Question

in a population of squirrels, the allele for bushy tails (b) is dominant over the allele for short tails (b). a bushy tailed squirrel is crossed with a short tailed squirrel and produces a short tailed kits (baby squirrels). what does this tell us about the genotypes of the parents?
a. the bushy - tailed parent must be homozygous dominant (bb) and the short - tailed parent must be homozygous recessive (bb)
b. the bushy - tailed parent must be heterozygous (bb) and the short - tailed parent must be homozygous recessive (bb)
c. the bushy - tailed parent must be homozygous recessive (bb) and the short - tailed parent must be homozygous dominant (bb)
d. both parents must be heterozygous (bb) with bushy tails

Explanation:

Step1: Identify recessive genotype

Short tails are recessive, so short-tailed parent has genotype $bb$, only produces $b$ gametes.

Step2: Analyze offspring genotype

All offspring are short-tailed ($bb$), so they must inherit one $b$ from each parent.

Step3: Deduce bushy parent genotype

The bushy-tailed parent must pass a $b$ allele to all offspring, so its genotype is $Bb$ (heterozygous, bushy phenotype from dominant $B$).

Answer:

B. The bushy-tailed parent must be heterozygous (Bb) and the short-tailed parent must be homozygous recessive (bb)