Microbiology Exam 3

Which form of control is the least reversible and most drastic?
A. posttranslational modification
B. alterations of DNA sequence
C. control of transcription
D. translational control

If a gene is always expressed, it is:a.constitutive
b.inducible
c.repressible
d.derepressible
e.promotable

Attenuation is a common regulatory strategy used to control the transcription of operonsthat code for
A) Carbohydrate biosynthesis
B) Amino acid biosynthesis
C) Carbohydrate degradation
D) Amino acid degradation

A quorum-sensing gene system requires the accumulation of a secreted small molecule called a(n):
A. activator
B. inducer
C. corepressor
D. autoinducer
E. repressor

The primer in DNA replication is _______ starter sequence with a free _______ group.
A) a DNA; 5' OH
B) an RNA; 5' OH
C) a DNA; 3' OH
D) an RNA; 3' OH

Which metabolic pathway produces NADPH but NOT NADH?
A) ED pathway
B) EMP pathway
C) Pentose-phosphate pathway
D) Two of the above
E) All of the above

Fermentation can be defined as
A) Partial breakdown of organic food with the use of an electron transport system.
B) Partial breakdown of organic food without the use of an electron transport system
C) Complete breakdown of organic food with the use of an electron transport system d)Complete breakdown of organic food

The term _______ refers to the heat energy absorbed or released, whereas _______ is a measure of disorder or randomness.
A) enthalpy; free energy
B) entropy; enthalpy
C) entropy; free energy
D) enthalpy; entropy

Enzymes speed up reactions by
A) Increasing the product’s kinetic energy
B) Denaturing the substrate
C) Lowering the activation energy
D) Raising the ∆G

The proton motive force drives which of the following processes in bacteria?
A) ATP biosynthesis from ADP and Pi
B) Flagellarrotation
C) Nutrient uptake
D) Two of the above
E) All of the above

Reduction potential is defined as the tendency for a molecule to:
A) Accept electrons
B) Release H+in solution
C) Release OH–in solution
D) Donate electrons

Terminal electron acceptors in anaerobic respiration include all of the following EXCEPT
A) Sulfate
B) Nitrate
C) Nitrous oxide
D) Hydrogen sulfide

The acquisition of energy by oxidation of inorganic electron donors is best defined as
A) Heterotrophy
B) Phototrophy
C) Lithotrophy
D) Auxotrophy
E) Autotrophy

Which of the following statements is NOT true regarding the electron donors in prokaryotic metabolism?
A. The use of organic compounds as electron donors is known as organotrophy.
B. Chemolithotrophyrefers to the use of inorganic molecules as electron sources.
C. Photolysis of water provides electrons to phototrophic organisms such as cyanobacteria.
D. All of the above are NOT true.
E. All of the above are true.

The laws of thermodynamics indicate that systems tend to become less ordered and that __________, a measure of disorder or randomness of the universe, always increases.
A. entropy
B. enthalpy
C. Gibbs free energy
D. all of the above
E. none of the above

In most environments, the nutrient concentrations outside the cell are lower than inside the cell. How can a microbial cell obtain nutrients if the concentration gradient is NOT favorable?
A. through active, energy-dependent transport
B. using facilitated diffusion
C. swim and tumble
D. by forming biofilms
E. none of the above

Which of the following pathways is a route for CO2fixation?
A) Calvin Cycle
B) Reductive, or reverse, TCA cycle
C) 3-hydroxypropionate cycle
D) None of the above
E) All of the above

Nitrogen fixation is found only in a few organisms and is tightly regulated because
A) Nitrogen fixation is energy-intensive.
B) Nitrogen fixation occurs only at high oxygen levels.
C) Nitrogenaseenzyme is difficult to make.
D) Fixed nitrogen is abundant, so nitrogenaseis rarely needed.

Which of the following is the reducing cofactor typicallyused in biosynthesis?
A) NADH
B) FADH2
C) NADPH
D) FAD

The level of nitrogen fixation is highest under which of the following conditions?
A) High levels of O2and high levels of NH4+
B) Low levels of O2and high levels of NH4+
C) High levels of O2and low levels of NH4+
D) Low levels of O2and low levels of NH4+

Enzymes speed up reactions by
A) Lowering the activation energy
B) Increasing the product’s kinetic energy
C) Denaturing the substrate
D) Raising the ∆G

Alkaline fermentations raise pH through the catabolism of:
A. sugars
B. nucleic acids
C. lipids
D. proteins
E. starches

Which of the following organisms is used to transport genes into plant cells?
A) Aerobacter
B) Mycobacterium
C) Agrobacterium
D) Mycoplasma

The level of nitrogen fixation is highest under which of the following conditions?
A) Low levels of O2and low levels of NH4+
B) Low levels of O2and high levels of NH4+
C) High levels of O2and low levels of NH4+
D) High levels of O2and high levels of NH4+

Production of traditionally fermented foods typically relies on _______ flora, whereas commercial fermentation generally relies on___.
A) indigenous; chemicals
B) indigenous; starter cultures
C) starter cultures; indigenous
D) normal; indigenous
E) starter cultures; normal

Which of the following organisms is a source of “single-cell protein”?
A) Salmonella
B) Spirulina
C) Rhizopus
D) Aspergillus
E) Serratia

The algal and fungal interaction within a lichen is best described as
A) Mutualism
B) Parasitism
C) Commensalism
D) Amensalism
E) Synergism

Lakes that have low concentrations of organic nutrients are said to be
A) Atrophic
B) Eutrophic
C) Prototrophic
D) Oligotrophic

Which of the following best describes methanotrophy?
A) CO2is reduced to [CH2O]
B) CO2is reduced to CH4
C) CH4is oxidized to CO2
D) CH4 is oxidized to [CH2O]

Lakes that have low concentrations of organic nutrients are said to be
A) Prototrophic
B) Eutrophic
C) Atrophic
D) Oligotrophic

Dead zones in the ocean are mainly due to a
A) High BOD that causes hyperoxia
B) Low BOD that causes hypoxia
C) Low BOD that causes hyperoxia
D) High BOD that causes hypoxia

Nitrification is the process by which
A) N2gas is converted to NH4+.
B) NH4+is oxidized to N2.
C) NH4+is oxidized to NO3–.
D) NO3–is reduced to N2O.