3.2 Exercise: The Punnett Square

Most plants and animals are considered diploid organisms – that is, it takes a combination of male and female gametes to create a zygote. The resulting offspring receive at least one allele (variant of a gene) from each parent. Depending upon whether they receive the same (homozygous) or different (heterozygous) alleles can influence whether the dominant or recessive trait emerges.

To understand Mendel’s work in action, watch the video below. Then practice reading the Punnett Square below.

Let’s say you are trying to determine the likelihood a child will be born with blue eyes. Both of their parents have brown eyes (capital B), but they also both carry a recessive gene for blue eyes (lower case b). First, determine what the resulting genotype is for each quadrant of the Punnett Square.

Based upon the Punnett square, what are the chances the child will be born with blue eyes? Click here for the answer.