Name: ________________________________
Section MC, SD
Dr. Ippolito’s BIO-121 Spring 2008
Test 5 (Mendel, Chromosomes, and DNA)
Please make sure you have 9 pages / 60 questions.
1. Assume that having three nostrils is inherited as a Y-linked trait. A man with three nostrils has a
daughter who has a son with a man who has only two nostrils. What is the probability that the threenostriled man's grandson has three nostrils?
a. 0%
b. 25%
c. 50%
d. 75%
e. 100%
2. Who is credited for discovering the structure of DNA?
a. Pauling
b. Watson and Crick
c. Chase
d. Franklin
e. Hershey and Chase
3. What type of chemical bond joins the bases of complementary DNA strands?
a. ionic
b. nonpolar covalent
c. hydrophobic
d. polar covalent
e. hydrogen
4. Unattached earlobes (EE or Ee) are dominant over attached earlobes (ee). A couple both have
unattached earlobes. One parent on each side of the family has attached earlobes (ee). Therefore,
they correctly assume that they are carriers for attached earlobes (Ee). The couple proceed to have
four children.
a. They can be certain that three will be heterozygous and one homozygous recessive.
b. If the first three are heterozygous, the fourth must be homozygous recessive.
c. The children must repeat the grandparents' genotype (Ee).
d. All children must have unattached earlobes since both parents possess the dominant gene for it.
e. Two heterozygous, one homozygous recessive and one homozygous dominant is a likely
outcome, but all heterozygous, or two, three or all four homozygous are also possible.
5. Which of
a.
b.
c.
d.
e.
the following human genetic disorders is NOT caused by nondisjunction?
Down's syndrome
Turner's syndrome
Klinefelter syndrome
Fragile X syndrome
Fragile Y syndrome
6. Chorionic villus sampling uses what tissue to analyze the fetal cells and provide a karyotype?
a. fetal blood tissue
b. cells floating in the amniotic fluid
c. a small biopsy from the embryo itself but it readily heals
d. membrane tissues from the embryo side of the placenta
e. membrane tissues from the mother's side of the placenta
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7. Which refers to the movement of a piece of one chromosome to another nonhomologous
chromosome?
a. Inversion
b. Translocation
c. Deletion
d. Duplication
e. Monosomy
8. What additional chromosomal abnormalities will likely result from a chromosomal inversion?
a. Additional inversions
b. Deletions only
c. Duplications only
d. Duplications and Deletions
e. Nondisjunction
9. A human male has ____ chromosomes with ____ sex chromosomes.
a. 46, XY
b. 23, XY
c. 46, XX
d. 23, XX
e. 46, YY
10. What is the most typical cause of Down’s Syndrome?
a. The individual has only a single chromosome when they should have two (they are monosomy)
b. The individual has a small piece of one chromosome attach to another (a translocation occurred)
c. The individual has three copies of a chromosome when they should have two copies (they are
diploid)
d. They are trisomy for chromosome 21
e. They are monosomy for chromosome 21
11. Which statement is FALSE about X-linked characteristics?
a. More males than females are affected.
b. If a female has the characteristic, all her sons will show it.
c. Females can be carriers of the gene without showing it.
d. The characteristic often skips a generation, from a woman's father to her son.
e. Males can have two copies of the alleles for the trait, but females can have only one.
12. Karyotyping can be used to diagnose which of the following genetic disorders?
a. Down syndrome
b. color-blindness
c. muscular dystrophy
d. hemophilia
e. All of the choices.
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13. Colchicine is a drug used to prepare cells for karyotyping. Given your knowledge of karyotyping and
the cell cycle, which is the most likely mechanism of this drug?
a. inhibits microtubule depolymerization
b. inhibits chromosomal deletions and insertions
c. inhibits cytokinesis
d. inhibits chromosome condensation
e. inhibits crossing over of nonsister chromatids
14. If nondisjunction occurs during meiosis I…
a. the resulting sex cells are heterogametes.
b. one-half of the resulting cells are n + 1 and the other half are n - 1.
c. diploid cells are produced.
d. all gametes will lack a chromosome and be infertile.
e. only one half the gametes are affected.
15. Aneuploidy describes all of the following except
a.
b.
c.
d.
e.
Turner syndrome.
Klinefelter syndrome.
translocation.
XYY.
Down syndrome.
16. If a DNA sample contains 13% adenine, what percentage of the sample contains cytosine?
a. 13%
b. 37%
c. 26%
d. 74%
e. 87%
17. A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring. What is the
recombination frequency for the two gene pairs?
a. 6%
b. 3%
c. 30%
d. 1.5%
e. 0.5%
18. A general evolutionary trend is that the more complex an organism, the more functional
genes they have. However, chromosome number varies greatly: ants have 2, molds have 814, we have 46, potatoes have 100, while crayfish have 200. Some birds and insects have
chromosomes that are so short, they are too small to establish an actual diploid number.
This means that….
a. There’s no relationship between the amount of genetic information and complexity.
b. The number of genes per chromosome can vary amongst organisms, which prevents a
simple relationship between chromosome # and complexity to be established.
c. Birds and insects follow different laws of mitosis than other organisms.
d. The more genes an organism has, the more chromosomes it will have.
e. All of these are true
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19. Women with X-linked disorders always pass the genes for the disorder to ______, while men with Xlinked disorders always pass the genes for the disorder to _______.
a. only their daughters; only their daughters
b. both their daughters and sons; only their sons
c. both their daughters and sons; only their daughters
d. both their daughters and sons; their daughters and sons
e. both their daughters and sons; their daughters only
20. If a woman is a carrier for the color-blind recessive allele and her husband is normal, what are their
chances that a son will be color-blind?
a. None since the father is normal.
b. 50% since the mother is the only carrier.
c. 100% because the mother has the gene.
d. 25% because the mother is a hybrid.
e. None since he will also be just a carrier.
21. Assume your parents have blood types A and B respectively, but you do not know if they are
homozygous or heterozygous. At the next family reunion, you get out a notepad and draw a pedigree
chart. Whose blood types would provide possible clues to your parents' genotypes?
a. your grandparents
b. those aunts and uncles that are your parents siblings, especially if your grandparents are not
alive
c. your brothers and sisters
d. you
e. all of the choices are correct.
22. The X-ray diffraction photography of Rosalind Franklin was essential for…
a. Indicating that DNA’s structure is a double helix.
b. Showing equal numbers of purines and pyrimidines.
c. Showing the bases of DNA were held together by hydrogen bonds.
d. Revealing the structure of the deoxyribose sugar.
e. Of the location of each adenine, guanine, cytosine, and thymine.
23. DNA was clearly demonstrated to be the transforming factor in bacterial cells in experiments by
a. Meischer.
b. Watson and Crick.
c. Griffith.
d. Franklin
e. Hershey and Chase
24. In the Watson and Crick model of DNA, the "steps" of the ladder are composed of
a. sugars.
b. a purine and a pyrimidine.
c. two purines.
d. two pyrimidines.
e. a sugar and a phosphate molecule.
25. When we refer to the ‘backbone’ of DNA, what are we referring to?
a. The repeating nitrogenous bases
b. The sugar-nucleotide-suger-nucleotide pattern
c. The sugar-phosphate-sugar-phosphate pattern
d. The base-pairing of A:T and C:G
e. The bonds connecting the two strands.
26. RNA utilizes ______, whereas DNA contains ______
a. Deoxyribose sugar…ribose sugar.
b. Nucleotides … nucleic acid
c. Uracil… thymine
d. Cytosine…guanine
e. Adenine… guanine
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27. Assume DNA replication is NOT semi-conservative. Meselson and Stahl's replication experiment
would have shown different results. After growing the bacteria first on heavy 15N, centrifuged results
would have shown one band of heavy DNA. If then bacteria were allowed to grow on light 14N, the
centrifuged results would have shown:
a. One hybrid band and one light band.
b. One heavy band and one light band.
c. Two heavy bands.
d. One hybrid band and one heavy band.
e. Two light bands.
28. Which of the following statements about DNA replication is FALSE?
a. Unwinding of the DNA molecule occurs as hydrogen bonds break.
b. Replication occurs as each base is paired with another exactly like it.
c. The process is known as semiconservative replication because one old strand is conserved in the
new molecule.
d. The enzyme that catalyzes DNA replication is DNA polymerase.
e. Complementary base pairs are held together with hydrogen bonds.
29. Because one original strand of the double-stranded helix is found in each daughter cell, the
replication process is called
a. proofreading.
b. semiconservative.
c. redundant.
d. freeing of DNA.
e. mutation positive.
30. Which does NOT describe a function of the DNA polymerase molecule?
a. recognize the free nucleotide that pairs with the base on the template strand of DNA
b. read the strand of template DNA and recognize the specific base at a particular location within the
strand
c. proofread to ensure that the proper base has been incorporated
d. synthesize the proper nucleotide to match with the base read on the template strand
e. cut out an improperly paired nucleotide and replace it with the proper one
31. With your knowledge of Chargaff’s Rules, which of the following mathematical equations must be
true?
a. A + T = G + C.
b. A + G = T + C.
c. A = G, T = C.
d. A = C, T = G.
e. All of these are true.
32. Avery and his group knew that either proteins or DNA had to be the source of genetic material. Which
of the following of their experiments directly supports the hypothesis that DNA, not protein, is in fact
the hereditary material?
a. The S strain transformed the R strain
b. Neither proteases nor RNases prevent transformation
c. DNase prevents transformation
d. The size of the transforming substance was huge
e. All of these directly support DNA as the hereditary material
33. Which of the following is/are NOT true about mutations?
a. Damage to DNA can result after exposure to environmental factors such as sunlight or chemicals
such as pesticides.
b. Mutations can often be repaired by cellular enzymes.
c. Mutations to DNA always result in lethal effects and therefore death of a cell.
d. Variations in DNA and mutations are important for evolution to occur.
e. All of these statements are true of DNA.
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34. Which is NOT a difference between prokaryotic and eukaryotic DNA replication?
a. Prokaryotic DNA replication is unidirectional; eukaryotic is bidirectional
b. Prokaryotic DNA lets U pair with A; eukaryotic DNA only allows A to pair with T.
c. Prokaryotic DNA polymerase is faster at replicating DNA than Eukaryotic DNA polymerase.
d. Prokaryotic DNA replication is much more error prone than Eukaryotic DNA replication
e. All of these are differences between prokaryotic and eukaryotic DNA replication.
35. Which of the following represents the set of all possible gametes from AABb ?
a. AB, Ab
b. AA, Bb
c. AB, Ab, aB, ab
d. AB, Ab, AA, Bb
e. A, A, B, b
36. In the use of a Punnett square for genetic results of crossing individuals
a. all different kinds of sperm are lined up either horizontally or vertically.
b. all different kinds of eggs are lined up either horizontally or vertically.
c. every possible allele combination is placed within the square.
d. the results show the offspring's expected genotypes.
e. All of the choices are correct.
37. Which of the following are TRUE statements about the nature of DNA structure & function?
a. DNA is replicated from the 3’ to the 5’ end, with new nucleotides added to the 5’ end.
b. DNA is replicated from the 5’ to the 5’ end, with new nucleotides added to the 3’ end.
c. DNA replication results in two new DNA double helices.
d. Two of the above are correct.
e. None of the above are correct.
38. Which is NOT a difference between prokaryotic and eukaryotic DNA replication?
a. Prokaryotic DNA replication is unidirectional; eukaryotic is bidirectional
b. Prokaryotic DNA lets U pair with A; eukaryotic DNA only allows A to pair with T.
c. Prokaryotic DNA polymerase is faster at replicating DNA than Eukaryotic DNA polymerase.
d. Prokaryotic DNA replication is much more error prone than Eukaryotic DNA replication
e. All of these are differences between prokaryotic and eukaryotic DNA replication.
39. Which is FALSE according to Mendel's law of segregation?
a. Each individual contains two factors for each trait.
b. One factor must be dominant and one factor recessive in each individual.
c. Factors separate from each other during gamete formation.
d. Each gamete contains one copy of each factor.
e. Fertilization restores the presence of two factors.
40. Consider the case of a lethal recessive gene located on the human X-chromosome; it is therefore sexlinked. Its effect is to prevent the full development of the embryo, which therefore is reabsorbed by
the body at an early stage. Beginning with a female who carries this gene in a heterozygous state,
what proportion of the viable offspring will be female?
a. one-half
b. two-thirds
c. three-fourths
d. all, because the lethal recessive gene will express itself in the absence of any genes on the short
Y-arm for the XY male embryos
e. No offspring will be produced at all.
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41. If the probability of event A is 3/4 and the probability of event B is 1/4, then the probability of both A
and B occurring at the same time is
a. 3/4.
b. 1/4.
c. 1 or absolute certainty.
d. 4/8 (or just ½)
e. 3/16.
42. Which “inconvenience” prevents DNA replication from looking like a well-designed mechanism?
a. The strands are arranged parallel to each other – The end of each strand would have the 5’
carbons next to each other, and at the other end, the 3’ carbons next to each other.
b. The strands are arranged anti-parallel to each other – the 5’ and 3’ ends of each strand face
opposite directions
c. DNA polymerase moves very, very slowly
d. DNA polymerase has the ability to proofread, allowing the error rate to be as low as 1 in a billion
under standard conditions
e. DNA replication is semi-conservative.
We will NOT have time to go over this test today; hand in both the test booklet and the
scan-tron when you are finished.
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