Each of two parents has the genotype red divided by brown, which consists of the pair of alleles that determine hair color, and each parent contributes one of those alleles to a child. assume that if the child has at least one red allele, that color will dominate and the child's hair color will be red.

Q1) List the different possible outcomes. Assume that these outcomes are equally likely.

the dominant allele - red (R)

recessive allele - brown (r)

both parents are heterozygous, meaning each of them have both alleles. one allele from each parent will be passed on to the child. therefore the child will have total of 2 alleles, one allele from each parent.

Parents              R/r     x    R/r

possible outcomes - R/R    R/r     r/R    r/r

dominant allele is when at least one allele being there in the genotype will express the corresponding phenotype. Recessive allele is when both alleles need to be recessive for it to be expressed.

outcomes:

 red - R/R , R/r, r/R and brown - r/r 

Q2) What is the probability that a child of these parents will have the brown divided by brown genotype?

There are 4 outcomes possible as stated in the previous question. From these 4 outcomes, we are being asked to calculate the probability of child having the genotype r/r. both alleles should be brown colour.

the 4 outcomes - R/R , R/r, r/R, r/r 

as brown is the recessive allele, both alleles need to be brown for it to be expressed. only one of these 4 outcomes have r/r

Probability of r/r - 1/4 = 0.25

Q3) What is the probability that the child will have red hair color?

as red is the dominant allele, at least one of the alleles being present would express the red phenotype. from the 4 outcomes ;

R/R , R/r, r/R, r/r - three of these have at least one R allele -R/R, R/r, r/R

therefore in three of these outcomes, red will be expressed.

Probability of red being expressed - 3/4 = 0.75