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Chapter 15



Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 

Which of the following statements is (are) true?
a.
The closer two genes are on a chromosome, the higher the probability that a crossover will occur between them.
b.
The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 50%.
c.
Two of the traits that Mendel studied-seed color and flower color-are linked on the same chromosome.
d.
Only B and C are correct.
e.
A, B, and C are correct.
 

 2. 

A 0.1% frequency of recombination is observed
a.
only in sex chromosomes.
b.
only on genetic maps of viral chromosomes.
c.
on unlinked chromosomes.
d.
in any two genes on different chromosomes.
e.
in genes located very close to one another on the same chromosome.
 

 3. 

What is the mechanism for the production of genetic recombinants?
a.
X inactivation
b.
methylation of cytosine
c.
crossing over and independent assortment
d.
nondisjunction
e.
deletions and duplications during meiosis
 
 
X, Y, and Z are three genes in Drosophila. The recombination frequencies for two of the three genes are shown below.

chpt15_files/i0050000.jpg
 

 4. 

Genes X and Y could be
a.
located on different chromosomes.
b.
located very near to each other on the same chromosome.
c.
located far from each other on the same chromosome.
d.
both A and B
e.
both A and C
 

 5. 

In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?
a.
tortoiseshell female; tortoiseshell male
b.
black female; orange male
c.
orange female; orange male
d.
tortoiseshell female; black male
e.
orange female; black male
 

 6. 

Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?
a.
XcXc and XcY
b.
XcXc and XCY
c.
XCXC and XcY
d.
XCXC and XCY
e.
XCXc and XCY
 

 7. 

In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A lethal recessive allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a normal female?
a.
2:1 male to female
b.
1:2 male to female
c.
1:1 male to female
d.
4:3 male to female
e.
3:1 male to female
 

 8. 

Male calico cats could be the result of
a.
sex-linked inheritance.
b.
nondisjunction, leading to the male calico having two X chromosomes.
c.
incomplete dominance of multiple alleles.
d.
recessive alleles retaining their fundamental natures even when expressed.
e.
a reciprocal translocation.
 

 9. 

The figure below represents the stained nucleus from a cheek epithelial cell of an individual whose genotype would probably be

chpt15_files/i0110000.jpg

a.
XX.
b.
XY.
c.
XYY.
d.
XXX.
e.
XXY.
 

 10. 

In the following list, which term is least related to the others?
a.
trisomic
b.
monosomic
c.
aneuploid
d.
triploid
e.
nondisjunction
 

 11. 

One possible result of chromosomal breakage can be that a fragment reattaches to the original chromosome in a reverse orientation. This is called
a.
disjunction.
b.
translocation.
c.
deletion.
d.
inversion.
e.
aneuploidy.
 

 12. 

The karyotype shown below is associated with which of the following genetic disorders?

chpt15_files/i0140000.jpg

a.
Turner syndrome
b.
Down syndrome
c.
Klinefelter syndrome
d.
hemophilia
e.
male-pattern baldness
 

 13. 

In humans, male-pattern baldness is controlled by a 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.
33%
d.
50%
e.
75%
 

 14. 

Which of the following statements about mitochondria is false?
a.
Because of the role of the mitochondria in producing cellular energy, mitochondrial diseases often affect the muscles and nervous system.
b.
Because mitochondria are present in the cytoplasm, mitochondrial diseases are transmitted maternally.
c.
Like nuclear genes, mitochondrial genes usually follow Mendelian patterns of inheritance.
d.
Mitochondria contain circular DNA molecules that code for proteins and RNAs.
e.
Many mitochondrial genes encode proteins that play roles in the electron transport chain and ATP synthesis.
 



 
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