Practice Punnett Square Problems

 

1. A heterozygous yellow, round pea is crossed to a homozygous green homozygous wrinkled pea.  What are the possible phenotypes and genotypes of the offspring?  What is the likelihood of having a fully homozygous offspring?

Solution

 

2. This disease is inherited as a autosomal dominant disease.  A heterozygous male marries a homozygous recessive female.  Draw a Punnett square of the possible offspring.  What is the chance they will have an unaffected child?

Solution

 

3. Colorblindness is inherited as a sex-linked recessive disease.  An affected male marries a heterozygous female.  Draw a Punnett square of the possible offspring.  What is the chance that they will have an affected child?  Could any of their daughters be affected?

Solution

 

4. Hairy ears is inherited as a Y-linked trait.  A man with hairy ears marries a woman with normal ears.  Draw a Punnett square of the possible offspring.  Could any of their children have hairy ears? 

Solution

 

5. This disease is inherited as sex-linked dominant disease.  An affected male marries a homozygous recessive female.  Draw a Punnett square of the possible offspring.  What is the likelihood that any child they have will be affected.  Would the parents of the father (grandparents of these offspring) have been affected?

Solution