Question

each of two parents has the genotype brown/blond, which consists of the pair of alleles that determine hair color, and each parent contributes one of these alleles to a child. assume that if the child has at least one brown allele, that color will dominate and the child’s hair color will be brown.
a. list the different possible outcomes. assume that these outcomes are equally likely.
b. what is the probability that a child of these parents will have the blond/blond genotype?
c. what is the probability that the child will have brown hair color?

a. brown/blond and blond/brown
b. brown/brown and blond/blond
c. brown/brown, brown/blond, and blond/blond
d. brown/brown, brown/blond, blond/brown, and blond/blond

b. the probability that a child of these parents will have the blond/blond genotype is \boxed{} (round to two decimal places as needed.)

Explanation:

Part a

Each parent has genotype brown/blond, so each can contribute either brown (B) or blond (b) allele. The possible combinations (outcomes) from the two parents (using a Punnett square - like approach) are: when first parent gives B and second gives B (brown/brown), first B and second b (brown/blond), first b and second B (blond/brown), first b and second b (blond/blond). So the correct option is the one with these four outcomes.

Step1: Identify total outcomes

From part a, we know there are 4 possible equally - likely outcomes: brown/brown, brown/blond, blond/brown, blond/blond.

Step2: Identify favorable outcomes

The favorable outcome for the blond/blond genotype is 1 (only the blond/blond case).

Step3: Calculate probability

Probability is the number of favorable outcomes divided by the number of total outcomes. So probability $P=\frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}}=\frac{1}{4} = 0.25$.

Step1: Identify total outcomes

Again, from part a, total number of outcomes is 4.

Step2: Identify favorable outcomes for brown hair

Brown hair occurs when there is at least one brown allele. The genotypes with brown hair are brown/brown, brown/blond, blond/brown. So there are 3 favorable outcomes.

Step3: Calculate probability

Probability $P=\frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}}=\frac{3}{4}=0.75$.

Answer:

D. brown/brown, brown/blond, blond/brown, and blond/blond

Part b