MCB3023 Exam 3 Final Test Questions
With 100% Correct Answers 2026-2027
Elaborated.
Some anoxygenic photosynthetic bacteria are able to use _______ as an electron source.
Fe3+
CO2
Fe2+
H2O
nitrate - Answer Fe2+
Nitrogen fixation is the reduction of _______ to ammonia for cell use.
nitrite
a) dinitrogen gas
b) hydroxylamine
c) nitric oxide
b) nitrate - Answer dinitrogen gas
Cyanobacteria use _______ as an electron source for the reduction of NADP+.
carbon dioxide
glucose
nitrate
water
sulfur - Answer water
Which of these is TRUE for a chemoorganoheterotroph?
Uses organic carbon as an electron source and a carbon source.
Uses inorganic carbon as an electron source and organic carbon as a carbon source.
Uses inorganic carbon as an energy source and a carbon source.
Uses organic carbon as an electron source and inorganic carbon as a carbon source.
,Uses inorganic carbon as an energy source and organic carbon as a carbon source. - Answer
Uses organic carbon as an electron source and a carbon source.
Which of these is TRUE for a chemolithoautotroph? It uses:
organic molecules as electron sources and inorganic carbon as a carbon source.
inorganic molecules as electron sources and organic carbon as a carbon source.
inorganic molecules as energy sources and inorganic carbon as a carbon source.
organic molecules as energy sources and organic carbon as a carbon source.
inorganic molecules as energy sources and organic carbon as a carbon source. - Answer
inorganic molecules as energy sources and inorganic carbon as a carbon source.
Enzymes that break down proteins into individual amino acids are called:
reductases
dehydrogenases
proteases
lipases
amylases - Answer proteases
Which amino acids are the primary nitrogen donors for biosynthetic reactions in the cell?
glycine and glutamate
serine and glutamate
glycine and serine
glutamine and glutamate
glutamine and serine - Answer glutamine and glutamate
What is denitrification?
The reduction of nitrate to dinitrogen.
The production of nitrate from ammonia.
The reduction of dinitrogen to nitrate.
The assimilation of nitrate by the cell.
The assimilation of ammonia by the cell. - Answer The reduction of nitrate to dinitrogen.
,Nitrification is
a two-step process to oxidize nitrate into ammonium
the conversion of nitrogen gas into nitrate
a fermentation reaction
a two-step process to oxidize ammonium into nitrate - Answer a two-step process to oxidize
ammonium into nitrate
The products of the light reactions of photosynthesis are:
glucose only
glucose and ATP
ATP only
ATP and NADPH
glucose and NADPH - Answer ATP and NADPH
Lactic acid is a common fermentation product. What compound is usually reduced to form it?
acetyl-CoA
pyruvate
glucose
3-phosphoglyceraldehyde
ethanol - Answer pyruvate
Which of these is NOT an electron carrier used in the electron transport system?
cytochromes
iron-sulfur proteins
ATPase
flavoproteins
quinones - Answer ATpase
When oxygen gas reacts with hydrogen gas, water is produced as the product in this oxidation-
reduction reaction. Hydrogen donates electrons to elemental oxygen in the reaction. Which
statement below is true about this reaction?
, The electron donor in this reaction is reduced.
Hydrogen is being reduced in the reaction.
Oxygen is oxidized to water.
Oxygen is being reduced in the reaction.
The electron acceptor in this reaction is oxidized. - Answer Oxygen is being reduced in the
reaction.
What is the term for the primary pathway for fatty acid oxidation?
β-oxidation pathway
pentose phosphate pathway
Parnas pathway
reductive TCA pathway
Calvin cycle - Answer β-oxidation pathway
How would the "dark reactions" of photosynthesis best be described?
reducing power generating reactions
carbon dioxide fixing reactions
energy generating reactions
glycolytic reactions
part of photosystem II - Answer carbon dioxide fixing reactions
Methane utilization by methanotrophic methylotrophs is an environmentally important process.
Why?
The process prevents lakes from becoming anoxic.
The process prevents methane, a greenhouse gas, from entering the atmosphere.
Methane is toxic to fish.
Methane inhibits photosynthesis.
Methane is a dead-end energy source. - Answer The process prevents methane, a
greenhouse gas, from entering the atmosphere.
Soil microbes surrounding the plant root contribute to plant growth by providing the plants with
all of the following EXCEPT:
With 100% Correct Answers 2026-2027
Elaborated.
Some anoxygenic photosynthetic bacteria are able to use _______ as an electron source.
Fe3+
CO2
Fe2+
H2O
nitrate - Answer Fe2+
Nitrogen fixation is the reduction of _______ to ammonia for cell use.
nitrite
a) dinitrogen gas
b) hydroxylamine
c) nitric oxide
b) nitrate - Answer dinitrogen gas
Cyanobacteria use _______ as an electron source for the reduction of NADP+.
carbon dioxide
glucose
nitrate
water
sulfur - Answer water
Which of these is TRUE for a chemoorganoheterotroph?
Uses organic carbon as an electron source and a carbon source.
Uses inorganic carbon as an electron source and organic carbon as a carbon source.
Uses inorganic carbon as an energy source and a carbon source.
Uses organic carbon as an electron source and inorganic carbon as a carbon source.
,Uses inorganic carbon as an energy source and organic carbon as a carbon source. - Answer
Uses organic carbon as an electron source and a carbon source.
Which of these is TRUE for a chemolithoautotroph? It uses:
organic molecules as electron sources and inorganic carbon as a carbon source.
inorganic molecules as electron sources and organic carbon as a carbon source.
inorganic molecules as energy sources and inorganic carbon as a carbon source.
organic molecules as energy sources and organic carbon as a carbon source.
inorganic molecules as energy sources and organic carbon as a carbon source. - Answer
inorganic molecules as energy sources and inorganic carbon as a carbon source.
Enzymes that break down proteins into individual amino acids are called:
reductases
dehydrogenases
proteases
lipases
amylases - Answer proteases
Which amino acids are the primary nitrogen donors for biosynthetic reactions in the cell?
glycine and glutamate
serine and glutamate
glycine and serine
glutamine and glutamate
glutamine and serine - Answer glutamine and glutamate
What is denitrification?
The reduction of nitrate to dinitrogen.
The production of nitrate from ammonia.
The reduction of dinitrogen to nitrate.
The assimilation of nitrate by the cell.
The assimilation of ammonia by the cell. - Answer The reduction of nitrate to dinitrogen.
,Nitrification is
a two-step process to oxidize nitrate into ammonium
the conversion of nitrogen gas into nitrate
a fermentation reaction
a two-step process to oxidize ammonium into nitrate - Answer a two-step process to oxidize
ammonium into nitrate
The products of the light reactions of photosynthesis are:
glucose only
glucose and ATP
ATP only
ATP and NADPH
glucose and NADPH - Answer ATP and NADPH
Lactic acid is a common fermentation product. What compound is usually reduced to form it?
acetyl-CoA
pyruvate
glucose
3-phosphoglyceraldehyde
ethanol - Answer pyruvate
Which of these is NOT an electron carrier used in the electron transport system?
cytochromes
iron-sulfur proteins
ATPase
flavoproteins
quinones - Answer ATpase
When oxygen gas reacts with hydrogen gas, water is produced as the product in this oxidation-
reduction reaction. Hydrogen donates electrons to elemental oxygen in the reaction. Which
statement below is true about this reaction?
, The electron donor in this reaction is reduced.
Hydrogen is being reduced in the reaction.
Oxygen is oxidized to water.
Oxygen is being reduced in the reaction.
The electron acceptor in this reaction is oxidized. - Answer Oxygen is being reduced in the
reaction.
What is the term for the primary pathway for fatty acid oxidation?
β-oxidation pathway
pentose phosphate pathway
Parnas pathway
reductive TCA pathway
Calvin cycle - Answer β-oxidation pathway
How would the "dark reactions" of photosynthesis best be described?
reducing power generating reactions
carbon dioxide fixing reactions
energy generating reactions
glycolytic reactions
part of photosystem II - Answer carbon dioxide fixing reactions
Methane utilization by methanotrophic methylotrophs is an environmentally important process.
Why?
The process prevents lakes from becoming anoxic.
The process prevents methane, a greenhouse gas, from entering the atmosphere.
Methane is toxic to fish.
Methane inhibits photosynthesis.
Methane is a dead-end energy source. - Answer The process prevents methane, a
greenhouse gas, from entering the atmosphere.
Soil microbes surrounding the plant root contribute to plant growth by providing the plants with
all of the following EXCEPT:
