BIOL 230/231 Exam 2A
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the questions.
1. Which enzyme is used to synthesize complementary DNA from an mRNA template?
a) RNA polymerase
b) protease
c) reverse transcriptase
d) DNA polymerase
e) DNA gyrase
2. Inhibition of the metabolism of an alternative carbon source by glucose is called
a) induction
b) epigenetic control
c) corepression
d) catabolite repression
e) glycolysis
3. Plasmids DIFFER from transposons in that plasmids
a) become inserted into chromosome
b) are self-replicating outside of chromosome
c) move from chromosome to chromosome
d) can carry genes for antibiotic resistance
e) none of the above
4. Which of the following types of media would NOT be used to culture aerobes?
a) selective media
b) reducing media
c) enrichment media
d) differential media
e) complex media
5.
The above figure shows a typical bacterial growth curve with the y-axis indicating the log of
the number of bacteria and the x-axis indicating time in culture. In the figure, which section(s)
of the graph illustrate a logarithmic change in cell numbers?
a) a and c
b) b and d
c) a only
d) b only
e) a and b
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BIOL 230/231 Exam 2A
6. The mechanism by which lactose controls the lac operon is:
a) catabolite repression
b) DNA polymerase
c) induction
d) repression
e) translation
7. Which of the following statements is FALSE about quats?
a) cationic detergent attached to NH4+
b) most effective against gram-positive bacteria, e.g. Staphylococcus aureus
c) Pseudomonas (gram-negative bacteria) are not affected by quats
d) Organic matter does not interfere with quats activity
e) All above are true
8. Which of the following is NOT a method of horizontal gene transfer?
a) conjugation
b) binary fission
c) integration of transposon
d) transduction
e) transformation
9. Which of these disinfectants does NOT act by disrupting the plasma membrane?
a) phenolics
b) phenol
c) quats
d) halogens
e) biquanides
10. The disk-diffusion method was used to evaluate three disinfectants. See the results
in the below table:
Disinfectant
X
Y
Z
Zone of inhibition
0 mm
5 mm
10 mm
Looking at the results, what disinfectant(s) were bactericidal (not bacteriostatic!)?
a) X only
b) Y only
c) Z only
d) Y and Z
e) Can’t be determined from this method alone
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BIOL 230/231 Exam 2A
11. Mutated E.coli strain is unable to produce functional lac repressor (repressor cannot
bind the lac operator region). This strain likely
a) synthesizes lactose
b) displays inducible expression of the lac operon
c) displays constitutive expression of the lac operon
d) does not catabolize lactose
e) is unable to catabolize any sugar
12. E.coli must produce functional β-galactosidase (β-gal) enzyme to release energy
from lactose. Choose the correct binding events occurring at the lac operon:
a) Production of the regulatory gene (I) is induced, and it binds to RNA polymerase;
RNA polymerase binds to the operator and initiates transcription of β-gal.
b) RNA polymerase binds to promoter, and active repressor – bound to the operator
region - allows for transcription of structural genes, including β-gal.
c) The inducer binds the repressor - inactivating it; operator region is occupied
by no protein, RNA polymerase binds to the promoter and transcribe β-gal.
d) The repressor is activated by the inducer, and the active repressor binds to the
operator allowing the RNA polymerase to transcribe lacZ gene that is translated
to β-gal enzyme.
e) Regulatory region transcribe and translate the inducer protein, allowing for
transcription of the structural genes lacZ, Y and A (including β-gal).
13. Which of the following is most likely to be bactericidal?
a) membrane filtration
b) ionizing radiation
c) lyophilization
d) deep-freezing
e) all of the above
14. Transformation of E.coli cells requires CaCl2 treatment. How does CaCl2 achieve
a competency of the cells?
a) It allows the E. coli bacterial DNA to enter the cells by neutralizing
the repulsive negative charges of the phosphate backbone of the DNA.
b) It allows the E. coli bacterial DNA to enter the cells by neutralizing
the repulsive positive charges of the phosphate backbone of the DNA.
c) It allows the plasmid DNA to enter the cells by neutralizing
the repulsive positive charges of the phosphate backbone of the DNA
and the phospholipids of the cell membrane.
d) It keeps the transformation solution stable benefiting intact E. coli cells.
e) It allows the plasmid DNA to enter the cells by neutralizing the repulsive
negative charges of the phosphate backbone of the DNA and
the phospholipids of the cell membrane.
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BIOL 230/231 Exam 2A
15. Which of the following is the best definition of oxidative phosphorylation?
a) Electrons are passed through a series of carriers to O2
b) A proton gradient allows hydrogen ions to flow back into the cells through
transmembrane protein channels, releasing energy that is used to generate ATP
c) ATP is directly transferred from a substrate to ADP
d) Electrons are passed through a series of carriers to an organic compound
e) electrons are lost to the cytoplasm
16. You have a small gene that you want replicated by PCR. You add radioactively
labeled nucleotides to the PCR thermal cycler. After two replication cycles, you
denature the DNA. What percentage of the DNA single strands are radioactively labeled?
a) 0%
b) 25%
c) 50%
d) 75%
e) 100%
17. Which of the following uses CO2 for carbon and H2 for energy?
a) chemoautotroph
b) chemoheterotroph
c) photoautotroph
d) photoheterotroph
e) neither
18. What is the function of cAMP in the lac operon?
a) inactivates repressor
b) activates repressor
c) inactivates activator
d) activates activator
e) cAMP doesn’t play a role in the lac operon
19. Transcription begins when RNA polymerase binds to the DNA at the
a) intron
b) terminator
c) start codon
d) operator
e) promoter
20. In fermentation, ATP is generated during
a) pyruvic acid oxidation
b) pyruvic acid reduction
c) glycolysis step only
d) lactic acid oxidation
e) ethanol oxidation
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BIOL 230/231 Exam 2A
21. A prokaryotic cell hitched a ride to Earth on a space shuttle from some unknown planet.
The organism is a psychrophile, an obligate halophile, and obligate aerobe. Based on the
characteristics of the microbe, the planet is
a) cold, salty and the atmosphere has no O2
b) hot, low pH and atmosphere might or might not have O2
c) extremely high temperatures, salty and the atmosphere has no O2
d) cold, salty and the atmosphere has O2
e) hot, salty and the atmosphere has O2
22.
Referring to the above graph, which of the following is MISMATCHED?
a) c. =psychrotroph incubated at -20°C
b) b. = thermophile incubated at 100°C
c) c. = mesophile incubated at 70°C
d) all of it is mismatched
e) none of it is mismatched
23. An organism that has peroxidase and superoxide dismutase but lacks catalase is most likely an
a) aerobe
b) aerotolerant anaerobe
c) obligate anaerobe
d) autotroph
e) chemoheterotroph
24. Which of the following processes does NOT generate ATP?
a) photophosphorylation
b) the Calvin-Benson cycle
c) oxidative phosphorylation
d) substrate-level phosphorylation
e) all of the above generate ATP
25. The DNA probe, 3’-GGCTTA, will hybridize with which of the following?
a) 5’-CCGUUA
b) 5’-CCGAAT
c) 5’-GGCTTA
d) 3’-CCGAAT
e) 3’-GGCAAU
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BIOL 230/231 Exam 2A
26. Ionizing radiation causes
a) insertions and deletions
b) thymine dimers
c) nitrogenous base substitutions
d) DNA strand break
e) Ionizing radiation is not harmful
27. The chemoautotroph Acidithiobacillus can obtain energy from the oxidation
of arsenic (As3+ -> As5+). This reaction provide energy by:
a) fermentation
b) ETC
c) release of electron from chlorophyll
d) the Calvin-Benson cycle
e) glycolysis pathway
28. Which of the following pairs of terms is MISMATCHED?
a) bacteriostatic — kills vegetative bacterial cells
b) germicide — kills microbes
c) virucide — inactivates viruses
d) sterilant — destroys all living microorganisms
e) fungicide — kills yeasts and molds
29. A pastry chef accidently inoculated a cream pie with 10 Staphylococcus aureus cells.
If S. aureus has a generation time of 30 min, how many cells would be in the cream pie after 2 hrs?
a) 10
b) 16
c) 40
d) 160
e) 10,000
30. Restriction enzymes were 1st discovered with the observation that
a) DNA is restricted to the nucleus
b) phage DNA is destroyed in a host cell
c) foreign DNA is kept out of a cell
d) foreign DNA is restricted to the cytoplasm
e) all of the above
31. Which of the following is most effective for sterilizing mattresses and plastic Petri dishes?
a) chlorine
b) ethylene oxide
c) glutaraldehyde
d) autoclaving
e) nonionizing radiation
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BIOL 230/231 Exam 2A
32. The jellyfish Aequorea victoria carries the green fluorescent protein (gfp) gene that
causes the jellyfish to fluoresce under UV light. A new biotech company utilized this
GFP protein and introduced it to a special pGLO plasmid together with ampicillin-drug
resistance gene. Upon transformation of E.coli cells with pGLO, the bacterial cells will
exhibit the following:
a) no fluorescent is observed, E.coli can’t expressed genes from jellyfish
b) growth on ampicillin agar plate is observed and cells fluoresce under UV light
c) growth occur on no ampicillin (no drug) agar plate only
d) transformed E.coli cells are compromised and will never grow
e) unknown result. Not enough information given.
33. Which of the following does NOT kill endospore?
a) autoclaving
b) incineration
c) hot-air sterilization
d) pasteurization
e) all of the above kill endospores
34. Which one of the following temperatures would most likely kill a mesophile?
a) -50°C
b) 0°C
c) 9°C
d) 37°C
e) 60°C
35. Which of the following is the 4th basic step (of the steps listed below) to
genetically modify a cell?
a) transformation
b) ligation
c) plasmid cleavage
d) restriction-enzyme digestion of gene
e) isolation of gene
36. What example of mutagen is NOT correctly matched:
a) a mutation that causes insertions – frameshift mutagen
b) a mutation that causes the formation of pyrimidine dimers – nonionizing radiation
c) a mutation that is incorporated into DNA in place of a normal base – frameshift mutagen
d) a mutagen that alters adenine so that it base-pairs with cytosine – base-pair mutagen
e) all are correctly matched
37. Genetic changes in bacterial cells are due to:
a) mutation
b) recombination
c) conjugation
d) transduction or transformation
e) all above
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BIOL 230/231 Exam 2A
38. Salts and sugars work to preserve foods by creating a
a) depletion of nutrients
b) hypotonic environment
c) lower osmotic pressure
d) hypertonic environment
e) lower pH
39. Which of the following pairs is MISMATCHED?
a) ionizing radiation — hydroxyl radicals
b) ozone — takes electrons from substances
c) plasma sterilization — free radicals
d) supercritical fluids — CO2
e) ultraviolet radiation — desiccation
40. Which of the following is the best definition of the Krebs cycle?
a) the oxidation of pyruvic acid
b) the way cell produces CO2
c) a series of chemical reactions in which NADH is produced from
oxidation of pyruvic acid
d) a method of producing ATP by phosphorylating ADP
e) a series of chemical reactions in which ATP is produced from
oxidation of pyruvic acid
41. Metabolic pathways that function in BOTH anabolism and catabolism are
called ________ pathways.
a) intermediate
b) reversible
c) independent
d) redox
e) amphibolic
42. Which of the following enzymes joins DNA strands, joins Okazaki fragments, and
mends gaps in the DNA backbone during excision repair?
a) RNA polymerase
b) DNA polymerase
c) DNA ligase
d) DNA gyrase
e) Methylase
43. Cyclic and noncyclic photophosphorylation differ in the following:
a) chlorophyll receives electrons from hydrogen atoms
b) ATP is produced
c) occurs in photosynthetic cells only
d) light dependent reaction
e) there is no difference
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BIOL 230/231 Exam 2A
44. pUC19 is a plasmid vector containing ampR, ori, and lacZ gene with a multiple cloning
site containing HindIII within the lacZ gene. This vector was use to create a recombinant
plasmid by inserting a gene of interest into the HindIII restriction site within lacZ gene.
The bacteria transformed with the recombinant plasmid and plated on media containing
ampicillin and X-gal will
a) form blue, ampicillin-resistant colonies.
b) form blue, ampicillin-sensitive colonies.
c) form white, ampicillin-resistant colonies.
d) form white, ampicillin-sensitive colonies.
e) not grow.
45. In anaerobic respiration, the final electron acceptor is
a) oxygen
b) ATP
c) an inorganic molecule other than oxygen
d) an organic molecule
e) does not exist
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