BMS100 Past Test Questions
Chapter 20, Fall 2009
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  1. In the disease called cystic fibrosis (CF), mucus is too "thick," causing breathing difficulties and respiratory infections. What is the genetic basis of CF?
    1. The affected individual has a dominant gene that codes for production of thick mucus.
    2. The affected individual is lacking the dominant gene that codes for production of normal mucus.
    3. The affected individual is heterozygous with respect to the mucus production gene.
    4. An unusual mutation caused a recessive gene to become dominant.

  2. If a gene exists in two alleles (forms), how many different genotypes can occur?
    1. two
    2. three
    3. four
    4. six

  3. If a gene exists in two alleles (forms), one dominant and one recessive, how many different phenotypes can occur?
    1. two
    2. three
    3. four
    4. six

  4. A carrier of a recessive gene is
    1. heterozygous
    2. homozygous recessive
    3. likely to experience direct, personal health consequences caused by the gene
    4. A. and B.
    5. B. and C.

  5. If two carriers of CF produce children, what is the probability that a child of theirs will be completely free of the CF gene (unable to pass the gene to subsequent generations)?
    1. 0%
    2. 25%
    3. 50%
    4. 75%
    5. 100%

  6. True or false? A person with blood type A cannot have a type O child,
    1. True.
    2. False.

  7. Given the following key: A = autosomes, X = X chromosome, Y = Y chromosome; what is the correct ranking according to number of genes contained, from greatest to least?
    1. X > A > Y
    2. X > Y > A
    3. A > X > Y
    4. A and then X and Y in a tie

  8. The male karyotype does not include
    1. an X chromosome inherited from the mother
    2. an X chromosome inherited from the father
    3. a Y chromosome inherited from the father
    4. 22 autosomes inherited from the mother
    5. 22 autosomes inherited from the father

  9. What chromosomes are present in a normal ovum ("egg")?
    1. 22 pairs of autosomes
    2. one X chromosome
    3. one pair of X chromosomes
    4. both A. and B.
    5. both A. and C.

  10. If a woman is a carrier of the gene for X-linked color blindness, what percentage of her ova ("eggs") will contain the "defective" gene that causes color blindness?
    1. 0%
    2. 50%
    3. 100%
    4. a variable number between 1 and 22

  11. Huntington's disease is caused by a dominant gene located on an autosome. If a woman who does not have the HD gene has children with a man who has HD, what is the probability that a child of theirs will eventually have HD?
    1. 0%
    2. 25%
    3. at least 50% (possibly more depending on the genotype of the man)
    4. at least 75% (possibly more depending on the genotype of the man)
    5. 100%

  12. In which case are females more likely to be directly affected by an X-linked gene?
    1. when the gene is dominant
    2. when the gene is recessive
    3. both A. and B.
    4. none of the above (females are not affected by X-linked genes)

  13. Hemophilia is caused by an X-linked recessive gene that does not code for functional blood clotting factors. Hemophiliac men are more likely to have hemophiliac _?_ than are non-hemophiliac men.
    1. sons
    2. daughters
    3. both of the above
    4. none of the above

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