Question

this passage describes the coat graying trait in horses:
your hair may turn gray or white as you grow older. some horses go through a similar process called coat graying as they age. these horses are usually a darker color, such as brown or black, when they are born. over time, the hairs of their coats lose their original color and become gray or white.
in a group of horses, some individuals have coat graying and others do not. in this group, the gene for the coat graying trait has two alleles. the allele for having a graying coat (g) is dominant over the allele for not having a graying coat (g).
this punnett square shows a cross between two horses.
punnett square with top row g, g and left column g, g; cells: gg, gg, gg, gg
what is the probability that a horse produced by this cross will be homozygous recessive for the coat graying gene?
0%
25%
50%
75%
100%

Explanation:

Step1: Identify target genotype

We need the homozygous recessive genotype, which is $gg$.

Step2: Count total and target outcomes

Total Punnett square outcomes: $4$. Number of $gg$ outcomes: $2$.

Step3: Calculate probability

Probability = $\frac{\text{Number of } gg \text{ outcomes}}{\text{Total outcomes}} = \frac{2}{4} = 0.5 = 50\%$

Answer:

50%