Question

For hair color, having dark/brunette hair is dominant to having light or blond hair. Olivia Keller is blond but her mother, Mrs. Keller is brunette. Mr. Keller is also brunette. Use a Punnett Square to show whether Olivia could be the Kellers’ daughter.

Answer 1

By using a Punnett square, we can deduce that Olivia can be the biological daughter of Mrs. and Mr. Keller if both parents are carriers of the recessive allele for blonde hair (Bb).

Step-by-step explanation:

Understanding Inheritance with a Punnett Square

To answer whether Olivia could be the biological daughter of the Kellers, we can create a Punnett square. This genetic tool combines alleles from both parents to predict the possible hair colors of their offspring. Given that having dark or brunette hair is a dominant trait over having light or blonde hair, we can use 'B' to represent the dominant allele for brunette hair and 'b' for the recessive allele for blonde hair.

Since Olivia is blonde (bb), we know she has two recessive alleles. For her to be blonde, both her parents must carry at least one recessive 'b' allele. Let's assume Mrs. Keller is heterozygous (Bb), as she has brunette hair, and Mr. Keller could be either homozygous dominant (BB) or heterozygous (Bb).

• If Mrs. Keller is Bb and Mr. Keller is BB, all their children are predicted to be brunette.
• If Mrs. Keller is Bb and Mr. Keller is also Bb, there is a 25% chance for each child to be blond (bb).

Therefore, Olivia could indeed be their daughter if both parents are carriers of the recessive blonde allele (Bb).

Answer 2

Olivia could be the Keller's daughter if both parents are heterozygous for their brunette hair coloration. Please find the punnet square in the attachment section.

Step-by-step explanation:

According to this question that involves a gene coding for hair color in humans, the allele for dark/brunette hair (B) is dominant to the allele for light/blond hair (b). This means that a heterozygous individual (Bb) will have a brunette hair coloration.

Olivia Keller is said to have blond hair but her mother, Mrs. Keller and father, Mr. Keller both have brunette hair coloration. Since Olivia is blond (recessive), she must have a genotype "bb". However, this is possible if both of her parents i.e. Mr and Mrs. Keller have a heterozygous genotype (Bb).

From the punnet square of the cross, Bb × Bb, in the attachment section, it can be observed that brunette color (BB, Bb, Bb) and blond color (bb) were produced in the offsprings in the ratio 3:1. This means that it is very likely that Olivia could be the Keller's daughter.