Question

Fur color is an inherited trait controlled by one pair of alleles where one form is dominant over the other. The fur color is either brown or gray. Two brown animals mate and produce 12 offspring. Three (25 percent) of the offspring produced are gray and nine (75 percent) are brown.
Based on the above data answer the follow questions

Determine which fur color is dominant and which is recessive.

Assign letter symbols for the alleles in your answer.

Answer the questions using at least two or three complete sentences.

Answer 1

1) Brown fur colour is dominant, gray colour is recessive.

2) Alleles for brown colour is Bb and alleles for gray colour is bb.

3) The parents are heterozygous dominant that is each one of them has one allele for recessive trait gray colour.

Explanation:

Alleles for fur colour brown is dominant

Alleles for fur colour gray is recessive.

Genotype for brown is BB, Bb

genotype for gray colour is bb

Two brown mated producing gray offspring must be heterozygous. the punnet square shows:

    B  b

B BB Bb

b Bb  bb

75% of offspring are brown

25% of offspring are gray      3:1 phenotypic ratio, genotypic ratio 1:2:1

From the punnet square

The brown colour is dominant.

The gray colour is recessive.

Alleles gray colour is bb

alleles for brown is BB, Bb

The parents are heterozygous that is why when two recessive alleles combine of either parents in a progeny gray colour is expressed.