Question

A middle school student is studying genetics in their science class. They are using punnett squares to determine the probability that a trait will be passed on from one generation to the next. The student creates a punnett square for eye color using the genotypes of their parents. A big B represents the gene for brown eyes, and a little b represents the gene for blue eyes.
Select the statement(s) that accurately describe the outcomes of the punnett square.

The student had a 50 percent chance of inheriting brown or blue eyes.

In order to have blue eyes, the student would have to inherit the alleles for blue eyes from both parents.

In order to have brown eyes, the student would need to inherit the alleles for brown eyes from both parents.

The allele for brown eyes is dominant to the allele for blue eyes.

The student had a 75 percent chance of inheriting blue eyes

Answer 1

Assuming both parents are heterozygous (Bb × Bb), the Punnett square outcomes are: BB, Bb, Bb, bb (25% BB, 50% Bb, 25% bb). From that:

- True: "In order to have blue eyes, the student would have to inherit the alleles for blue eyes from both parents." (blue is recessive, so bb)
- True: "The allele for brown eyes is dominant to the allele for blue eyes." (B is dominant over b)

- False: "The student had a 50 percent chance of inheriting brown or blue eyes." (actual chances are 75% brown, 25% blue)
- False: "In order to have brown eyes, the student would need to inherit the alleles for brown eyes from both parents." (one B is enough: BB or Bb gives brown)
- False: "The student had a 75 percent chance of inheriting blue eyes." (it's 75% chance of brown, not blue)