Download Biology 303 EXAM II 3/14/00 NAME

BIOL. 303 EXAM II 10/26/07
--------------------------------------------------------------------------------------------------------------------This exam consists of 40 multiple choice questions worth 2.5 points each. On
the separate answer sheet, please fill-in the single best choice for each question.
Please bubble-in your name on the answer sheet, leaving a space between first
and last names. Also, bubble-in the last 5 digits of your social security number
under “ID NUMBER” beginning in the left-most column. Good luck!
--------------------------------------------------------------------------------------------------------------------1.
In humans, the genetic basis for determining the sex “male” is accomplished by
A. the Y chromosome
B. the presence of only one X chromosome
C. a balance between the number of X chromosomes and the number of haploid
sets of autosomes
D. multiple alleles scattered throughout the autosomes
2.
Klinefelter syndrome in humans, which leads to underdeveloped testes and
sterility, is caused by which chromosomal condition?
A.
B.
C.
D.
47, XXY
47, 21+
45, X
47, XYY
3.
In birds, sex is determined by a ZW chromosome scheme, which is much like the
typical XY scheme seen in humans and many other organisms. However, in birds the
system is reversed. Males are ZZ (similar to XX in humans) and females are ZW
(similar to XY in humans). A lethal recessive allele that causes death of the embryo
occurs on the Z chromosome in pigeons. What would be the sex ratio in the offspring of
a cross between a male heterozygous for the lethal allele and a normal female?
A. 2:1 male to female
B. 3:1 male to female
C. 1:2 male to female
D. 1:1 male to female
4.
Hemophilia is caused by a sex-linked recessive gene. Assume that a man with
hemophilia marries a normal woman whose father had hemophilia. What is the
probability that their first born child has hemophilia?
A. 1/16
B. 1/8
5.
C. 1/4
D. 1/2
A Barr body is
A. a gene on the X chromosome that is responsible for female development.
B. a patch of cells that has a phenotype different from surrounding cells because
of variable X inactivation.
C. an inactivated Y chromosome, visible in the nucleus of a cell from a male
mammal.
D. none of the above.
6.
What is the expected number of Barr bodies in an individual with the karyotype
XXXYYY?
A. 0
B. 1
C. 2
D. 3
7.
The genotype “X0” produces a
A. female in Drosophila and a female in humans.
B. female in Drosophila and a male in humans.
C. male in Drosophila and a male in humans.
D. male in Drosophila and a female in humans.
8.
When an organism gains or loses one or more chromosomes but not a complete
haploid set, the condition is known as
A. polyploidy
B. aneuploidy
C. triploidy
D. trisomy
9.
When a diploid organism gains a complete haploid set of chromosomes, the
condition is known as
A. haploidy
B. aneuploidy
C. triploidy
D. trisomy
10.
A somatic cell from a human with a monosomy would contain a total of how
many chromosomes?
A. 46
B. 1
C. 45
D. 47
11.
The condition known as cri-du-chat syndrome in humans has a genetic
constitution designated as.
A. 45, X
B. 46,5pC. triploidy
D. trisomy
12.
If an organism is heterozygous for a chromosomal inversion, then
A. a condition of “semisterility” will occur in the absence of any crossing-over.
B. the organism must be phenotypically abnormal
C. chromosome number is likely altered
D. meiotic crossovers within the inverted interval will not be recovered in
offspring.
13.
Diseases associated with “genetic anticipation” are often caused by
A. insertion of foreign DNA into a chromosome.
B. expansion of trinucleotide repeats.
C. multiple inversions in the X chromosome.
D. single translocations in the X chromosome.
14.
Trisomy 21, or Down syndrome, usually occurs when there is a normal diploid
chromosomal complement of 46 chromosomes plus one (extra) chromosome #21.
Such individuals therefore have 47 chromosomes. While there is impaired fertility of
both sexes, females are more likely to be fertile than males. Assume that children are
born to a female with Down syndrome and a normal 46-chromosome male. What
proportion of the offspring would be expected to have Down syndrome?
A. One half of the offspring will be expected to have Down syndrome.
B. None of the offspring would be expected to have Down syndrome.
C. All the children would be expected to have Down syndrome.
D. Two-thirds of the offspring would be expected to have Down syndrome.
15.
While the most frequent form of Down syndrome is caused by a nondisjunction of
chromosome #21 during the formation of the mother’s egg, on rare occasion a fertilized
egg may contain a normal diploid set of chromosomes and yet the individual born
shows signs of Down syndrome. This can be explained by
A. nondisjunction in Dad’s sperm
B. a chromosomal inversion
C. a balanced translocation
D. nondisjunction in early development leading to mosaicism
16.
DNA, originally called “nuclein,” was discovered by
A. Hershey and Chase
B. Watson and Crick
C. Friedrich Miescher
D. Klug, Cummings, and Spencer
32
17.
P and 35S were used in the classic experiment conducted by Hershey and Chase
because
A. 32P labels DNA and 35S labels protein
B. 32P labels protein and 35S labels DNA
C. both radioisotopes label an entire phage including DNA and protein
D. 32P labels DNA and 35S labels RNA
18.
The basic structure of a nucleotide includes which of the following components?
A. amino acids.
B. base, sugar, phosphate.
C. phosphorous and sulfate.
D. all of the above.
19.
If 10% of the nitrogenous bases in a sample of DNA from a particular organism is
thymine, what percentage should be cytosine?
A. 15%
B. 30%
C. 40%
D. 35%
20.
Which of the following clusters of terms accurately describes DNA as it is
generally viewed to exist in prokaryotes and eukaryotes?
A. Double-stranded, parallel, (A+T)/(C+G)= variable, (A+G)/(C+T)=1.0
B. Single-stranded, antiparallel, (A+T)/(C+G)=1.0, (A+G)/C+T)=1.0
C. Double-stranded, antiparallel, (A+T)/(C+G)=variable, (A+G)/(C+T)=1.0
D. Double-stranded, antiparallel, (A+T)/C+G)=1.0, (A+G)/(C+T)=variable
21.
Which diagram shows a nucleotide with a purine base?
A.
B.
C.
D.
22.
The two strands of a DNA helix are held together (to each other) by
A. covalent bonds.
B. hydrogen bonds.
C. phosphodiester bonds.
D. glycosidic bonds.
23.
If the sequence of one strand of DNA is 5’-GCATAGGCC-3’, then the sequence
of the complementary strand is
A.
B.
C.
D.
5’-GCATAGGCC-3’
5-’CCGGATACG-3’
5’-CGTATCCGG-3’
5’-GGCCTATGC-3’
24.
Which statement is true?
A. All DNA is in the form of a right-handed double-helix all of the time.
B. DNA has the potential to form a left-handed helix in a test tube under certain
conditions.
C. Structurally, the two strands of DNA in a helix have the same polarity.
D. As a rule, a higher GC content means a lower melting point for a DNA helix.
25.
During replication of DNA, strand elongation proceeds
A. in a 5' to 3' direction on the leading strand, but in a 3' to 5' direction on the
lagging strand.
B. in a 3' to 5' direction on the leading strand, but in a 5' to 3' direction on the
lagging strand.
C. in a 5' to 3' direction on both the leading and lagging strands.
D. in a 3' to 5' direction on both the leading and lagging strands.
For questions 26-27 refer to the replication fork depicted below:
5’
3’
B
A
3’
5’
B
B
5’
3’
26.
Item A is called
A.
B.
C.
D.
27.
the leading strand.
primase.
single strand binding protein.
an Okazaki fragment.
B is most likely:
A. an RNA primer.
B. a DNA primer.
C. DNA polymerase III.
D. an exonuclease.
C
28.
The enzyme that appears to be inappropriately expressed in cancer cells and
helps to maintain the very ends of eukaryotic chromosomes is called
A. topoisomerase.
B. ligase.
C. telomerase.
D. terminase.
29.
In addition to highly repetitive and unique DNA sequences, a third category of
DNA sequences exists. What is it called and what types of elements are involved?
A.
B.
C.
D.
composite DNA, telomeres and heterochromatin
dominant DNA, euchromatin and heterochromatin
multiple gene family DNA, hemoglobin and 5.0S RNA
middle repetitive DNA, SINEs, LINEs, and VNTRs
30.
Chromatin of eukaryotes is organized into repeating interactions with protein
octomers called nucleosomes. Nucleosomes are composed of which class of
molecules?
A. histones
B. glycoproteins
C. lipids
D. nonhistone chromosomal proteins
31.
An enzyme that controls supercoiling in DNA is called a
A.
B.
C.
D.
32.
telomerase
polymerase
reverse transcriptase
topoisomerase
Mutations which arise in nature from no particular artificial agent are called
A. induced mutations.
B. spontaneous mutations.
C. chromosomal aberrations.
D. cosmic mutations.
33.
In a transition mutation,
A. a pyrimidine substitutes for a purine.
B. a purine substitutes for a purine.
C. a single nucleotide is inserted
D. a translocation occurs.
34.
A class of mutations that results in multiple contiguous amino acid changes in
proteins is likely to be which of the following?
A. base analogue.
B. transversion.
C. transition.
D. frameshift.
35. Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are
genetically incapable of repairing dimers at normal rates. Such individuals are likely to
suffer from
A. xeroderma pigmentosum.
B. phenylketonuria.
C. muscular dystrophy.
D. Huntington disease.
36.
In mammals, DNA double-strand breaks may be repaired by
A. nonhomologous end-joining.
B. base excision repair.
C. nucleotide excision repair.
D. mismatch repair.
37.
During mismatch repair in bacteria, the newly synthesized strand is distinguished
from the old strand by
A. a strand break on the old strand.
B. methylation on the new strand.
C. methylation on the old strand.
D. nothing; the strands cannot be distinguished.
38.
Virtually all transposable elements in nature
A.
B.
C.
D.
39.
can’t transpose.
have inverted terminal repeats.
encode reverse transcriptase.
transpose only in germline cells.
Which of the following is true?
A. every amino acid is coded for by a single codon.
B. there are more amino acids than there are codons.
C. every codon codes for an amino acid.
D. each codon in a gene codes for no more than one single amino acid.
40.
Which of the following represent three posttranscriptional modifications often
seen in the maturation of mRNA in eukaryotes?
A. 3'-capping, 5'-poly(A) tail addition, splicing.
B. removal of exons, insertion of introns, capping.
C. 5'-capping, 3'-poly(A) tail addition, splicing.
D. 5'-poly(A) tail addition, insertion of introns, capping.
That’s all!
ANSWER KEY
Q:
A:
1
A
2
A
3
A
4
D
5
D
6
C
7
D
8
B
9 10 11 12 13 14 15 16 17 18 19 20
C C B D B A D C A B C C
Q: 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
A: D B D B C D A C D A D B B D A A C B D C