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BIO 140 Human Biology I - Questions and Solutions

Patterns of Inheritance -Solutions

Review Questions

1. Marfan syndrome is inherited in an autosomal dominant pattern. Which of the following is true?

  1. Female offspring are more likely to be carriers of the disease.
  2. Male offspring are more likely to inherit the disease.
  3. Male and female offspring have the same likelihood of inheriting the disease.
  4. Female offspring are more likely to inherit the disease.

2. In addition to codominance, the ABO blood group antigens are also an example of ________.

  1. incomplete dominance
  2. X-linked recessive inheritance
  3. multiple alleles
  4. recessive lethal inheritance

3. Zoe has cystic fibrosis. Which of the following is the most likely explanation?

  1. Zoe probably inherited one faulty allele from her father, who is a carrier, and one normal allele from her mother.
  2. Zoe probably inherited one faulty allele from her mother, who must also have cystic fibrosis, and one normal allele from her father.
  3. Zoe must have inherited faulty alleles from both parents, both of whom must also have cystic fibrosis.
  4. Zoe must have inherited faulty alleles from both parents, both of whom are carriers.

 

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Critical Thinking Questions

1. Explain why it was essential that Mendel perform his crosses using a large sample size?

Solution: By using large sample sizes, Mendel minimized the effect of random variability resulting from chance. This allowed him to identify true ratios corresponding to dominant–recessive inheritance.

2. How can a female carrier of an X-linked recessive disorder have a daughter who is affected?

Solution: The only way an affected daughter could be born is if the female carrier mated with a male who was affected. In this case, 50 percent of the daughters would be affected. Alternatively, but exceedingly unlikely, the daughter could become affected by a spontaneous mutation.

 

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OpenStax, Patterns of Inheritance. OpenStax CNX. Jun 4, 2013 http://cnx.org/contents/ee2dfa4c-b9c6-41ea-8be5-8d8117f4e9d3@3. © Jun 4, 2013 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License 3.0 license.