Autosomal Recessive Inheritance Worksheet

Autosomal Recessive Inheritance

Read each question carefully and provide your best answer. Show all your work for Punnett square problems.

1. In autosomal recessive inheritance, an individual must inherit   copies of the recessive allele to express the trait.

2. Parents who are heterozygous for an autosomal recessive trait are often referred to as  .

3. A Punnett square is used to predict the   and   ratios of offspring from a genetic cross.

1. If a child expresses an autosomal recessive trait, at least one of their parents must also express the trait.

2. In autosomal recessive inheritance, males and females are affected with equal frequency.

1. Which of the following genotypes represents a carrier for an autosomal recessive disorder (where 'A' is the dominant allele and 'a' is the recessive allele)?

Cystic Fibrosis (CF) is an autosomal recessive disorder. Let 'F' represent the dominant allele for normal function and 'f' represent the recessive allele for CF.

A man who is a carrier for CF (Ff) marries a woman who is also a carrier for CF (Ff).

1. Draw a Punnett square for this cross.

2. What is the probability that their child will have Cystic Fibrosis?

3. What is the probability that their child will be a carrier for Cystic Fibrosis?

Explain why autosomal recessive traits can sometimes 'skip generations' in a family pedigree.