SURNAME / INITIALS ____________________
FIRST MIDTERM TEST
Feb 9, 2008 - 9am -12 noon
25% of Final Mark
This Test paper is composed of 40 equally weighted
questions covering 16 sides (excl. cover). Please ensure
that it is complete.
Although there are no deliberate “tricks” on this paper
there is ample opportunity to make careless oversights;
READ THE QUESTIONS CAREFULLY.
1 Answers will be subject to computerized matching
analysis to detect cheating.
Since it is impossible to provide equal access to
instructors during the Test, proctors will NOT answer
questions of interpretation.
All answers must be recorded on the Scantron sheets
within the 3 hour time limit.
1 . Fill in your NAME at the top of the scantron sheet
and the exam paper
2. STUDENT NUMBER - Print the digits of your
student number in the squares provided.
Mark the corresponding bubble in the column below each
3. SECTION AND ANSWER SHEET - Leave these
4. In the EXAM CODE section enter 111
4 Mark one choice from the alternatives provided for
2 5. Wrong answers will not cancel correct answers. Part
marks may be available.
6. Submit your test paper and the Scantron sheet
1. During your summer job at Virotech, you isolate a
previously unknown virus. Analysis of its genome reveals
that it is composed of a double stranded DNA molecule
containing 14% T (thymine). Based on this information,
what would you predict the %C (cytosine) to be?
e. Cannot be determined from the information given.
2. Which of the following has the capacity to store the
3 (PLEASE NOTE: i) Twenty different amino acids can
be used to construct polypeptide chains ii) the English
alphabet has 26 letters, iii) a binary system has only 2
a. A DNA sequence composed of 36 nucleotides.
b. A polypeptide chain composed of 31 amino acids.
c. A 24 character message written using the English
d. A message of 164 characters written in binary.
e. All of the above have equal capacities to store
3. In the Hershey and Chase experiment designed to
determine the molecule of heredity, what was
radiolabeled with 35S?
4 a. protein
e. None of the choices are correct.
4. The chromosome can be considered a dynamic
organelle for the _______________ of DNA.
e. All of the choices are correct.
5. A diploid nucleus of Drosophila melanogaster contains
about 2x10 nucleotide pairs. Assume that all the
nuclear DNA is packaged into nucleosomes. How many
molecules of histone H3 would be required to package the
b. 2x10 6
d. 2x10 8
e. 1x10 8
6. In 1952, Robert Corey, and Nobel laureate Linus
Pauling proposed a triple-helix model for the structure
of DNA. This model was later shown to be incorrect.
Which of the following experimental results are not
consistent with the triple-helix model.
a. Chargaffs rule.
b. Griffith’s demonstration that mixtures of heat killed
S strains and live R strains could cause lethal
infections in mice.
6 c. Hershey and Chase’s demonstration that DNA, and
not protein, was injected into host bacterial cells
when infected by bacteriophage.
d. Both B and C are inconsistent.
e. Both A and C are inconsistent.
7. Which of the following accurately describes the results
of Avery's experiments that defined "the active principle"
(derived from heat killed S strains) that was capable of
transforming living R cells into virulent S cells.
a. the “active principle” was present in a purified
sample that contained almost nothing but DNA
b. protein digesting enzymes did not affect the ability of
the “active principle” to transform living “R” cells to
virulent “S” cells.
c. the extraction of lipids by ultracentrifugation did not
affect the ability of the “active principle” to
transform living “R” cells to virulent “S” cells.
d. DNA-digesting enzyme, DNase, destroyed the ability
of the “active principle” to transform living “R” cells
to virulent “S” cells.
e. all the above are accurate.
7 8. Which of the following molecules would be in the most
energetically favourable state to allow for the initiation of
a. a negatively supercoiled, circular dsDNA molecule
b. an overwound, linear ds DNA molecule
c. a bacterial plasmid exhibiting (+) superhelicity
d. a circular ds DNA molecule with neither (+) or (-)
e. All of the above would be in an equally favourable
9. In a certain breed of plants, dark green is determined
by the dominant allele "G" and light green is determined
by the recessive allele "g". The heterozygote shows 75%
penetrance of the dark green phenotype. In a cross of Gg
× Gg individuals what phenotypes would be expected in
400 progeny plants?
a. 250 dark green; 150 light green
b. 250 light green; 150 dark green
c. 400 dark green
d. 175 dark green; 225 light green
e. none of the above are correct
8 10. Your aunt Bertha is a judge in a civil trial where
a young man is attempting to prove that he is the
illegitimate child of a very wealthy old man who has
recently died. He wishes to be included in the distribution
of his wealth. After considering all the testimony about
how this person was conceived, the key evidence seems to
come down to one fact. The wealthy man and the mother
of the young man are both deaf but the young man is not.
Therefore the lawyer of the family argues that this proves
the wealthy man is not the father. Your aunt Bertha
comes to you for advice. What do you tell her?
9 a. The lawyer is correct, it would be impossible for the
young man to be the son of the wealthy man.
b. The lawyer is wrong, this evidence in fact proves that
the young man must indeed be the son of the wealthy
c. The lawyer is wrong, despite this evidence it would
still be possible for the young man to be the son
since the son may develop deafness later in life.
d. The lawyer is wrong, the mother and father simply
may be homozygous recessive for mutations in
different genes leading to deafness.
e. The lawyer is correct, but only if the son does not
develop deafness later in life.
11. In rats, the gene for the pigment (P) is dominant to no
pigment (p). The gene for black (B) is dominant to the
gene for cream (b). If a pigment gene (P) is absent, genes
B and b are inoperative and the rats are albino in colour.
Predict the genotypes and phenotypes of the F2 of a cross
between a black rat homozygous for the (B) and (P)
alleles, and an albino homozygous for cream. Assume
that the two genes are not linked.
a. 9 black: 7 albino
b. 13 black: 3 albino
c. 15 albino: 1 black
10 d 9 black: 3 albino: 1 cream
e. 9 black: 3 cream: 4 albino
12. During Meiosis, a number of important processes
occur; place the following events in chronological order:
i) Sister chromatids separate; ii) Chiasma visible; iii)
Ploidy number reduced; iv) Homologous chromosomes
separate; v) Independent assortment
a. i, ii, iii, iv, v
b. ii, v, iv, iii, i
c. ii, i, v, iv, iii
d. i, ii, v, iv, iii
e. v, ii, iv, iii, i
11 13. _______ -form DNA spirals to the right and is the
major form of naturally occurring DNA molecules.
12 14. You are making a physical map for the unsequenced
genome of the Poison Dart Frog. You identify three
markers (J, K and L) on chromosome 2. Given the
following data for a three point test cross, what is
the correct order of these three markers along the
JKL72 JkL 2
jkl 67 Jkl 103
JKl 557 jKl 1
13 jKL99 jkL 582
e. Two of the above are correct
14 15. Mutations in the GAL80 gene in yeast result in the
continuous expression of the GAL1, GAL7, and GAL10
genes, even in the absence of galactose. This genetic
evidence suggests that the wild-type GAL80 gene product
acts as a(n)
a. transcriptional repressor.
b. promoter element.
c. enhancer element.
d. transcriptional activator.
e. RNA polymerase.
16. You perform a testcross with a female fly who
is heterozygous for three marker genes with known
distances; white eyes (w), yellow body colour (Y) and
miniature wings (m). Calculate the degree of interference
15 in this region if you observe a double recombination event
between markers w and m 1.5% of the time.
16 17. The critical step in the regulation of most bacterial
genes occurs _____________.
a. during the initiation of transcription.
b. at release of mRNA.
c. during translation.
e. None of the choices are correct.
18. You are a researcher comparing the nonhistone and
histone chromosomal proteins of chromatin isolated from
human fibroblasts and frog fibroblast cells. Which of the
following statements would be true of the