Questions
1. The greatest distance among the three genes is between a and c. What
does this mean?
a. Gene
a is closest to b.
b. Genes
are in the order: a–b–c.
c. Gene
a is not recombining with c.
d. Gene
a is between b and c.
2. Which of the following mutations is most likely to cause a phenotypic
change?
a. a
duplication of all or most introns
b. a
large inversion whose ends are each in intergenic regions
c. a
nucleotide substitution in an exon coding for a transmembrane domain
d. a
single nucleotide deletion in an exon coding for an active site
3. Genes a and b are 20 cM apart. An a+ b+/a+ b+ individual was mated
with an a b/a b individual. If the F1 was crossed to a b/a b individuals, what
offspring would be expected, and in what proportions?
a. 40%
a+ b+/a b, 40% a b/a b, 10% a+ b/a b, 10% a b+/a b
b. 50%
a+ b+/a b, 50% a b/a b
c. 40%
a+ b+/a b, 10% a b/a b, 40% a+ b/a b, 10% a b+/a b
d. 40%
a+ b+/a b, 10% a b/a b, 10% a+ b/a b, 40% a b+/a b
4. 5-Bromuracil in keto form induces mutations because it
a.
replaces a T and binds to G rather than A
b.
replaces a G and binds to A rather than C
c.
changes the binding affinity of G
d. changes the
binding affinity of
5. A certain kind of snail can have a right-handed direction of shell coiling
(D) or left-handed coiling (d). If direction of coiling is due to a protein
deposited by the mother in the egg cytoplasm, then a Dd egg-producing snail and
a dd sperm-producing snail will have offspring of which genotype(s) and phenotype(s)?
a. 1/2
Dd:1/2 dd; all right coiling
b. all
Dd; all right coiling
c. 1/2
Dd:1/2 dd; half right and half left coiling
d. all Dd; all left
coiling
6. A couple has a child with Down syndrome. The mother is 39 years old
at the time of delivery. Which of the following is the most probable cause of
the child's condition?
a. The
woman inherited this tendency from her parents.
b. One
member of the couple carried a translocation.
c. One
member of the couple underwent nondisjunction in somatic cell production.
d. One member of the
couple underwent nondisjunction in gamete production.
7. Suppose that a gene on human chromosome 18 can be imprinted in a given
pattern in a female parent but not in a male parent. A couple in whom each
maternal meiosis is followed by imprinting of this gene have children. What can
we expect as a likely outcome?
a. All
sons but no daughters will bear their mother's imprinting pattern.
b. All
daughters but no sons will bear their mother's imprinting pattern.
c. All
sons and daughters will have a 50% chance of receiving the mother's imprinting
pattern.
d. All
the children will bear their mother's imprinting pattern but only daughters
will then pass it dow
8. A phenotypically normal prospective couple seeks genetic counseling
because the man knows that he has a translocation of a portion of his
chromosome 4 that has been exchanged with a portion of his chromosome 12.Although
he is normal because his translocation is balanced, he and his wife want to
know the probability that his sperm will be abnormal. What is your prognosis
regarding his sperm?
a. 1/4
will be normal, 1/4 will have the translocation, and 1/2 will have duplications
and deletions.
b. All
will carry the same translocation as the father.
c. None
will carry the translocation since abnormal sperm will die.
d. His sperm will be
sterile and the couple might consider adoption.
9. In humans, male-pattern baldness is controlled by an autosomal gene
that occurs in two allelic forms. Allele Hn determines nonbaldness, and allele
Hb determines pattern baldness. In males, because of the presence of testosterone,
allele Hb is dominant over Hn. If a man and woman both with genotype HnHb have
a son, what is the chance that he will eventually be bald?
a. 0%
b. 25%
c. 75%
d. 50%
10. If nondisjunction occurs in meiosis II during gametogenesis, what will
be the result at the completion of meiosis?
a. All
the gametes will be diploid.
b. Half
of the gametes will be n + 1, and half will be n - 1.
c. 1/4
of the gametes will be n + 1, 1/4 will be n - 1, and 1/2 will be n.
d. There will be
three extra gametes
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