Question

Imagine that we mate two black Labrador dogs with normal vision and find that three of the puppies are like the parents, but one puppy is chocolate with normal vision and another is black with PRA (progressive retinal atrophy, a serious disease of vision). We can conclude that _________.A) both of the parents are homozygous for both traits. B) the same alleles that control coat color can also cause PRA. C) the alleles for color and vision segregate independently during gamete formation. D) the alleles for color and vision segregate dependently during gamete formation.

Answer 1

C. the alleles for color and vision segregate independently during gamete formation.

Step-by-step explanation:

According to Mendel's law of independent assortment that during gamete formation, each pair of alleles segregates independently of the other pairs of alleles. The allele composition of one gene does not have effect on the allele of the other gene

From the question, mating two black Labrador dogs with normal vision giving birth to three puppies which looks like the parents, one chocolate puppy with normal vision and another black puppy with a serious disease of vision reveals that each of the puppy (especially the chocolate and diseased puppy) might have inherited random homologous chromosomes independently for either of the parents

Answer 2

Step-by-step explanation:

Both parents have black color and normal vision but some of their progenies show brown color and some shows PRA, this reveals the brown coat color and PRA are recessive traits and both parents are heterozygous. The progenies include black normal vision, brown normal vision and black, PRA, that is the alleles for these genes separate independently of each other.

Let us denote the alleles as B-black, b-brown and P-normal vision, p-PRA, then the genotype of the heterozygous parent is BbPp, alleles separate independently of each other so the possible gametes are alleles for the color and vision segregate independently during gamete formation.

Thus, option C is correct.