozygous dominant (DD) all offspring would show dwarfism, so A is wrong. B is also incorrect because producing a homozygous recessive offspring does not prove a parent is homozygous recessive (a heterozygous parent can produce a homozygous recessive child if the other parent contributes the recessive allele).