Name: 
 

AP CH12


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

1. 
The first, and most famous, genetics experiments were done using
a.
garden peas.
b.
fruit flies.
c.
bread mold.
d.
humans.
e.
laboratory mice.
 

2. 
Who discovered the process of meiosis?
a.
Morgan
b.
Mendel
c.
Sturtevant
d.
Weismann
e.
Flemming
 

3. 
Genes are
a.
located on chromosomes.
b.
inherited in the same way as chromosomes.
c.
arranged in linear sequence on chromosomes.
d.
assorted independently during meiosis.
e.
all of these
 

4. 
Sex chromosomes
a.
determine gender.
b.
vary from one sex to another.
c.
carry some genes that have nothing to do with sex.
d.
were unknown to Mendel.
e.
all of these
 

5. 
A karyotype
a.
compares one set of chromosomes to another.
b.
is a visual display of chromosomes arranged according to size.
c.
is a photograph of cells undergoing mitosis during anaphase.
d.
of a normal human cell shows 48 chromosomes.
e.
cannot be used to identify individual chromosomes beyond the fact that two chromosomes are homologues.
 

6. 
Which chemical is used to keep chromosomes from separating during metaphase?
a.
Giemsa stain
b.
acetone
c.
colchicine
d.
alcohol
e.
formaldehyde
 

7. 
Karyotype analysis
a.
is a means of detecting and reducing mutagenic agents.
b.
is a surgical technique that separates chromosomes that have failed to segregate properly during meiosis II.
c.
is used in prenatal diagnosis to detect chromosomal mutations and metabolic disorders in embryos.
d.
substitutes defective alleles with normal ones.
e.
all of these
 

8. 
Which of the following statements is false?
a.
The SRY gene is absent in all females.
b.
The SRY gene apparently is the gene that controls the development of male sexuality.
c.
The development of maleness is by default because males lack 2 X chromosomes.
d.
Maleness develops in the embryo before femaleness.
e.
There is no difference in external genitalia of males or females until four weeks after conception when the genes determining sex begin to be expressed.
 

9. 
Concerning the sex chromosomes, which of the following is correct?
a.
The Y chromosome carries a greater number of nonsexual traits.
b.
X and Y are different in size but carry nearly equal numbers of genes.
c.
The X chromosome carries more genes for nonsexual traits.
d.
The X chromosome carries only gender-related genes.
e.
The X chromosome carries the TDF gene.
 

10. 
In his experiments with Drosophila melanogaster, Morgan demonstrated that
a.
fertilized eggs have two sets of chromosomes, but eggs and sperm have only one set in each gamete.
b.
aneuploidy exists in karyotypes that have undergone deletions and inversions in specific chromosomes.
c.
colchicine is effective in producing polyploidy in F2 generations.
d.
certain genes are located only on an X chromosome and have no corresponding alleles on the Y chromosome.
 

11. 
Genes that are located on the same chromosome
a.
tend to be inherited together.
b.
will appear together in the gamete.
c.
are said to be linked.
d.
may be separated during synapsis and crossing over.
e.
all of these
 

12. 
Gene mapping
a.
applies only to genes located on the same chromosomes.
b.
represents actual physical distance between genes.
c.
is based upon the frequency of crossing over.
d.
can be accomplished only by using the sex chromosomes.
 

13. 
Which of the following would be the least satisfactory organism for genetic research?
a.
humans
b.
bacteria
c.
corn
d.
fruit flies
e.
peas
 

14. 
In a pedigree chart, a male showing the specific trait being studied is indicated by a
a.
darkened square.
b.
clear square.
c.
darkened diamond.
d.
clear triangle.
e.
darkened circle.
 

15. 
If a study of several pedigrees demonstrated that two parents are normal but their children express a trait, then the trait is controlled by a
a.
codominant gene.
b.
simple dominant gene.
c.
recessive gene.
d.
sex-linked gene.
e.
No conclusion can be drawn.
 

16. 
An autosomal recessive disorder
a.
requires that only one parent be a carrier.
b.
displays its symptoms only in heterozygotes.
c.
is more frequent in males than females.
d.
will appear only in children of parents who both carry the gene.
e.
is dominant in females.
 

17. 
The probability of producing a normal child by two parents who are carriers for an autosomal recessive disorder is
a.
50 percent.
b.
0 percent.
c.
100 percent.
d.
25 percent.
e.
75 percent.
 

18. 
Males tend to be affected in greater numbers by X-linked recessive genetic disorders than are females because
a.
females have two dominant genes for the disorder.
b.
males have only one recessive gene for the disorder.
c.
males have a double dose of the gene.
d.
Y chromosomes are not as strong as X chromosomes.
 

19. 
Red-green color blindness is an X-linked recessive trait in humans. A color-blind woman and a man with normal vision have a son. What is the probability that the son is color blind?
a.
100 percent
b.
75 percent
c.
50 percent
d.
25 percent
e.
0 percent
 

20. 
What could the children of a color-blind woman and a man with normal vision be?
a.
All will be color blind.
b.
None will be color blind.
c.
Daughters will be color blind and sons will be normal.
d.
Sons will be color blind and daughters will be normal.
 

21. 
A chromosome's gene sequence that was ABCDEFG before modification and ABCDLMNOP afterward is an example of
a.
inversion.
b.
deletion.
c.
duplication.
d.
translocation.
e.
aneuploidy.
 

22. 
A chromosome's gene sequence that was ABCDEFG before modification and ABCDCDEFG afterward is an example of
a.
inversion.
b.
deletion.
c.
duplication.
d.
translocation.
e.
aneuploidy.
 

23. 
Chromosomal aberrations can be produced by exposure to
a.
viruses.
b.
radiation.
c.
various chemicals.
d.
viruses and radiation, only.
e.
viruses, radiation, and various chemicals.
 

24. 
A chromosome's gene sequence that was ABCDEFG before damage and ABCFG after is an example of
a.
inversion.
b.
deletion.
c.
duplication.
d.
translocation.
e.
aneuploidy.
 

25. 
A chromosome's gene sequence that was ABCDEFG before damage and ABFEDCG after is an example of
a.
inversion.
b.
deletion.
c.
duplication.
d.
translocation.
e.
aneuploidy.
 

26. 
The condition occurring when an organism has a 2n + 1 chromosome composition is known as
a.
monosomy.
b.
deletion.
c.
diploid.
d.
aneuploidy.
e.
both deletion and aneuploidy.
 

27. 
If a gamete is missing one chromosome,
a.
the chromosome number is expressed as 2n - 1.
b.
then one chromosome is without its homologue.
c.
the condition is called monosomy.
d.
only the chromosome number is expressed as 2n - 1, and the condition is called monosomy.
e.
only the chromosome number is expressed as 2n - 1, one chromosome is without its homologue, and the condition is called monosomy.
 

28. 
If nondisjunction occurs during meiosis,
a.
the resulting sex cells will be heterogametes.
b.
one-half of the resulting cells will exhibit trisomy and the other half monosomy.
c.
diploid cells will be produced.
d.
all gametes would lack a chromosome and these gametes would be infertile.
 

29. 
The failure of chromosomes to separate during mitosis or meiosis is called
a.
genetic displacement.
b.
trisomy.
c.
crossing over.
d.
nondisjunction.
e.
disjunction.
 

30. 
Down syndrome involves trisomy
a.
3.
b.
5.
c.
15.
d.
19.
e.
21.
 

31. 
Syndrome means
a.
a chromosome disorder.
b.
a simple genetic disease.
c.
a set of symptoms that occur together.
d.
an incurable disease.
e.
a rare inborn defect.
 

32. 
Which of the following conditions is characterized by a karyotype with 45 chromosomes?
a.
Turner syndrome
b.
Down syndrome
c.
testicular feminization syndrome
d.
Klinefelter syndrome
e.
cri-du-chat
 

33. 
Nondisjunction involving the X chromosomes may occur during oogenesis and produce two kinds of eggs. If normal sperm fertilize these two types, which of the following pairs of genotypes are possible?
a.
XX and XY
b.
XXY and XO
c.
XYY and XO
d.
XYY and YO
e.
none of these
 

34. 
Which of the following designates a normal human male?
a.
YY
b.
XX
c.
XY
d.
XO
e.
XYY
 

35. 
A genetic abnormality that may result in sterile males with mental retardation or breast enlargement is
a.
XXY.
b.
XYY.
c.
Turner syndrome.
d.
Down syndrome.
e.
none of these
 

36. 
Aneuploidy would describe all of the following except
a.
Turner syndrome.
b.
Klinefelter syndrome.
c.
translocation.
d.
XYY.
e.
Down syndrome.
 

37. 
Phenotypic treatments for genetic disorders include
a.
preventing the disorders in the carriers.
b.
eliminating the defective gene.
c.
preventing a disorder from being passed on.
d.
preventing a disorder from being expressed.
e.
all of these
 

38. 
PKU can be detected by
a.
karyotyping.
b.
urine analysis.
c.
blood tests.
d.
saliva tests.
e.
both urine analysis and blood tests.
 

39. 
Amniocentesis is
a.
a surgical means of repairing deformities.
b.
a form of chemotherapy that modifies or inhibits gene expression or the function of gene products.
c.
used in prenatal diagnosis to detect chromosomal mutations and metabolic disorders in embryos.
d.
a form of gene replacement therapy.
e.
all of these
 

40. 
The most recent technique for analyzing the genetics of the unborn child involves the sampling of
a.
the fetus directly.
b.
cells in the amniotic fluid.
c.
material from the allantois.
d.
the chorionic villi.
e.
yolk sac material.
 

Short Answer
 
 
Number of Chromosomes

Answer the following questions in reference to the five items listed below.
a.      12
b.      23
c.      24
d.      46
e.      47
 

41. 
Refer to Number of Chromosomes. How many chromosomes are present in the somatic cells of a child born with Down syndrome (trisomy 21)?
 

42. 
Refer to Number of Chromosomes. The normal sperm cell of species X carries 11 chromosomes. Following nondisjunction in the formation of secondary spermatocytes and their subsequent fertilization of normal ova, some of the zygotes will have 21 chromosomes, others will have 22, and the remainder will have how many chromosomes?
 
 
Five Different Processes

Answer the following questions in reference to the five processes listed below. Note that to answer these questions you need to know that the sequence of amino acids directly reflects the sequence of genes that coded for their placement.
a.      an inversion
b.      a deletion
c.      a gene duplication
d.      a translocation
e.      an addition
 

43. 
Refer to Five Different Processes. Homologous sets of genes ABCDEF and AEDCBF are located on homologous chromosomes. Crossing over between them is suppressed because of this.
 
 
Five Disorders

Answer the following questions in reference to the five disorders listed below:
a.      galactosemia
b.      Turner syndrome
c.      AIDS
d.      hemophilia
e.      Down syndrome
 

44. 
Refer to Five Disorders. For this disorder, both a phenotypic cure and a genotypic cure are potentially possible.
 
 
Five Methods

Answer the following questions in reference to the five items listed below:
a.      surgical correction
b.      chemotherapy
c.      genetic screening
d.      genetic counseling
e.      gene therapy
 

45. 
Refer to Five Methods. The substitution of a normal allele for a defective allele via the methods of genetic engineering would be an example of this.
 



 
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