Deck 8: Microbial Metabolism

Question 1

Catabolic reactions

A) are endergonic.
B) are hydrolytic and involve breaking down larger molecules into smaller molecules.
C) are hydrolytic.
D) involve breaking down larger molecules into smaller molecules.
E) are endergonic and are hydrolytic.

Answer 1

are hydrolytic and involve breaking down larger molecules into smaller molecules.

Question 2

In the typical ATP- ADP cycle, which part of the ATP molecule is removed when energy is released and added back when energy is stored?

A) the terminal two phosphate groups
B) adenine
C) the terminal phosphate group
D) ribose
E) all three phosphate groups

Answer 2

the terminal phosphate group

Question 3

What is the relationship between the ATP- ADP cycle and catabolic and anabolic reactions?

A) Energy released from catabolic reactions is used to break ATP down to ADP. Then the energy needed for anabolic reactions is released by to recharging ADP back to ATP.
B) Energy released from anabolic reactions is used to recharge ADP back to ATP. Then the energy needed for catabolic reactions is released by breaking ATP down to ADP.
C) Catabolic reactions require energy, which is provided by anabolic reactions. ADP is recharged to ATP by energy from anabolic reactions.
D) Energy released from catabolic reactions is used to recharge ADP back to ATP. Then the energy needed for anabolic reactions is released by breaking ATP down to ADP.
E) There is no relationship between the ATP- ADP cycle and catabolic and anabolic reactions.

Answer 3

Energy released from catabolic reactions is used to recharge ADP back to ATP. Then the energy needed for anabolic reactions is released by breaking ATP down to ADP.

Question 4

Refer to the numbered steps in the figure when answering the question. Which step shows an energy investment in the form of ATP?

A) steps 1 and 3
B) steps 1 and 10
C) steps 3 and 7
D) steps 7 and 10
E) steps 1, 3, 7, and 10

Question 5

When electrons are removed from nutrients via an oxidation reaction, the coupled reduction reaction may be

A) NADH - NAD+.
B) NAD+ - NADH.
C) FAD - FADH₂.
D) either FAD - FADH₂ or NAD+ - NADH.
E) either NAD+ - NADH or NADH - NAD+.

Question 6

The term includes both the chemical reactions that organisms use to break down substances to release energy, as well as the reactions that use released energy to build new substances.

A) oxidation- reduction
B) metabolism
C) catabolism
D) biosynthesis
E) anabolism

Question 7

The figure shows which process?

A) allosteric inhibition
B) competitive inhibition
C) either allosteric inhibition, competitive inhibition, or non- competitive inhibition
D) allosteric activation
E) non- competitive inhibition

Question 8

Ribozymes are enzymes which

A) are made of RNA.
B) may have medical applications as antiviral therapies.
C) work on RNA substrates.
D) are made of RNA and work on RNA substrates.
E) are made of RNA, work on RNA, and may have medical applications as antiviral therapies.

Question 9

Which coenzyme is incorrectly matched with its function?

A) Coenzyme A: Metabolism of pyruvic acid and lipids
B) THF / DHF: Make purines and pyrimidines
C) Cobalamin: Transfer of CO₂ groups
D) FAD / FMN: Electron transfers
E) NAD+ /NADP+: Electron transfers

Question 10

Which of the following factors may influence an enzyme's activity by altering its three- dimensional structure?

A) temperature
B) pH
C) pH and temperature only
D) competitive inhibitor
E) pH, temperature, and competitive inhibitor

Question 11

Catabolic and anabolic reactions depend upon each other, as evidenced by which of the following statements?

A) Catabolic reactions release energy which is used by anabolic reactions
B) Anabolic reactions split bigger molecules into smaller components, which are in turn used by catabolic reactions to build more complex molecules.
C) Catabolic reactions split bigger molecules into smaller components which are used by anabolic reactions to build more complex molecules AND catabolic reactions release energy which is used by anabolic reactions.
D) Anabolic reactions split bigger molecules into smaller components, which are in turn used by catabolic reactions to build more complex molecules AND catabolic reactions release energy which is used by anabolic reactions.
E) Catabolic reactions split bigger molecules into smaller components which are used by anabolic reactions to build more complex molecules.

Question 12

The graph shows enzyme activity as a function of temperature for a mesophilic microbe. How would you predict that the graph would change if the organism was a psychrophile (an organism that thrives at low temperatures)?

A) The graph would be similar, but would be shifted toward the right.
B) The graph would be a horizontal straight line.
C) The graph would be similar, but would be shifted toward the left.
D) The graph would not peak then drop off, but would continue rising indefinitely.
E) The graph would be wider (extended further both left and right) but the peak would be lower.

Question 13

Oxidation of nutrients by cells results in

A) a requirement for energy which can be used to recharge ADP to ATP.
B) a release of energy, which is released by converting ATP to ADP.
C) a release of energy, which can be used to recharge ADP to ATP.
D) a requirement of energy which can be obtained by converting ATP to ADP.
E) either a release or a requirement for energy depending on what type of nutrient is available.

Question 14

Which structural and functional feature(s) listed are key to an enzyme's activity?

A) contains an active site where the enzyme can interact with a specific substrate
B) consumed each time a reaction takes place
C) consumed each time a reaction takes place and contains an active site where the enzyme can interact with a specific substrate
D) consumed each time a reaction takes place and consists of a three- dimensional protein structure that interacts with a substrate in a fixed "lock- and- key" model
E) consists of a three- dimensional protein structure that interacts with a substrate in a fixed "lock- and- key" model

Question 15

Enzymes are necessary for cells because

A) enzymes slow down chemical reactions that would otherwise occur too quickly to facilitate life.
B) enzymes allow chemical reactions to occur under physiological conditions and within a time frame conducive to life.
C) enzymes allow chemical reactions to occur under physiological conditions.
D) enzymes allow chemical reactions to take place that would otherwise be impossible.
E) enzymes allow chemical reactions to occur quickly enough to facilitate life.

Question 16

Anabolic reactions

A) are endergonic.
B) involve dehydration synthesis.
C) are endergonic and involve breaking down larger molecules into smaller molecules.
D) are endergonic and involve dehydration synthesis.
E) involve breaking down larger molecules into smaller molecules.

Question 17

Which of the following does not describe cellular respiration?

A) involves a transfer of energy into the bonds of ATP
B) occurs in part in the mitochondria of eukaryotic cells
C) may include multiple pathways including glycolysis, an intermediate step, the Krebs cycle and fermentation
D) collection of reactions that extract energy from food using redox reactions
E) may occur in both prokaryotic and eukaryotic cells

Question 18

Which phosphorylation mechanism for recharging ADP to ATP is incorrectly matched with its description?

A) Photophosphorylation: Passes electrons energized by solar energy through an electron transport chain
B) Substrate- level phosphorylation: A phosphate is transferred to ADP from a high- energy substrate after passing through an electron transport chain.
C) Oxidative Phosphorylation: Passes electrons stripped from nutrients through an electron transport chain
D) The descriptions for oxidative phosphorylation and photophosphorylation are incorrectly matched.
E) The descriptions for oxidative phosphorylation, photophosphorylation, and substrate- level phosphorylation are incorrectly matched.

Question 19

Which facts about enzymes are not visualized in this figure?

A) Enzymes stabilize the transition state of the reaction-that point where the reactants are becoming the products.
B) A cofactor is often required for enzyme activity.
C) Enzymes are not consumed or permanently changed in a reaction.
D) A substrate binds to an enzyme at the active site as described by the "induced- fit" model
E) Specific products are generated.

Question 20

Enzymes can lower the activation energy of a chemical reaction by

A) raising the temperature so that reactants collide more forcefully.
B) properly positioning reactants and stabilizing the transition state.
C) properly positioning reactants and raising the temperature so that reactants collide more forcefully.
D) stabilizing the transition state.
E) properly positioning reactants.

Question 21

Which of the following statements correctly describes what happens during chemiosmosis?

A) Protons are added directly to ADP to recharge it to ATP.
B) Protons flow through the ATP synthase enzyme from the side of the membrane where they are lower in concentration to the side where they are higher in concentration.
C) The purpose is to generate water from oxygen.
D) Only electrons from the reduced carrier NADH are deliver to the electron transport chain; the reduce carrier FADH₂ takes its electrons elsewhere.
E) The energy of protons flowing through the ATP synthase enzyme powers the recharge of ADP to ATP.

Question 22

In order to harvest energy from polysaccharides, lipids or proteins, cells must use to break down these large macromolecules extracellularly before bringing them into the cell.

A) glycogenesis
B) deamination
C) beta- oxidation
D) exoenzymes
E) Entner- Doudoroff pathway

Question 23

One of the ways that cells balance anabolism and catabolism is to

A) use separate coenzymes such as NAD+ vs. NADP+ for catabolic vs. anabolic pathways.
B) use the same enzyme to run a reaction in both the catabolic and anabolic direction and use feedback inhibition to shut down a pathway that is not needed.
C) use feedback inhibition to shut down a pathway that is not needed and use separate coenzymes such as NAD+ vs. NADP+ for catabolic vs. anabolic pathways.
D) use feedback inhibition to shut down a pathway that is not needed.
E) use the same enzyme to run a reaction in both the catabolic and anabolic direction.

Question 24

Gluconeogenesis

A) can be accomplished by funneling intermediates from glycolysis, the Krebs cycle, and lipid or protein catabolism.
B) is an example of biosynthesis.
C) is building glucose from non- sugar starting materials and can be accomplished by funneling intermediates from glycolysis, the Krebs cycle, and lipid or protein catabolism.
D) is building glucose from non- sugar starting materials and can be accomplished by funneling intermediates from glycolysis, the Krebs cycle, and lipid or protein catabolism and an example of biosynthesis.
E) is building glucose from non- sugar starting materials.

Question 25

Which molecule is the product of the intermediate step which is a direct input into the Krebs cycle?

A) carbon dioxide
B) ATP
C) pyruvic acid
D) NADH
E) acetyl CoA

Question 26

The intermediate(s) needed to synthesize lipids from sugar catabolism is (are)

A) acetyl CoA.
B) citric acid and dihydroxyacetone phosphate (DHAP).
C) citric acid.
D) dihydroxyacetone phosphate (DHAP).
E) acetyl CoA and dihydroxyacetone phosphate (DHAP).

Question 27

The main goal of fermentation is to sustain ATP production by glycolysis. This is accomplished by

A) passing the electrons on NADH to pyruvic acid, regenerating NAD+ so glycolysis can continue.
B) enables the cell to use its respiratory chain without oxygen being available.
C) producing acids and alcohols which the microorganism can use as an alternative nutrient source when glucose is not available.
D) producing acids which lower cellular pH to promote more efficient ATP recharge.
E) diverting glycolysis intermediates into the pentose phosphate pathway.

Question 28

Refer to the numbered steps in the figure when answering the question. Two carbons in the form of acetyl- CoA enter the Krebs cycle by joining with oxaloacetic acid, a 4- carbon molecule. During which step does carbon leave the Krebs cycle in the form of CO₂?

A) step 1
B) step 3
C) step 4
D) step 1 and step 3 and step 4
E) step 3 and step 4

Question 29

Refer to the numbered steps in the figure when answering the question. Which step is a redox reaction?

A) step 1
B) step 3
C) step 4
D) step 6
E) step 9

Question 30

Which is not one of the categories used to classify an organism based on its nutrition?

A) source of energy for making ATP and ability to run either catabolic or anabolic pathways
B) source of energy for making ATP
C) ability to fix carbon
D) initial source of electrons for reduction reactions
E) ability to run either catabolic or anabolic pathways

Question 31

Sequence the following events as they occur at the electron transport chain. I. Protons accumulate on one side of the membrane to form a proton motive force.
II) The coenzymes NADH and FADH₂ drop off electrons to the carriers in the respiratory chain.
III) Protons flow through ATP synthase which captures the energy of the flowing protons and uses it to recharge ATP.
IV) Electrons moving through the chain release energy to pump proteins across the membrane where the carrier proteins are found.

A) I - III - IV - II
B) I - II - III - IV
C) III - II - IV - I
D) II - IV - I - III
E) II - I - IV - III

Question 32

Which of the following pathways are operational in a cell growing via fermentation?

A) Krebs cycle
B) glycolysis, intermediate step, and the Krebs cycle
C) glycolysis
D) intermediate step
E) glycolysis and intermediate step only

Question 33

Many strains of E. coli are able to grow on minimal media which consists only of a single sugar, usually glucose, and inorganic salts to provide nitrogen, sulfur, phosphorous and trace nutrients. What does this tell you about E. coli's biosynthetic capabilities?

A) E. coli can funnel intermediates from glycolysis, the intermediate step, and the Krebs cycle to synthesize amino acids, fatty acids, glycerol, and nucleotides.
B) E. coli will be unable to build the peptidoglycan it needs for its cell wall.
C) All amino acids are "essential" to E. coli.
D) E. coli will be unable to perform amination.
E) E. coli will use salvage pathways to make nucleotides.

Question 34

Which is the key difference between aerobic and anaerobic respiratory chains?

A) Aerobic respiratory chains that accept electrons depend on membrane- associated electron carrier molecules that carry out redox reactions while anaerobic chains use cytoplasm- associated molecules that carry out redox reactions.
B) Aerobic respiratory chains always use oxygen as the final electron acceptor while anaerobic respiratory chains may use a variety of inorganic substances other than oxygen as the final electron acceptor.
C) Aerobic respiratory chains are organized so that electrons are passing from a higher to lower energy state while anaerobic chains are organized so that electrons are passing from a lower to a higher energy state.
D) Aerobic respiratory chains accept electrons from both NADH and FADH₂ while anaerobic chains only accept electrons from FADH₂.
E) Aerobic respiratory chains are found in prokaryotic cells only while anaerobic chains are found in eukaryotic cells only.

Question 35

Which statement is not true about the pentose phosphate pathway?

A) It converts 5- carbon sugars into 3- and 6- carbon for use in glycolysis.
B) It can be used in part by photosynthetic cells to build glucose from carbon dioxide.
C) It allows cellular respiration to occur without the need for oxygen.
D) It diverts glucose- 6- phosphate from glycolysis to synthesize 5- carbon sugars needed for nucleotides.
E) It produces the coenzyme NADPH needed for anabolic pathways.

Question 36

Cyanide is a poison which prevents the last carrier in the electron transport chain (cytochrome C oxidase) from transferring the electron to the final electron acceptor. Which of the following would not be a consequence of exposure to this poison?

A) Movement of electrons through the chain would stop.
B) Protons would no longer be pumped outside the membrane.
C) ADP would no longer be recharged to form ATP.
D) Carbon dioxide would continue to be generated.
E) Glycolysis, the intermediate reaction, and the Krebs cycle would stop as the cell would run out of the necessary oxidized coenzymes NAD+ and FAD.

Question 37

A pathway that functions simultaneously in both anabolism and catabolism is termed

A) cyclic.
B) allosteric.
C) amphibolic.
D) biosynthetic.
E) redox.

Question 38

Consider this summarized chemical reaction for aerobic cellular respiration: C6H12O6 + 6 O₂ + 38 ADP + 38 PO32- - 6 CO₂ + 6 H₂O + 38 ATP What would be different in a summarized chemical reaction for anaerobic cellular respiration?

A) The oxygen would be replaced by a different inorganic compound.
B) The numbers of ADP, PO32- , and ATP used / generated would be different.
C) The water would be replaced by a different reduced product.
D) The numbers of ADP, PO32- , and ATP used / generated would be different and the oxygen would be replaced by a different inorganic compound and the water would be replaced by a different reduced product.
E) The oxygen would be replaced by a different inorganic compound and the water would be replaced by a different reduced product.

Question 39

Of the following fermentation pathways, which can be carried out by human muscle cells?

A) lactic acid: heterolactic
B) alcoholic
C) mixed acid
D) lactic acid: homolactic
E) butanediol

Question 40

What are the products made during glycolysis?

A) 4 ATP (net gain of 2) and 2 NADH
B) 2 NADH
C) 4 ATP (net gain of 2)
D) 2 pyruvic acid
E) 4 ATP (net gain of 2) and 2 NADH and 2 pyruvic acid

Question 41

Compare and contrast aerobic cellular respiration, anaerobic cellular respiration, and fermentation in terms of purpose, pathways used, the final electron acceptor, amount of ATP produced, method of phosphorylation to produce ATP, the use of an electron transport chain, the role of oxygen, and the end- products (other than ATP) which are produced.

Question 42

The main energy benefit of the Krebs cycle is the mass production of both ATP and the reduced factors NADH and FADH₂.

Question 43

Describe how organisms can be classified in terms of their nutritional pattern. Specifically categorize organisms in terms of how they obtain organic carbon, the source of electrons for their redox reactions, and the source of energy to make ATP. Finally, use correct terminology to combine these categories to organize the types of organisms by their metabolic strategies.

Question 44

Describe or diagram the relationship between catabolic pathways, anabolic pathways and the ATP- ADP cycle. Include in your answer an explanation of the role each of these plays in the metabolism of a cell.

Question 45

Usually, a single biochemical test is all that is needed to identify an unknown microbial sample.

Question 46

By the end of the Krebs cycle, every carbon originally in glucose is converted into carbon dioxide.

Question 47

Biochemical tests are useful to microbiology because

A) they can be used to identify microbes.
B) they can be used to identify microbes and to identify potential pathogens in clinical samples.
C) they can be used to detect metabolic end- products, intermediates, or particular enzymes.
D) they can be used to identify potential pathogens in clinical samples.
E) they can be used to identify microbes and to identify potential pathogens in clinical samples and they can be used to detect metabolic end- products, intermediates, or particular enzymes.

Question 48

Besides biochemical tests, which techniques are also useful for identifying a bacterial specimen?

A) microscopy and molecular genetics techniques and observation of general culture characteristics
B) observation of general culture characteristics
C) molecular genetics techniques
D) microscopy
E) microscopy and observation of general culture characteristics

Question 49

Generally, purines and pyrimidines are not synthesized de novo but rather obtained through salvage pathways to recycle them from food because de novo synthesis has a high energy cost.

Question 50

Radioactive isotopes of various elements can be used to label molecules for use in studies of metabolic pathways. For example, 14C is a radioactive isotope of carbon and naturally occurs at much lower rates than non- radioactive 12C (i.e. most molecules contain 12C carbon atoms). A cell can be fed a nutrient molecule labeled with the radioactive isotope and scientists can detect where the radioactive isotope ends up. For each of the following scenarios, trace the radioactive isotope to where it ultimately would end up after moving through the cellular respiration, fermentation, or biosynthetic pathways. Only consider these metabolic pathways; do not consider any other cellular processes.
A. E. coli is fed 14C- labeled glucose and grown under aerobic conditions.
B. E. coli is fed 14C- labeled glucose and grown under anaerobic conditions (fermentation).
C. E. coli is fed 14C- labeled fatty acids and grown under aerobic conditions.
D. E. coli is fed 14C- labeled acetyl CoA and grown under conditions that promote biosynthetic pathways.

Question 51

Cells harvest energy from nutrients by stripping electrons from them. In other words, the nutrients are oxidized.

Question 52

Which category of biochemical tests is incorrectly matched with its description?

A) Fermentation tests: Detects various fermentation end- products or specific pathways
B) Oxidase and catalase tests: Identifies the presence of enzymes related to anaerobic respiratory chains
C) Amino acid catabolism tests: Detect specific enzymes involved in catabolism of amino acids
D) Exoenzyme tests: Detect enzymes involved in extra- cellular breakdown of macromolecules
E) Rapid identification techniques: Provides a semi- automated process of running multiple types of tests with a single inoculation

Question 53

Ribozymes are enzymes which are made of protein but only work on RNA molecules as substrates.

Question 54

In chemiosmosis, protons funnel through ATP synthase from an area where they are more concentrated to an area where they are less concentrated.

Question 55

Catabolic reactions are hydrolytic and exergonic while anabolic reactions are biosynthetic and endergonic.

Question 56

Describe two factors which may increase enzyme activity and two factors which may decrease enzyme activity. Explain how each factor works to increase or decrease enzyme activity, and identify whether that factor is used internally by the cell (i.e. for regulation of a chemical reaction) or acts externally (i.e. is a component of the environment or a human- influenced component).

Question 57

The Entner- Doudoroff pathway is a less efficient alternative to glycolysis which likely evolved early in the history of life to catabolize glucose.

Question 58

A bacterial culture which is growing under conditions that only allow for fermentation will grow at the same rate as a culture of the same species growing under conditions which allow for aerobic cellular respiration, all other conditions being identical.

Question 59

What is the advantage of a rapid identification tool such as the API system?

A) allows a high volume of samples to be processed quickly and reliably and can often be read using an automated reader
B) allows a high volume of samples to be processed quickly and reliably and can be inoculated with a mixed or unpurified culture
C) allows a high volume of samples to be processed quickly and reliably
D) can be inoculated with a mixed or unpurified culture
E) can often be read using an automated reader

Question 60

Bacteria that live in deep ocean volcanic vents form the base of an ecosystem that exists without light. They obtain electrons from hydrogen sulfide compounds dissolved in the vent water, and synthesize sugars from carbon, hydrogen, and oxygen. The bacteria would be classified as

A) chemolithoheterotrophs.
B) photolithoautotrophs.
C) photoorganoheterotrophs.
D) chemoorganoheterotrophs.
E) chemolithoautotrophs.