Genetics II – Post Test
Name ________________________________________
•
February 23, 2013
SC.912.L.16.2* Discuss observed inheritance patterns caused by various modes of
inheritance, including dominant & recessive ( simple inheritance) & co-dominant, sexlinked, polygenic, and multiple alleles (complex inheritance).
1. A person who has a disorder caused by a recessive allele is
a. considered a carrier of the disorder.
b. homozygous for the recessive allele.
c. unable to pass the allele to offspring
d. certain to have offspring with the disorder.
2. Suppose a person is a carrier for a genetic disorder. Which of the following phrases about
this person is true?
a. does not have the disorder but can pass it on.
b. will develop the disorder only late in life
c. cannot pass the disorder to sons, just daughters
d. the allele is not passed on due to Y chromosome inactivation.
3. One of the parents of a child has phenylketonuria (PKU), which is caused by recessive
alleles. The other parent does not have the PKU alleles. What is the chance that the
couple will have a child with PKU?
a. 0%
b. 50%
c. 75%
d. 100%
4. A plant that is homozygous for red flowers is crossed with a plant that is homozygous for
white flowers. In the case of incomplete dominance, the flowers of the offspring will be
a. red and white.
b. white only.
c. pink only.
d. red only.
5. In the case of codominant alleles, a plant that is homozygous for red flowers that is
crossed with a plant that is homozygous for white flowers will produce flowers that are
a. red and white spotted.
b. completely white.
c. dark pink all over.
d. pink and red.
6. The table lists the trials for fruit color where allele R exhibits incomplete dominance over
the R’ allele.
Heterozygous fruit have orange phenotypes. What percentage of offspring are expected
to have an orange phenotype if the parent plants are orange (RR’) and yellow(R’R’)?
a. 25%
b. 50%
c. 75%
d. 100%
7. Alleles for the A and B blood cell antigens are codominant. The condition where no
antigens are present on the blood cells (type O blood) is a recessive trait. Which set of
parents can most likely produce a child with type O blood?
a. One parent with type AP blood, and the other parent with type A blood.
b. One parent with type AB blood, and the other parent with type O blood.
c. One parent with heterozygous type A blood, and the other parent with type O
blood
d. One parent with homozygous type A blood, and the other parent with
homozygous type B blood
8. Unlike the traits studied by Mendel, most traits are produced by genes with
a.
b.
c.
d.
sex linkage.
only one allele.
dominance and recessiveness.
multiple alleles.
9. Human height occurs in a continuous range because it is affected by the interaction of
several genes, making it a
a. autosomal trait.
b. sex-linked trait.
c. polygenic trait.
d. codominant trait.
10. Eye color, hair color, and skin color are polygenic traits. Polygenic traits result from
a. recessive genes.
b. many genes.
c. codominant genes.
d. epistatic genes.
11. A human baby boy inherits a recessive allele from his mother. In which circumstance
would he most likely show the trait coded for by the recessive allele?
a. The baby inherits the dominant allele from his father.
b. The allele is on an autosomal chromosome and the baby is a twin
c. The allele is on the X chromosome.
d. The allele is for a lethal disease
12. Hemophilia is a sex linked, recessive trait. Which of the following describes the
probability of hemophilia in the offspring of a man who does not have hemophilia and a
woman whose father is hemophiliac?
a. Each of their sons will have hemophilia
b. None of their daughters will have hemophilia
c. Their sons have a 25% chance of having hemophilia
d. There is a 50% chance that their daughters will have hemophilia
13. A chart that traces the phenotypes and genotypes within a family is called a
a.
b.
c.
d.
pedigree.
karyotype.
Punnett square.
chromosome map.
14. Identical twins who are raised apart can have differences that last a lifetime. This is
evidence that
a. phenotype differences happen through epistatic genes.
b. genotype can change over time.
c. environment and genotype interact to affect phenotype.
d. codominance affects genotype.