MBIO 3401 EXAM
MBIO 3401 | PRINCIPLES OF
MICROBIOLOGY EXAM 3
which of the following is the reducing cofactor typically used in biosynthesis?
a) NADH
b) NADPH
c) FAD
d) FADH2 - b) NADPH
Which of the following is NOT a strategy used by microbes to control the energetic costs
of biosynthesis?
a)Reductive evolution to eliminate genes for whose enzymatic products can be obtained
from other organisms through cooperation or parasitism
b)Outcompeting other organisms for scarce resources
c)Gene duplications to allow for redundancy in biosynthetic pathways
d)Tightly regulating metabolic processes to prevent production of metabolites when not
necessary - c) gene duplications to allow for redunancy in biosynthetic pathways
All of the following statements about Rubisco are true EXCEPT
a)It is found in carboxysomes in many bacteria.
b)It is one of the most prevalent proteins on Earth.
c)It consists of small (S) and large (L) subunits.
d)It catalyzes the addition of CO2 to xylulose 5 phosphate. - d) It catalyzes the addition
of CO2 to xylulose 5 phosphate.
How many turns of the Calvin cycle does it take to feed one molecule of glyceraldehyde-
3-phosphate into the biosynthesis of glucose?
MBIO 3401 EXAM
,MBIO 3401 EXAM
a)One
b)Two
c)Three
d)Six
e) None of the above - d) six
Which of the following is NOT a reason why the Calvin cycle might have evolved
requiring many different enzymes producing many different metabolic intermediates?
a)Many of the intermediates are also used as substrates for biosynthesis of other organic
compounds.
b)CO2 cannot be fixed via other mechanisms
c)The energy flow is broken down into reactions with near-zero values of ΔG.
d)The reactions are relatively easily reversible.
e)None of the above - b) CO2 cannot be fixed via other mechanisms.
Why are fatty acids suitable for modular synthesis?
a)They are synthesized in multiple different cellular locations.
b)They are constructed from repeating units.
c)Substrates for synthesis are not readily available in the cell.
d)They have multiple, varied R groups. - b) they are constructed from repeating units.
Why might organisms alter their fatty acid composition based on temperature?
a)Unsaturated fatty acids are less rigid and maintain membrane flexibility at lower
temperatures.
b)Fatty acids are more costly to synthesize at higher temperatures.
c)Fatty acids must be longer at lower temperatures to prevent membrane freezing.
MBIO 3401 EXAM
, MBIO 3401 EXAM
d)Saturated fatty acids make the membrane more permeable, allowing greater solute
diffusion at lower temperatures. - a) Unsaturated fatty acids are less rigid and maintain
membrane flexibility at lower temperatures.
Nitrogen fixation is found only in a few organisms and is tightly regulated because
a)Nitrogen fixation is energy-intensive.
b)Nitrogenase enzyme is difficult to make.
c)Fixed nitrogen is abundant, so nitrogenase is rarely needed.
d)Nitrogen fixation occurs only at high oxygen levels. - a) nitrogen fixation is energy-
intensive
The level of nitrogen fixation is highest under which of the following conditions?
a)High levels of O2 and low levels of NH4+
b)Low levels of O2 and high levels of NH4+
c)High levels of O2 and high levels of NH4+
d)Low levels of O2 and low levels of NH4+ - d) Low levels of O2 and low levels of
NH4+
Most bacteria assimilate NH4+ into which two amino acids?
a)Alanine and arginine
b)Leucine and lysine
c)Aspartate and asparagine
d)Proline and phenylalanine
Glutamate and glutamine - e) Glutamate and glutamine
Which of the following are synthesized via a branched pathway involving chorismate?
a)Fatty acids
MBIO 3401 EXAM
MBIO 3401 | PRINCIPLES OF
MICROBIOLOGY EXAM 3
which of the following is the reducing cofactor typically used in biosynthesis?
a) NADH
b) NADPH
c) FAD
d) FADH2 - b) NADPH
Which of the following is NOT a strategy used by microbes to control the energetic costs
of biosynthesis?
a)Reductive evolution to eliminate genes for whose enzymatic products can be obtained
from other organisms through cooperation or parasitism
b)Outcompeting other organisms for scarce resources
c)Gene duplications to allow for redundancy in biosynthetic pathways
d)Tightly regulating metabolic processes to prevent production of metabolites when not
necessary - c) gene duplications to allow for redunancy in biosynthetic pathways
All of the following statements about Rubisco are true EXCEPT
a)It is found in carboxysomes in many bacteria.
b)It is one of the most prevalent proteins on Earth.
c)It consists of small (S) and large (L) subunits.
d)It catalyzes the addition of CO2 to xylulose 5 phosphate. - d) It catalyzes the addition
of CO2 to xylulose 5 phosphate.
How many turns of the Calvin cycle does it take to feed one molecule of glyceraldehyde-
3-phosphate into the biosynthesis of glucose?
MBIO 3401 EXAM
,MBIO 3401 EXAM
a)One
b)Two
c)Three
d)Six
e) None of the above - d) six
Which of the following is NOT a reason why the Calvin cycle might have evolved
requiring many different enzymes producing many different metabolic intermediates?
a)Many of the intermediates are also used as substrates for biosynthesis of other organic
compounds.
b)CO2 cannot be fixed via other mechanisms
c)The energy flow is broken down into reactions with near-zero values of ΔG.
d)The reactions are relatively easily reversible.
e)None of the above - b) CO2 cannot be fixed via other mechanisms.
Why are fatty acids suitable for modular synthesis?
a)They are synthesized in multiple different cellular locations.
b)They are constructed from repeating units.
c)Substrates for synthesis are not readily available in the cell.
d)They have multiple, varied R groups. - b) they are constructed from repeating units.
Why might organisms alter their fatty acid composition based on temperature?
a)Unsaturated fatty acids are less rigid and maintain membrane flexibility at lower
temperatures.
b)Fatty acids are more costly to synthesize at higher temperatures.
c)Fatty acids must be longer at lower temperatures to prevent membrane freezing.
MBIO 3401 EXAM
, MBIO 3401 EXAM
d)Saturated fatty acids make the membrane more permeable, allowing greater solute
diffusion at lower temperatures. - a) Unsaturated fatty acids are less rigid and maintain
membrane flexibility at lower temperatures.
Nitrogen fixation is found only in a few organisms and is tightly regulated because
a)Nitrogen fixation is energy-intensive.
b)Nitrogenase enzyme is difficult to make.
c)Fixed nitrogen is abundant, so nitrogenase is rarely needed.
d)Nitrogen fixation occurs only at high oxygen levels. - a) nitrogen fixation is energy-
intensive
The level of nitrogen fixation is highest under which of the following conditions?
a)High levels of O2 and low levels of NH4+
b)Low levels of O2 and high levels of NH4+
c)High levels of O2 and high levels of NH4+
d)Low levels of O2 and low levels of NH4+ - d) Low levels of O2 and low levels of
NH4+
Most bacteria assimilate NH4+ into which two amino acids?
a)Alanine and arginine
b)Leucine and lysine
c)Aspartate and asparagine
d)Proline and phenylalanine
Glutamate and glutamine - e) Glutamate and glutamine
Which of the following are synthesized via a branched pathway involving chorismate?
a)Fatty acids
MBIO 3401 EXAM
