Autosomal Recessive Inheritance Worksheet

Autosomal Recessive Inheritance

Read each question carefully and answer to the best of your ability. Show all work for Punnett square problems.

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

2. An individual who carries one copy of the recessive allele but does not express the trait is called a  .

3. The observable characteristics of an organism are referred to as its  .

4. Which of the following genotypes represents a homozygous recessive individual?

5. If both parents are carriers (heterozygous) for an autosomal recessive trait, what is the probability that their child will express the trait?

6. In humans, cystic fibrosis is an autosomal recessive disorder. Let 'F' represent the dominant allele for normal function and 'f' represent the recessive allele for cystic fibrosis. A carrier female (Ff) and a carrier male (Ff) plan to have children. Draw a Punnett square to determine the possible genotypes and phenotypes of their offspring. What is the genotypic ratio and phenotypic ratio?

7. If an individual has an autosomal recessive disorder, at least one of their parents must also have the disorder.

8. Autosomal recessive traits are equally likely to affect males and females.

9. Explain why two parents who do not show an autosomal recessive trait can still have a child who expresses the trait. Use terms like 'carrier,' 'heterozygous,' and 'probability' in your explanation.