Sample Questions, Exam III
1.
Snapdragons have a sincle gene (locus) that determines flower color. The
allele R is for red flowers and it shows incomplete dominance over the
recessive allele r for white flowers. What color flowers are produced by Rr
plants?
a.
All red
b.
Mixed red and white (some flowers of each color)
c.
pink
d.
white with pink streaks
e.
purple
2.
An allele at one locus affects several phenotypic traits (e.g. cystic fibrosis
is caused by a single defective gene which causes clogged blood vessels,
sticky mucus, salty sweat, liver failure, etc.). This is an example of:
a.
continuous variation.
b.
codominance.
c.
incomplete dominance.
d.
epistasis.
e.
pleiotropic effects.
3.
A human is heterozygous at a blood group locus and expresses both genotypes
(e.g. they have type AB blood). This is an example of:
a.
polygenic inheritance.
b.
codominance.
c.
incomplete or partial dominance.
d.
pleiotropy.
e.
complete dominance.
4.
Occasionally, a gene at one chromosomal locus affects the phenotypic
expression of a second gene found at an entirely different chromosomal locus.
This phenomenom is called:
a.
pleiotropy.
b.
partial dominance.
c.
epistasis.
d.
secondary regulation.
e.
polygenic inheritance.
5.
An example of a sex-linked human genetic-based disorder is:
a.
Duchene muscular dystrophy.
b.
sickle cell anemia.
c.
HuntingtonÕs disease.
d.
cystic fibrosis.
e.
Tay-Sachs disease.
Genes located on the same chromosome are said to be:
a.
polygenic.
b.
bottlenecked.
c.
pleiotropic.
d.
linked.
e.
epistatic.
6.
7.
A human autosomal recessive lethal genetic disease whose defective allele has
been maintained at a relatively high level in certain population groups
because it gives the heterozygote resistance to an infectious disease is:
a.
Tay-Sachs disease.
b.
cystic fibrosis.
c.
sickle-cell anemia.
d.
muscular dystrophy.
e.
HuntingtonÕs disease.
_______________________________________________________________________
8.
Four genes (A, W, E, and G) on a chromosome have the following linkage map:
The lowest recombination frequency would be observed between genes:
a.
A and W.
b.
W and E.
c.
E and G.
d.
A and E.
e.
A and G.
_______________________________________________________________________
9.
Thomas Morgan was
a.
b.
c.
d.
e.
the first person to:
map a specific gene/trait to a specific chromosome.
observe codominance.
carry out amniocentesis.
observe crossing over under the microscope.
define genetic variation.
10.
An example of a human genetic condition caused by an autosomal dominant
defective gene/allele:
a.
KlinefelterÕs syndrome.
b.
Down syndrome.
c.
HuntingtonÕs disease.
d.
cystic fibrosis.
e.
Turner.
11.
An inactivated ÒXÓ chromosome in a human female cell is seen as a/an:
a.
centrosome.
b.
Barr body.
c.
genetic imprint.
d.
nucleosome.
e.
centromere.
12.
An early theory explaining the basis of evolution suggested organisms could
alter their phenotype by use or disuse of a character (stretch the neck, for
example) and that such aquired characteristics could be passed on to the
following generation. The scientist best known for this theory was:
a.
Lamarck.
b.
Mendel.
c.
Morgan.
d.
Darwin.
e.
Barr.
13.
The primers for DNA synthesis in E. coli cells are:
a.
short segments of DNA which contain many errors.
b.
special proteins called primases.
c.
short RNA molecules.
d.
synthesized by reverse transcriptase.
e.
E. coli DNA polymerase does not require a primer.
14.
An example of a human genetic disease involving a male with a
a.
Klinefelter syndrome.
b.
Down syndrome.
c.
HuntingtonÕs disease.
d.
Turner syndrome
e.
muscular dystrophy.
Barr body is:
15.
The human chromosomes which are not either the "X" or "Y" chromosomes are
collectively called _________.
a.
mosaics
b.
sex chromosomes
c.
karyotypes
d.
monosomics
e.
autosomes
16.
A human gene is said to be sex-linked if:
a.
it is more common in females than males.
b.
it is found on the ÒYÓ chromosome.
c.
it is encoded by the ÒXÓ chromosome.
d.
it is expressed only in males.
e.
it is recessive in males.
17.
The structure shown to the right is an example of a:
A.
purine.
B.
pyrimidine.
C.
ribose sugar.
D.
deoxyribose sugar.
E.
molecule not found in DNA.
18.
Which of the following is not a source of microevolution?
a.
genetic drift
b.
mutation
c.
random mating
d.
natural selection
e.
All of the above are sources of microevolution.
19.
All of the following conditions are requirements for maintaining HardyWeinberg equilibrium in a population EXCEPT:
A.
random mating.
B.
no migration.
C.
a high net mutation rate.
D.
large population size.
E.
no natural selection.
20.
Throughout history, the migration of people on Earth has steadily increased.
This movement has changed human evolution by increasing the:
a.
nonrandom mating.
b.
bottleneck effect.
c.
genetic drift.
d.
mutation rate.
e.
gene flow.
21.
Two males and two females are the first colonists on Mars. After many
generations, the population of Mars has a high allele frequency for color
blindness. This is most likely due to:
a.
the bottleneck effect.
b.
gene flow.
c.
assortative mating.
d.
the founder effect.
e.
mutation.
22.
The red flower allele exhibits incomplete dominance over the white flower
allele. Using the Hardy-Weinberg equation (p2 + 2pq + q2 = 1), if the
frequency of the red allele in a popopulation is 0.8 and the frequency of the
white allele is 0.2, what is the fraction of plants which will have pink
flowers?
a.
4%
b.
8%
c.
16%
d.
32%
e.
64%
23.
During DNA replication, the "lagging strand" is synthesized as a series of
small DNA fragments which are later connected into a continuous DNA molecule.
These short segments are called :
a.
Okazaki fragments.
b.
replicons.
c.
replication forks.
d.
transcription units.
e.
Griffith units.
24.
The enzyme which unwinds the DNA helix, allowing replication to occur is
called:
a.
primase.
b.
DNA replicase.
c.
reverse transcriptase.
d.
helicase.
e.
DNA litigase.
25.
The DNA from cells grown many generations in 14N medium and then switched to
15N medium for one generation would give a pattern after CsCl gradient
centrifugation looking like:
(a)
(b)
(c)
(d)
(e)
____________________________________________________________________________
26.
DNA replication in bacteria occurs by a _____________ mechanism as
demonstrated by the experiment of ___________.
a.
semi-conservative, Chargaff
b.
c.
d.
e.
conservative, Messelson and Stahl
dispersive, Avery and Mcleod
semi-conservative, Messelson and Stahl
conservative, Watson and Crick
27.
The enzyme which covalently connects the short DNA fragments synthesized on
the lagging strand (i.e. "ties" them together) is called:
a.
DNA nuclease.
b.
DNA polymerase.
c.
helicase.
d.
DNA ligase.
e.
primase.
28.
The enzyme which extends the primers, making the new DNA strand at the
replication fork is:
a.
DNA polymerase I.
b.
primase.
c.
RNA polymerase.
d.
DNA replicase.
e.
DNA polymerase III.
29.
Okazaki is best known for:
a.
his experiments which showed DNA replication occurs in a
semiconservative manner.
b.
his experiments which showed tha DNA is the genetic
material.
c.
his experiments which showed that genes encode proteins.
d.
his experiments which showed the direction of DNA synthesis.
e.
his experiments which showed DNA on the lagging strand of a
replication fork is synthesized in short pieces.
30.
Griffith used rodents and strains of Streptococcus pneumoniae (the bacterial
species he used were at that time known as Pneumococcus) to demonstrate:
a.
that DNA is the genetic material.
b.
DNA replication occurs semiconservatively.
c.
bacterial transformation.
d.
protein coats of bacteriophage are not required for
successful infection.
e.
German bombs can adversely affect experimental results.
The structure of DNA molecules was first elucidated by:
a.
Watson and Crick.
b.
Avery.
c.
Franklin and Wilkins.
d.
Griffith.
e.
Beadle and Tatum.
31.
32.
Alfred Hershey and Martha Chase used 32P and 35S radioactively-labeled
bacteriophage show that:
a.
DNA can be selectively labeled by 35S atoms.
b.
bacteriophage proteins can be specifically labeled by 32P.
c.
entry of bacteriophage proteins into the bacterium
correlated well with the subsequent production of progeny
bacteriophage.
d.
DNA is the genetic material of T2 bacteriophage.
e.
the phospholipid membrane of bacteriophage does not transfer
genetic material from one generation to the next.
33.
Which of the following is NOT true of the presently accepted model for the
structure of DNA?
a.
It is a double helix.
b.
The two strands are antiparallel.
c.
The bases are located on the interior of the helix.
d.
The two strands are complementary.
e.
All of the above are true of this model for DNA structure.
34.
The experiment by Avery (using the method of Griffith) utilized which of the
following to demonstrate that DNA is the genetic material?
a.
Cesium chloride (CsCl), ultracentrifugation, 14N, 15N, E.
coli
b.
32P, 35S, T2 bacteriophage, E. coli
c.
TMV virus, RMV virus, tobacco plants
d.
Pneumococcus, DNase, RNase, protease, lipase (digests
lipids)
e.
X-ray crystallography
35.
Chargaff’s studies lead him to conclude:
a.
that the amount of adenine (A) in the DNA from an organism
always equaled the amount of thymine (T) in the DNA from the
same organism.
b.
that DNA was a helix.
c.
that the lactose operon was inducible.
d.
that DNA was in fact the genetic material responsible for
bacterial transformation.
e.
he should have gone to medical school and made real money.
36.
The whooping crane population fell to less than 2 dozen individuals earlier in
this century. From the point of population genetics, this group of
individuals might be expected to show substantial evidence of:
a.
natural selection.
b.
pleitrophy.
c.
the bottleneck effect.
d.
Only answers ÒaÓ and ÒcÓ are likely to be true.
e.
All of the above are likely to be true.
37.
The X-ray crystallography pictures critical to the discovery of the structure
of DNA were obtained by:
a.
Franklin and Wilkins.
b.
Watson and Crick.
c.
Avery and Griffith.
d.
Beadle and Tatum.
e.
Messelson and Stahl.
38.
The individual nucleotides which make up a single strand of DNA are connected
to the nucleotides above and below them (or to the 5Õ and 3Õ sides if you
prefer--NOT CONNECTING TWO STRANDS OF THE DUPLEX to each other) by:
a.
peptide bonds.
b.
hydrogen bonds.
c.
phosphodiester bonds.
d.
reversible bonding.
e.
faith.
39.
In a DNA duplex, the base A is always paired with:
a.
guanine.
b.
cytosine.
c.
d.
e.
thymine.
uracil.
deoxyribose.
40.
The base pairs between two strands of a DNA molecule are held together by:
a.
phosphodiester bonds.
b.
ionic bonds involving the phosphate groups.
c.
polar covalent bonds.
d.
hydrogen bonds.
e.
a combination of all of the above.
41.
DNA polymerases do NOT require which of the following in order to synthesize
new DNA?
a.
a primer
b.
a template
c.
deoxyribonucleotide triphosphates (dNTPs)
d.
ATP
e.
All of the above are required by DNA polymerases.
42.
The protein that keeps the single-stranded DNA from rewinding at the
replication fork during
DNA replication is:
a.
DNA polymerase III.
b.
primase.
c.
ssb.
d.
helicase.
e.
DNA ligase.
43.
The location on a chromosome where DNA replication begins is called a/an:
a.
origin (ori).
b.
promoter.
c.
centromere.
d.
telomere.
e.
initiator.
44.
The scientist(s) who generated and characterized auxotrophic mutants of
Neurospora to demonstrate that a gene gives rise to a single enzyme (really
polypeptide) was/were:
a.
Watson and Crick.
b.
Fraenkle and Conrad.
c.
Abbot and Costello.
d.
Beadle and Tatum.
e.
Garrod
45.
A population of flowers has a range of colors from white to pink to dark red.
Deer eat the lighter colored plants to the point where their numbers are
reduced in the population, giving the population a darker average color. This
would be an example of:
a.
stabilizing selection.
b.
directional selection.
c.
diversifying selection.
d.
random selection.
e.
frequency-dependent selection.
46.
The scientist credited with first proposing the chromosome theory of
inheritance was:
a.
Garrod.
b.
c.
d.
e.
Sutton.
Ingram.
Sanger.
Mendel.
47.
The enzyme which removes the primers during DNA replication is:
a.
primase.
b.
DNA polymerase III (DNAP III).
c.
gyrase.
d.
DNA polymerase I (DNAP I).
e.
helicase.
48.
Which of the following carries out proofreading during DNA replication?
a.
DNA polymerases.
b.
helicases.
c.
gyrases.
d.
Ssb.
e.
primases.
49.
A human with the XXY karotype is:
a.
phenotypically a male and no Barr body.
b.
phenotypically female.
c.
phenotypically male but with a Barr body.
d.
phenotypically female with no Barr body.
e.
frequency-dependent selection.
50.
An example of a phenotypic female human with no Barr body would be someone
with:
a.
an XXX karyotype.
b.
Down Syndrome.
c.
Kleinfelter Disease.
d.
Huntington Disease.
e.
Turner Syndrome.
51.
A person with a karyotype of trisomy 21 will suffer from:
a.
Tay-Sachs.
b.
Down Syndrome.
c.
Kleinfelter Disease.
d.
Huntington Disease.
e.
Turner Syndrome.
52.
The scientist(s) who first developed a method for determining the
sequence/order of amino acids in a protein (e.g. insulin) was/were:
a.
Watson and Crick.
b.
Garrod.
c.
Hammerling.
d.
Ingram.
e.
Sanger.
53.
Proofreading by a DNA polymerase
a.
the connecting
process.
b.
the removal of
c.
the process of
d.
the removal of
activity.
describes:
of the correct bases by the polymerization
RNA primers by the 5Õexonuclease activity.
forming the new hydrogen bonds between bases.
improperly paired bases by the 3Õexonuclease
e.
the process by which DNA polymerases always get an ÒAÓ for
on eplication exams.
54.
The segment of DNA replicated from a single start point (the unit of DNA
replication, 1 per bacterial chromosome) is called a/an:
a.
centrosome.
b.
replisome.
c.
replicon.
d.
gene.
e.
cistron.
55.
A trait shows continuous variation within a population (e.g.
humans). This suggests that the trait exhibits:
a.
a polygenic pattern of inheritance.
b.
pleiotrophy.
c.
incomplete dominance.
d.
codominance.
e.
linkage disequilibrium.
height in