MIC 205A EXAM 2 QUESTIONS WITH VERIFIED SOLUTIONS LATEST
UPDATE 2026
Although the actual procedure is much more involved, the basic metabolism of wine-
making involves inoculating grape juice with a special strain of the yeast
Saccharomyces cerevisiae. S. cerevisiae will preferentially perform aerobic
respiration on sugars in the juice but can also ferment those sugars to yield CO2 and
alcohol, an important component of wine. Assume you inoculate a completely full
container of juice and then close the lid. What will the yeast do? - Answers They will
grow aerobically, consume the O2 dissolved in juice, and then switch to fermenting
sugars yield alcohol
Which of the following are examples of biofilms? - Answers
You inoculate a flask containing a complex medium with a culture of bacteria and use
a spectrophotometer to measure the absorbance of the culture to detect growth. Initial
measurements show a modest turbidity (cloudiness) that remains unchanged for the
first few hours, followed by a steady increase for the rest of the day. Why was there
this delay in growth following inoculation? - Answers
You are setting up an enrichment culture to look for methylotrophic bacteria in a
sample of water from Lake Washington in Seattle. Methylotrophs are capable of
obtaining their carbon and energy needs from single carbon compounds such as
methanol. In your enrichment culture, you provide methanol and a variety of macro-
and micro-nutrients to encourage growth. However, which of the following must you
leave out if you are to successfully enrich for methylotrophs? - Answers Any other
carbon source
You leave several tomatoes in your refrigerator when you go on vacation. When you
get home, the tomatoes are covered in microbial growth. Select ALL the
characteristics you can assign to these microbes. - Answers Fastidious
Following the Exxon Valdez oil spill, beaches in Prince William Sound were treated
with nitrogen compounds in order to enhance the bioremediation of the oil. What does
this tell you about the ecosystem of these beaches? - Answers When the arrival of
large quantities of hydrocarbon, nitrogen was a limiting for microbial growth
Some enzymes require a cofactor or a coenzyme in order to be active. What is the
difference between cofactors and coenzymes? - Answers Cofactors are non-protein
components that assist enzymes and are typically trace elements; coenzymes are
organic cofactors that loosely carry molecules or electrons
Streptococcus pneumoniae lacks an electron transport chain. Therefore, S.
pneumoniae generates ATP via ______. - Answers Fermentation
Consider how an aerobically respiring bacterial cell uses glycolysis, the TCA cycle,
and oxidative phosphorylation to break apart and oxidize glucose. What are the three
main benefits these central metabolic pathways yield to the cell? - Answers ATP,
reduced electron carriers, and precursor metabolites
You are studying the metabolism of the phototrophic green sulfur bacterium
Chlorobaculum tepidum and realize that it is running a reversed TCA cycle! How do
you explain this observation? - Answers C. tepidum is using the reversed TCA cycle
to fix CO2
Removing the electron transport chain of E. coli would - Answers Prevent oxidative
phosphorylation
Scientists isolated a new species of bacteria growing in sediments collected from a 63
meter deep site at the bottom of Lake Washington in Seattle This species, named
, Labrys methylaminiphilus, is capable of obtaining its carbon and energy needs from
methylamine (CH3NH2), a derivative of ammonia (NH3) in which one H atom is
replaced by a methyl (CH3) group. L. methylaminiphilus grows at a temperature
range of 10-35°C, with optimal growth at 28-30°C, and a pH range of 4.0-9.5, with
optimal growth at 5.0-7.0. Because methylamine is a single carbon compound
resulting from the breakdown of decaying organic matter, methylotrophic ("methyl-
feeding") bacteria like L. methylaminiphilus play an important role in carbon cycling
in lake sediments and other environments.
Consider the growth of L. methylaminiphilus on methylamine. How would you
classify this species based on its metabolism? - Answers chemoorganoheterotroph
Anabaena is a genus of filamentous cyanobacteria commonly found in aquatic
environments, where it harvests energy from sunlight and fixes both carbon dioxide
and nitrogen. Knowing this, how would you classify Anabaena? - Answers
Photoautotroph
Greenlake is a small lake in Seattle, WA that sometimes experiences blooms of
cyanobacteria, photosynthetic nitrogen-fixing bacteria that typically grow as
filaments. These blooms are especially likely to occur during warm summer weather
and result in the production of large quantities of biomass that then dies off and
decomposes, leading to unpleasant odors. In addition to the aesthetic problems, some
strains make toxins that can be dangerous to ingest, leading to the closing of the lake.
Treatment of the water with alum (aluminum sulfate) to remove phosphorus from the
water has helped to limit growth of cyanobacteria.
How would you classify the cyanobacteria from Greenlake in terms of their carbon
and energy sources? - Answers Photoautotroph
Which of the following statements regarding bacterial gene control is FALSE? -
Answers Genes for constitutive enzymes can be turned off and on as necessary
DNA in cells can encode for thousands of different proteins. Why do cells require
mechanisms to regulate expression of the genes that code for these proteins? -
Answers Not all proteins are needed at all times, or in equal amounts. Regulating their
expression saves time and energy.
Transcription is often controlled by DNA-binding proteins. A(n) ______ is a
regulatory protein that blocks transcription, while a(n) ______ is a regulatory protein
that facilitates transcription. - Answers repressor; activator
If a 75 base-pair fragment of DNA has 25 cytosines in it, how many adenines would
you expect it to have? - Answers 50
Which of the following statements regarding transcription and translation is TRUE? -
Answers Eukaryotes must splice out introns following transcriptions, while
prokaryotes DO NOT.
RNA interference (RNAi) is a mechanism by which - Answers Eukaryotic cells
destroy RNA transcripts in a selective and specific manner ton control gene
expression
Which regions of the gene (or segment of DNA) shown here encodes the amino acid
sequence of a protein? - Answers A,C,E
- They encode only exons while introns are spliced out
Antigenic variation is a phenomenon used by some bacteria (such as Neisseria
gonorrhoeae) to evade host immune mechanisms. In this process, the cells - Answers
Can change the characteristics of certain surface protein on bacteria, forcing immune
response to constantly adapt.
UPDATE 2026
Although the actual procedure is much more involved, the basic metabolism of wine-
making involves inoculating grape juice with a special strain of the yeast
Saccharomyces cerevisiae. S. cerevisiae will preferentially perform aerobic
respiration on sugars in the juice but can also ferment those sugars to yield CO2 and
alcohol, an important component of wine. Assume you inoculate a completely full
container of juice and then close the lid. What will the yeast do? - Answers They will
grow aerobically, consume the O2 dissolved in juice, and then switch to fermenting
sugars yield alcohol
Which of the following are examples of biofilms? - Answers
You inoculate a flask containing a complex medium with a culture of bacteria and use
a spectrophotometer to measure the absorbance of the culture to detect growth. Initial
measurements show a modest turbidity (cloudiness) that remains unchanged for the
first few hours, followed by a steady increase for the rest of the day. Why was there
this delay in growth following inoculation? - Answers
You are setting up an enrichment culture to look for methylotrophic bacteria in a
sample of water from Lake Washington in Seattle. Methylotrophs are capable of
obtaining their carbon and energy needs from single carbon compounds such as
methanol. In your enrichment culture, you provide methanol and a variety of macro-
and micro-nutrients to encourage growth. However, which of the following must you
leave out if you are to successfully enrich for methylotrophs? - Answers Any other
carbon source
You leave several tomatoes in your refrigerator when you go on vacation. When you
get home, the tomatoes are covered in microbial growth. Select ALL the
characteristics you can assign to these microbes. - Answers Fastidious
Following the Exxon Valdez oil spill, beaches in Prince William Sound were treated
with nitrogen compounds in order to enhance the bioremediation of the oil. What does
this tell you about the ecosystem of these beaches? - Answers When the arrival of
large quantities of hydrocarbon, nitrogen was a limiting for microbial growth
Some enzymes require a cofactor or a coenzyme in order to be active. What is the
difference between cofactors and coenzymes? - Answers Cofactors are non-protein
components that assist enzymes and are typically trace elements; coenzymes are
organic cofactors that loosely carry molecules or electrons
Streptococcus pneumoniae lacks an electron transport chain. Therefore, S.
pneumoniae generates ATP via ______. - Answers Fermentation
Consider how an aerobically respiring bacterial cell uses glycolysis, the TCA cycle,
and oxidative phosphorylation to break apart and oxidize glucose. What are the three
main benefits these central metabolic pathways yield to the cell? - Answers ATP,
reduced electron carriers, and precursor metabolites
You are studying the metabolism of the phototrophic green sulfur bacterium
Chlorobaculum tepidum and realize that it is running a reversed TCA cycle! How do
you explain this observation? - Answers C. tepidum is using the reversed TCA cycle
to fix CO2
Removing the electron transport chain of E. coli would - Answers Prevent oxidative
phosphorylation
Scientists isolated a new species of bacteria growing in sediments collected from a 63
meter deep site at the bottom of Lake Washington in Seattle This species, named
, Labrys methylaminiphilus, is capable of obtaining its carbon and energy needs from
methylamine (CH3NH2), a derivative of ammonia (NH3) in which one H atom is
replaced by a methyl (CH3) group. L. methylaminiphilus grows at a temperature
range of 10-35°C, with optimal growth at 28-30°C, and a pH range of 4.0-9.5, with
optimal growth at 5.0-7.0. Because methylamine is a single carbon compound
resulting from the breakdown of decaying organic matter, methylotrophic ("methyl-
feeding") bacteria like L. methylaminiphilus play an important role in carbon cycling
in lake sediments and other environments.
Consider the growth of L. methylaminiphilus on methylamine. How would you
classify this species based on its metabolism? - Answers chemoorganoheterotroph
Anabaena is a genus of filamentous cyanobacteria commonly found in aquatic
environments, where it harvests energy from sunlight and fixes both carbon dioxide
and nitrogen. Knowing this, how would you classify Anabaena? - Answers
Photoautotroph
Greenlake is a small lake in Seattle, WA that sometimes experiences blooms of
cyanobacteria, photosynthetic nitrogen-fixing bacteria that typically grow as
filaments. These blooms are especially likely to occur during warm summer weather
and result in the production of large quantities of biomass that then dies off and
decomposes, leading to unpleasant odors. In addition to the aesthetic problems, some
strains make toxins that can be dangerous to ingest, leading to the closing of the lake.
Treatment of the water with alum (aluminum sulfate) to remove phosphorus from the
water has helped to limit growth of cyanobacteria.
How would you classify the cyanobacteria from Greenlake in terms of their carbon
and energy sources? - Answers Photoautotroph
Which of the following statements regarding bacterial gene control is FALSE? -
Answers Genes for constitutive enzymes can be turned off and on as necessary
DNA in cells can encode for thousands of different proteins. Why do cells require
mechanisms to regulate expression of the genes that code for these proteins? -
Answers Not all proteins are needed at all times, or in equal amounts. Regulating their
expression saves time and energy.
Transcription is often controlled by DNA-binding proteins. A(n) ______ is a
regulatory protein that blocks transcription, while a(n) ______ is a regulatory protein
that facilitates transcription. - Answers repressor; activator
If a 75 base-pair fragment of DNA has 25 cytosines in it, how many adenines would
you expect it to have? - Answers 50
Which of the following statements regarding transcription and translation is TRUE? -
Answers Eukaryotes must splice out introns following transcriptions, while
prokaryotes DO NOT.
RNA interference (RNAi) is a mechanism by which - Answers Eukaryotic cells
destroy RNA transcripts in a selective and specific manner ton control gene
expression
Which regions of the gene (or segment of DNA) shown here encodes the amino acid
sequence of a protein? - Answers A,C,E
- They encode only exons while introns are spliced out
Antigenic variation is a phenomenon used by some bacteria (such as Neisseria
gonorrhoeae) to evade host immune mechanisms. In this process, the cells - Answers
Can change the characteristics of certain surface protein on bacteria, forcing immune
response to constantly adapt.
