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A certain species of rabbit can have either black or grey fur. The allele for black fur is dominant over the allele for grey fur. If a homozygous black rabbit is crossed with a heterozygous black rabbit, what phenotypic ratio will occur in the first generation?

A.
50% black : 50% grey
B.
25% black : 75% grey
C.
100% black : 0% grey
D.
75% black : 25% grey

Respuesta :

sarcasmislife

When completing a Punnett Square, letters are used to designate the alleles involved. The question states that white fur is dominant to black fur. Therefore, "W" will represent the dominant white allele and "w" will represent the black fur. The only genotype that will represent a black furred bunny would be "ww" (homozygous recessive). However, the homozygous dominant (WW) or heterozygous (Ww) genotypes both code for white fur. Yet, since some black bunnies are produced, the white furred bunny must be heterozygous. Thus, the following Punnett Square would be applied:


          w                  w


W       Ww               Ww


w      ww                 ww


Phenotype frequencies:


50% white


50% black


Genotype frequencies:


50% heterozygous


50% homozygous recessive

Oseni

The phenotypic ratio that will occur in the first generation would be 100% black.

Assuming that the black fur allele is represented by B and the grey by b allele, the homzygous black rabbit's genotype will be BB while heterozygous black will be Bb.

Crossing BB with bb:

                     BB     x     Bb

                  BB   Bb   BB   Bb

Since B and dominant over b:

First generation:

1/2 BB - Black

1/2 Bb - Black

Thus, the phenotypic ratio in the first generation would be 100% black.

More on phenotypic ratios can be found here: https://brainly.com/question/3840678?referrer=searchResults

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