Microbio Final Exam Sample 18

Examples of multiple choice questions
1/__E__ If an organism is inefficient at generating ATP, it probably (1 point)
A. possesses a Krebs cycle
B. grows rapidly
C. uses a variety of mechanisms to generate ATP
D. maintains huge reserves of ATP
E. does not use aerobic respiration
2/_D___ Which of the following is not an end product of fermentation? (1 point)
A. lactic acid
B. acetic acid
C. propionic acid
D. pyruvic acid
E. ethanol
3/__B__ Which of the following is the best definition of fermentation? (1 point)
A. The production of ethanol from glucose
B. The oxidation of a carbohydrate with organic molecules serving as final electron acceptors
C. The reduction of glucose to pyruvate
D. The complete catabolism of glucose to CO2 and H2O
E. The production of ATP from glucose
4/___A__ Carotenoids function in which part of the photosynthetic apparatus? (1 point)
A. Light harvesting center (antenna)
B. Reaction center
C. Electron transport chain
D. None of the above
5/__D___ The most metabolically versatile of the photosynthetic bacteria is (1 point)
A. green sulfur
B. purple sulfur
C. purple nonsulfur
D. cyanobacteria
6/__D___ A merozygote: (2 points)
A. is a bacterial cell which is diploid for a small part of its information
B. arises from conjugation involving an F’ (F prime) recipient.
C. can be used to demonstrate the complementation of some bacterial genes.
D. a and c.
7/__D__ Which of the following is NOT a requirement for culturing bacteria on culture media? (1
A. Knowing the oxygen requirements
B. Knowing the nutrient requirements
C. Knowing the pH requirements
D. Knowing the UV requirements
8/__B__During which phase of the growth curve is cellular reproduction most active? (1 point)
A. Lag Phase
B. Log Phase
C. Stationary Phase
D. Death Phase
9/__C__When an Hfr cell conjugates with an F- cell, what is the result? (1 point)
F+ cell
F' cell
F- cell
Hfr cell
Examples of short problems and questions.
(1) Anoxygenic photophosphorylation is also called cyclic photophosphorylation. Since the
electrons can be recycled, why do these organisms need an electron donor? (2 points)
To produce reduced co-factors for biosynthesis
(2). Pseudomonas aeruginosa is an obligate aerobe. Student Emil grows P. aeruginosa cells in
saline buffer at low pH, and does not add glucose and any other energy source. To his bewilderment,
he observes that cells are still capable of producing a little ATP. Provide an explanation for Emil’s
observation (3 points).
At low pH, the concentration of H+ outside the cell is high resulting transiently in a favorable pH
gradient to fuel ATP synthase and produce some ATP.
(3). Student Emil isolates a new antibiotic X from a soil bacterium and discovers that its
hydrophobic nature allows it to dissolve in the membrane and shuttle protons from the outside of the
cell to the inside.
(3-A). What are all the potential effects or targets of antibiotic X on a bacterial cell sensitive to X?
(3 points)
Antibiotic X may inhibit:
ATP generated by oxidative phosphorylation
motility by flagellar rotation
ability to use proton gradient for transport of subtanses into or outside of cell
(3-B). Will antibiotic X affect electron transport? (1 point)
electron transport will not be affected.
(4). What would be the phenotype of a strain of E. coli unable to produce HPr (Histine rich protein)?
(2 points).
This strain should be unable to transport carbohydrates via the PEP-PTS system
(5). Student Emil isolates a variant of Streptococus pneumonia that no longer forms smooth colonies
instead it forms rough colonies on plate. What would be the easiest way to restore the “smooth”
phenotype? (3 points)
Emil should take advantage of the natural competence of this organism. DNA can be extracted from
bacteria that form smooth colony and mixed with “rough colony” bacteria. DNA will be taken up by
the rough colony bacteria and recombined. New strains should be screened for appearance of the
smooth colony phenotype on plate.
(6). Student Emil wishes to identify genes required for chromosome partitioning in E. coli.
What type of mutagenesis can he use?
Mutagenesis approach that isolates conditional lethal and do replica plating
Mutation approach using transposon assuming a no- essential gene is involved
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