Microbial Metabolism

Which of the following compounds is NOT an enzyme?
a) cellulase
b) Beta-galactosidase
c) coenzyme A
d) sucrase
e) dehydrogenase

Coenzyme A

Which organism is NOT correctly matched to its energy source?
A) chemoautotroph-NH³
B) chemoautotroph – Fe²⁺
C) photoautotroph – CO₂
D) photoheterotroph – light
E) chemoheterotroph – glucose

Photoautotroph – CO₂

Which of the following statements about anaerobic respiration is FALSE?
A) It involves the reduction of an organic final electron acceptor.
B) The complete Kreb’s cycle is utilized.
C) It yields lower amounts of ATP when compared to aerobic respiration.
D) It generates ATP.
E) It requires cytochromes.

It involves the reduction of an organic final electron acceptor.

What is the fate of pyruvic acid in an organism that uses aerobic respiration?
A) It is reduced to lactic acid.
B) It reacts with oxaloacetate to form citrate.
C) It is converted into acetyl CoA.
D) It is catabolized in glycolysis.
E) It is oxidized in the electron transport chain.

It is converted into acetyl CoA.

Fatty acids are oxidized in
A) glycolysis.
B) the Entner-Doudoroff pathway.
C) the electron transport chain.
D) the pentose phosphate pathway.
E) the Krebs cycle.

The Krebs Cycle.

Which of the following is the best definition of oxidative phosphorylation?
A) Electrons are passed through a series of carriers to an organic compound.
B) A proton gradient allows hydrogen ions to flow back into the cells through transmembrane
protein channels, releasing energy that is used to generate ATP.
C) Electrons are passed through a series of carriers to O2.
D) ATP is directly transferred from a substrate to ADP.

A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP.

Which of the following statements about substrate-level phosphorylation is FALSE?
A) It occurs in glycolysis.
B) The oxidation of intermediate metabolic compounds releases energy that is used to generate
ATP.
C) It involves the direct transfer of a high-energy phosphate group from an intermediate metabolic compound to ADP.
D) No final electron acceptor is required.
E) It occurs in the Krebs cycle.

The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP.

Which of the following statements about photophosphorylation is FALSE?
A) Light liberates an electron from chlorophyll.
B) It requires CO₂.
C) Energy from oxidation reactions is used to generate ATP from ADP.
D) Oxidation of carrier molecules releases energy.
E) It occurs in photosynthesizing cells.

It requires CO₂.

A strictly fermentative bacterium produces energy A) only in the absence of oxygen.
B) by fermentation or aerobic respiration.
C) by aerobic respiration only.
D) by glycolysis only.
E) only in the presence of oxygen.

By glycolysis only.

The advantage of the pentose phosphate pathway is that it produces all of the following EXCEPT
A) precursors for the synthesis of amino acids.
B) NADPH.
C) precursors for nucleic acids.
D) precursors for the synthesis of glucose.
E) three ATP’s.

Three ATP’s.

Which of the following statements about beta oxidation is FALSE?
A) It is a method of catabolizing fatty acids.
B) It involves the formation of acetyl-CoA.
C) It involves the formation of 2-carbon units.
D) It is a step in glycolysis.
E) It is used in petroleum degradation.

It is a step in glycolysis.

In noncyclic photophosphorylation, O2 is released from
A) C₆H₁₂O₆
B) chlorophyll.
C) sunlight.
D) H₂O
E) CO₂.

H₂O

Which of the following is the best definition of fermentation?
A)complete catabolism of glucose to CO₂ and H₂O
B) the partial reduction of glucose to pyruvic acid
C) the partial oxidation of glucose with organic molecules serving as electron acceptors
D) the production of energy by both substrate and oxidative phosphorylation
E) production of energy by oxidative-level phosphorylation

The partial oxidation of glucose with organic molecules serving as electron acceptors.

Which of the following is NOT necessary for respiration?
A) a source of electrons
B) cytochromes
C) quinones
D) flavoproteins
E) oxygen

Oxygen.

Which one of the following would you predict is an allosteric inhibitor of the Krebs cycle enzyme,
alpha-ketoglutarate dehydrogenase?
A) NADH
B) alpha-ketoglutaric acid
C) citric acid
D) NAD+
E) ADP

NADH.

In green and purple bacteria, electrons to reduce CO₂ can come from
A) H₂O
B) chlorophyll.
C) CO₂.
D) H₂S.
E) C₆H₁₂O₆.

H₂S

Assume you are growing bacteria on a lipid medium that started at pH 7. The action of bacterial
lipases should cause the pH of the medium to
A) increase.
B) stay the same.
C) decrease.

The pH of the medium will decrease.

Which of the following uses CO₂ for carbon and H₂ for energy?
A) photoautotroph B) photoheterotroph
C) chemoheterotroph D) chemoautotroph

Chemoautotroph

Which of the following uses glucose for carbon and energy?
A) chemoheterotroph B) photoautotroph
C) photoheterotroph D) chemoautotroph

Chemoheterotroph

Which of the following has bacteriochlorophylls and uses alcohols for carbon?
A) photoautotroph B) photoheterotroph
C) chemoheterotroph D) chemoautotroph

Photoheterotroph

Cyanobacteria are a type of
A) chemoheterotroph. B) photoautotroph.
C) chemoautotroph. D) photoheterotroph.

Photoautotroph.

Which of the following statements are true?
1-Electron carriers are located at ribosomes.
2-ATP is a common intermediate between catabolic and anabolic pathways.
3-ATP is used for the long-term storage of energy and so is often found in storage granules.
4-Anaerobic organisms are capable of generating ATP via respiration.
5-ATP can be generated by the flow of protons across protein channels.

2-ATP is a common intermediate between catabolic and anabolic pathways. 4-Anaerobic organisms are capable of generating ATP via respiration. 5-ATP can be generated by the flow of protons across protein channels.

Microorganisms that catabolize sugars into ethanol and hydrogen gas would be categorized as
A) alcohol fermenters.
B) anaerobic respirers.
C) aerobic respirers.
D) homolactic fermenters.
E) heterolactic fermenters.

Heterolactic Fermenters.

Which of the following statements regarding metabolism is FALSE?
A) Anabolic reactions are degradative.
B) Heat may be released in both anabolic and catabolic reactions.
C) ATP is formed in catabolic reactions.
D) ADP is formed in anabolic reactions.

Anabolic reactions are degradative.

Which of the following statements regarding the Entner-Doudoroff pathway is TRUE?
A) It involves the pentose phosphate pathway.
B) NADH is generated.
C) ATP is generated.
D) It involves glycolysis.
E) NADH and ATP are generated.

ATP is generated.

An enzyme, citrate synthase, in the Krebs cycle is inhibited by ATP. This is an example of all of the
following EXCEPT
A) allosteric inhibition. B) feedback inhibition.
C) competitive inhibition D) noncompetitive inhibition

Competitive Inhibition

If a cell is starved for ATP, which of the following pathways would most likely be shut down?
A) glycolysis
B) Kreb’s cycle
C) pentose phosphate pathway
D) Krebs cycle and glycolysis

Pentose Phosphate Pathway

Which of the following statements regarding the glycolysis pathway is FALSE?
A) Two molecules of water are generated.
B) Two pyruvate molecules are generated.
C) Two NADH molecules are generated.
D) Four ATP molecules are generated via substrate-level phosphorylation.
E) One molecule of ATP is expended.

One molecule of ATP is expanded.

A bacterial culture grown in a glucose-peptide medium causes the pH to increase.The bacteria are
most likely
A) not growing. B) fermenting the glucose.
C) using the peptides. D) oxidizing the glucose.

Using the peptides.

Gallionella bacteria can get energy from the reaction Fe²⁺ → Fe³⁺. This reaction is an example of
A) the Calvin-Benson cycle.
B) reduction.
C) oxidation.
D) fermentation.
E) photophosphorylation.

Oxidation.

Catabolic reactions are generally degradative and hydrolytic.

True

The pentose phosphate pathway can be characterized as an anabolic pathway.

False.

In general, ATP is generated in catabolic pathways and expended in anabolic pathways.

False.

An apoenzyme that loses its coenzyme subunit will be non-functional.

True.

The use of enzymes is necessary to increase the activation energy requirements of a chemical reaction.

False.

Glycolysis is utilized by cells in both respiration and fermentation.

True.

Carbon fixation occurs during the light-independent phase of photosynthesis.

True.

Both respiration and photosynthesis require the use of an electron transport chain.

True.

Both respiration and photosynthesis use water molecules for the donation of hydrogen ions.

False.

Once an enzyme has converted substrates into products, the active site reverts back to its original
form.

True.