Biology: A Guide to the Natural World

Chapter 12: End of Chapter Quiz

Genetics Problems

1. A man who is a carrier for sickle-cell anemia, a recessive genetic disease, marries a normal, noncarrier woman. What proportion of their children are expected to be afflicted with sickle-cell anemia?  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

2. Hemophilia is an X-linked recessive disease that prevents blood clotting. If a woman who is a carrier for hemophilia marries a normal man, what proportion of their sons are expected to have hemophilia? What is the chance that their first child will have hemophilia? (Remember, the sex of this child is unknown until birth.)  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

3. Neurofibromatosis is a genetic disorder associated with an allele of one autosomal gene. Individuals with neurofibromatosis have uneven skin pigmentation and skin tumors. A man with neurofibromatosis marries a normal woman who does not carry the allele for this disorder. The couple has 5 children, 3 of whom have neurofibromatosis. The most likely explanation for this outcome is that neurofibromatosis is a _____ trait and the man is _____.  

4. Consider the following pedigree for a human autosomal trait. Please refer to the figure in your textbook to help you answer this question.
Is the allele that determines this trait dominant or recessive? Explain your reasoning.  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

5. Using symbols A and a for the dominant and recessive alleles, respectively, what is the genotype of the affected male in the second generation (individual II-3)?  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

6. What is the genotype of this individual’s mate?  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

7. If female III-2 marries a heterozygous man, what proportion of their children are expected to have this trait?  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

8. Consider the following pedigree, which posits a fantasy gene for ear shape, symbolized by P for the regular allele or p for a pointy-shaped allele if this is an autosomal trait; or by for the regular allele or for the pointy allele if this is an X-linked trait. Please refer to the figure in your textbook to help you answer this question.
This pedigree indicates the trait is most likely inherited as an:  

9. What is the genotype of individual I-1?  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

10. If a woman who is a carrier for this trait married individual III-1, what proportion of their children are expected to show this trait? What proportion of their sons are expected to show this trait?  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

11. Construct a pedigree to answer the following question. Red-green color blindness is an X-linked recessive trait. A woman who has a color-blind mother and a father with normal color vision marries a man with normal vision. This couple has a son. What is the chance that the son is color-blind?  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

12. Hyperphosphatemia, a disease that causes a form of rickets (abnormal bone growth and development), is inherited as an X-linked dominant trait. A woman who is heterozygous for the disease allele marries a normal man. What proportion of their sons will have hyperphosphatemia? What proportion of their daughters will have hyperphosphatemia? If hyperphosphatemia were an X-linked recessive trait, how would your answer differ?  

To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

Answer choices in this exercise are randomized and will appear in a different order each time the page is loaded.
 




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