In Martians, black eyes (B) are dominant over yellow eyes (b). A black-eyed Martian marries a yellow-eyed Martian and they have three children, two of the Martian kids have black eyes and one has yellow eyes. Draw a Punnett square that illustrates this

1. Since the male will either be (BB) or (Bb) and the female is recessive, then is the male (BB) or (Bb)? Explain your answer.

2. What are the genotypes of the children?

3. Display your Punnett square.

How do i do this?

Answer and Explanation:

Available data:

Cross: black-eyed Martian with a yellow-eyed Martian

Since the male will either be (BB) or (Bb) and the female is recessive, then is the male (BB) or (Bb)? Explain your answer.

Black, B, is dominant over yellow, b, so the black-eyed male must have the phenotype B-. We do not know yet if the individual´s genotype is Bb or BB.

The genotype of the yellow-eyed female is bb.

So the cross is: B-  x  bb

This couple had 3 children: 2 of them are black-eyed (B-) and 1 of them is yellow-eyed (bb). To be yellow-eyed, an individual needs to receive a recessive allele from each of the parents. So this means that the black-eyed male is heterozygous for the trait because he must have given one recessive allele to his/her yellow-eyed child.

Cross:

Parental) Bb   x   bb

Gametes) B   b    b   b

Punnet square)   B        b

                      b     Bb       bb

                      b     Bb       bb

F1) Progeny genotype: 1/2 Bb, black-eyed

                                      1/2 bb, yellow-eyed

What are the genotypes of the children?

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).