micro chapter 6

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1

1. Experiments designed by ______________ suggested that living cells caused the fermentation of sugar to produce alcohol.
A. Pasteur
B. Koch
C. Wohler
D. Fleming

A. Pasteur

2

2. Studies done by Buchner showed that ground-up yeast cells were able to convert sugar to alcohol. The components of the mixture that were responsible for this transformation were
A. DNA molecules.
B. enzymes.
C. lipids.
D. carbohydrates.

B. enzymes.

3

3. Concerning catabolism and anabolism,
A. they refer to reactions solely dealing with the metabolism of lipids.
B. the intermediates of one serve as the reactants in the other.
C. the energy gathered in one is utilized in the other.
D. they refer solely to the reactions involved in synthesis of carbohydrates.
E. the intermediates of one serve as the reactants in the other AND the energy gathered in one is utilized in the other.

E. the intermediates of one serve as the reactants in the other AND the energy gathered in one is utilized in the other.

4

4. The general term used to describe the anabolic and catabolic reactions in a cell is
A. enzymatic.
B. thematic.
C. aerobic respiration.
D. metabolism.

D. metabolism.

5

5. Energy is defined as
A. water flowing up a dam.
B. the capacity to do work.
C.

the use of high-level phosphate bonds.

D. the potential to fall.

B. the capacity to do work.

6

6. Biosynthetic reactions that require energy for the conversion of molecular subunits into larger molecules are called
A. kinetic energy.
B. catabolic reactions.
C. precursor molecules.
D. anabolic reactions.

D. anabolic reactions.

7

7. Exergonic reactions
A. occur when there is more free energy in the products than the reactants.
B. occur when there is more free energy in the reactants than the products.
C. are defined as a decrease in entropy.
D. are chemoorganotrophic.

B. occur when there is more free energy in the reactants than the products.

8

8. Free energy
A. includes the energy lost as heat.
B. is the amount of energy gained by breaking bonds of a chemical.
C. differs for a given reaction depending on the number of steps involved.
D. always results in a decrease in total energy.
E. is the amount of energy gained by breaking bonds of a chemical AND differs for a given reaction depending on the number of steps involved.

B. is the amount of energy gained by breaking bonds of a chemical.

9

9. Bacteria that can absorb light energy and convert it into ATP are commonly called
A. cytochromes.
B. lysosomes.
C. chemotrophs.
D. phototrophs.
E. cytochromes AND chemotrophs.

D. phototrophs.

10

10. The readily usable energy currency of cells is
A. electricity.
B. the electron transport system.
C. ATP.
D. CTP.
E. the electron transport system AND CTP.

C. ATP

11

11. Each of the following statements about chemoorganotrophs is true EXCEPT:
A. They may use substrate-level phosphorylation to produce ATP.
B. They may use oxidative phosphorylation to produce ATP.
C. They may use photophosphorylation to produce ATP.

D. They utilize an electrochemical gradient.

C.

They may use photophosphorylation to produce ATP.

12

12. The name given to the reaction involving removal of electrons or hydrogen atoms from a compound is termed
A. glycolysis.
B. reduction.
C. oxidation.
D. metabolism.

C. oxidation.

13

13. The name given to the reaction involving addition of electrons or hydrogen atoms to a compound is termed
A. glycolysis.
B. reduction.
C. oxidation.
D. metabolism.

B. reduction.

14

NAD in its reduced form is abbreviated as

A. NADH.
B. NAD.
C. NAD-.
D. NADP.

A. NADH.

15

15. Glycolysis
A. is also known as the Embden-Meyerhof-Parnas pathway.
B. is also known as the Entner-Duodoroff pathway.
C. is used by Pseudomonas and a few other bacteria.
D. generates some energy and NADPH.
E. is also known as the Entner-Duodoroff pathway AND is used by Pseudomonas and a few other bacteria.

A. is also known as the Embden-Meyerhof-Parnas pathway.

16

16. The most common starting pathway for the breakdown of sugars is
A. respiration.
B. fermentation.
C. glycolysis.
D. oxidation.

C. glycolysis.

17

17. Glycolysis, the Entner-Duodoroff pathway and the pentose phosphate pathway all produce
A. pyruvate.
B. NAD.
C. NADP.
D. acetyl-CoA.

A. pyruvate.

18

18. Cells degrade sugar largely to
A. gain energy.
B. use energy.
C. convert fat to energy.
D. utilize coenzymes.

A. gain energy.

19

19. Oxygen serves as the terminal electron acceptor in
A. fermentation.
B. aerobic respiration.
C. anaerobic respiration.
D. reduction.

B. aerobic respiration.

20

20. The terminal electron acceptor in respiration may be
A. oxygen.
B. nitrate.
C. NAD.
D. an inorganic molecule.
E.

oxygen, nitrate, AND an inorganic molecule.

E.

oxygen, nitrate, AND an inorganic molecule.

21

21. Which of the following processes generates the greatest amount of energy?
A.

Fermentation

B.

Aerobic respiration

C.

The Entner-Duodoroff pathway

D.

Glycolysis

E.

Fermentation AND the Entner-Duodoroff pathway

B.

Aerobic respiration

22

22. Fermentation
A. uses an inorganic molecule as the final electron acceptor.
B. uses an organic molecule as the final electron acceptor.
C. results in the production of a large amount of ATP.
D. is necessary in some organisms to produce reduced electron carriers.
E. uses an organic molecule as the final electron acceptor AND is necessary in some organisms to produce reduced electron carriers.

B. uses an organic molecule as the final electron acceptor.

23

23. Which is/are true regarding organic acids?
A. They are weak acids.
B. They are often involved in metabolic reactions.
C. They often exist in the ionized form at the near-neutral pH found in a cell.
D. Pyruvate and pyruvic acid refer to different forms of the same substance.
E. All of the choices are true.

E. All of the choices are true.

24

24. Pyruvate can be metabolized along two major routes. They are
A. oxidation and reduction.
B. fermentation and respiration.
C. metabolism and anabolism.
D. anabolism and catabolism.

B. fermentation and respiration.

25

25. The use of the suffix "ase" on a word denotes a(n)
A. substrate.
B. product.
C. enzyme.
D. electron acceptor.
E. substrate AND electron acceptor.

C. enzyme.

26

26. Enzymes act as
A. substrates.
B. catalysts.
C. products.
D. catabolites.

B. catalysts.

27

27.

Enzymes act on _______ to generate ________.

A.

Products, catabolites

B.

Substrates, products

C.

Products, substrates

D.

Glucose, anabolites

B.

Substrates, products

28

28. Enzymes speed up reactions by
A. raising activation energy.
B. producing heat.
C. reducing entropy.
D. lowering activation energy.
E. raising activation energy AND reducing entropy.

D. lowering activation energy.

29

29. The mutual interaction of substrate and enzyme is described as a(n)
A. lock and key arrangement.
B. induced fit.
C. active site.
D. allosteric site.
E. active site AND allosteric site.

B. induced fit.

30

30. Most enzymes
A.

are generic, typically recognizing a number of different substrates.

B.

are specific, typically recognizing a single or a few substrates.

C. are active over a wide pH range.
D.

are active over a wide temperature range.

E.

are generic, typically recognizing a number of different substrates AND are active over a wide pH range.

B.

are specific, typically recognizing a single or a few substrates.

31

31. Allosteric enzymes
A. may bind two substrates.
B. are used to bind to other enzymes.
C. have an additional binding site that is involved in regulating enzyme activity.

C. have an additional binding site that is involved in regulating enzyme activity.

32

32. Feedback inhibition
A. is a means of regulating the amount of product produced.
B. often involves the use of allosteric enzymes.
C. involves inhibiting the last of a series of reactions.
D. results in raising the activation energy for the reaction.
E. is a means of regulating the amount of product produced AND often involves the use of allosteric enzymes.

E. is a means of regulating the amount of product produced AND often involves the use of allosteric enzymes.

33

33. Coenzymes are derivatives of
A. minerals.
B. proteins.
C. lipids.
D. vitamins.

D. vitamins.

34

34. The small, non-protein molecules that can be readily separated from an enzyme and are responsible for transfer of atoms from one molecule to another are referred to as
A. vitamins.
B. enzymes.
C. hormones.
D. coenzymes.

D. coenzymes.

35

35. Which is/are true of coenzymes?
A. They are organic molecules.
B. They transfer atoms from one molecule to another.
C. They may bind to a number of different enzymes.
D. They are synthesized from vitamins.
E. All of the choices are correct.

E. All of the choices are correct.

36

36. Environmental factors that may affect enzyme activity include
A.

temperature.

B.

pH.

C.

salt.

D.

temperature, pH, AND salt.

D.

temperature, pH, AND salt.

37

37. Most enzymes function best at
A. acidic pH and high salt concentrations.
B. basic pH and low salt concentrations.
C. neutral pH and high salt concentrations.
D. slightly above pH 7 and low salt concentrations.

D. slightly above pH 7 and low salt concentrations.

38. Which is true of competitive inhibition?
A. It involves an allosteric enzyme.
B. Substrate and inhibitor both bind to the active site.
C.

A sulfa antibiotic is a competitive inhibitor.

D. Mercury is a competitive inhibitor.
E.

Substrate and inhibitor both bind to the active site AND a sulfa antibiotic is a competitive inhibitor.

38

38. Which is true of competitive inhibition?
A. It involves an allosteric enzyme.
B. Substrate and inhibitor both bind to the active site.
C.

A sulfa antibiotic is a competitive inhibitor.

D. Mercury is a competitive inhibitor.
E.

Substrate and inhibitor both bind to the active site AND a sulfa antibiotic is a competitive inhibitor.

E.

Substrate and inhibitor both bind to the active site AND a sulfa antibiotic is a competitive inhibitor.

39

39. Mercury in mercurochrome inhibits growth
A. through competitive inhibition.
B. through a reversible action.
C. by oxidizing the sulfhydryl groups in cysteine.
D. by changing the shape of proteins.
E. by oxidizing the sulfhydryl groups in cysteine AND by changing the shape of proteins.

E. by oxidizing the sulfhydryl groups in cysteine AND by changing the shape of proteins.

40

The term "precursor metabolite" refers to molecules that

A. activate cell components.
B. are used in biosynthesis.
C. result from cell activities.
D. are present but inactive.

B. are used in biosynthesis.

41

41. Which is true regarding the three central metabolic pathways?
A.

They form high-energy bonds that can be used to synthesize ATP.

B. They form intermediates that can be oxidized to generate reducing power.
C. They form precursor metabolites.
D. All of the choices are correct.

D. All of the choices are correct.

42

42. Glycolysis
A. requires oxygen.
B.

produces 3 ATP molecules per molecule glucose.

C.

produces 4 molecules of NAD per molecule glucose.

D. may occur under aerobic or anaerobic conditions.
E.

produces 3 ATP molecules AND produces 4 molecules of NAD per molecule glucose.

D. may occur under aerobic or anaerobic conditions.
E.

43

43. The energy yield of any energy-transforming pathway
A. is fixed.
B. is variable depending on the type of enzymes used.
C. is variable depending on the amount of precursor metabolites removed for biosynthesis.
D. is fixed by the amount of oxygen available.

C. is variable depending on the amount of precursor metabolites removed for biosynthesis.

44

44. The transition step
A. links glycolysis to the pentose phosphate pathway.
B. links the pentose phosphate pathway to the Entner-Duodoroff pathway.
C. links glycolysis to the TCA cycle.
D. takes place in the matrix of the nucleus.

C. links glycolysis to the TCA cycle.

45

45. The TCA cycle produces
A. ATP through substrate-level phosphorylation.
B. NADH.
C. FADH2.
D. precursor metabolites.
E. All of the choices are correct.

E. All of the choices are correct.

46

46. What happens to the carbon molecules in the pyruvic acid that goes through the TCA cycle?
A. They get incorporated into cell material.
B. They are excreted as waste organic acids.
C. They become carbon dioxide.
D. They form "energy storage molecules" and are stored by the cell.

C. They become carbon dioxide.

47

47. The electron transport system
A. requires a membrane.
B. utilizes the nuclear membrane of eukaryotes.
C. utilizes the mitochondrial membrane of prokaryotes.
D. generates a concentration gradient of protons.
E. requires a membrane AND generates a concentration gradient of protons.

E. requires a membrane AND generates a concentration gradient of protons.

48

48. Which type of phosphorylation does not require a membrane?
A. Substrate-level phosphorylation
B. Oxidative phosphorylation
C. Photophosphorylation
D. All types of phosphorylation require a membrane.

A. Substrate-level phosphorylation

49

49. In the electron transport system
A. NADH and FADH2 both donate electrons at the same location.
B. NADH donates electrons "upstream" of where FADH2 donates electrons.
C. NAD donates electrons at the head of the chain.
D. NADP donates electrons in the middle of the chain.

B. NADH donates electrons "upstream" of where FADH2 donates electrons.

50

50. Proton motive force
A. is used to synthesize ATP.
B. is used to drive flagella rotation.
C. is used to produce NADH.
D. is used to produce FADH2.
E. is used to synthesize ATP AND is used to drive flagella rotation.

E. is used to synthesize ATP AND is used to drive flagella rotation.

51

51. In the phototrophic production of energy, the oxygen originates from
A. carbon dioxide.
B. water.
C. glucose.
D. hydrogen peroxide.

B. water.

52

52. Anoxygenic photosynthetic bacteria
A. obtain electrons from water.
B.

do not produce oxygen as a by-product.

C. may obtain electrons from H2S.
D. are obligate aerobes.
E.

do not produce oxygen as a by-product AND may obtain electrons from H2S.

E.

do not produce oxygen as a by-product AND may obtain electrons from H2S.

53

53. The sugar component of RNA and DNA nucleotides are synthesized
A. as deoxyribose and then changed to ribose.
B. as ribose and then changed to deoxyribose.
C. separately.
D. using the Calvin cycle.
E. as deoxyribose and then changed to ribose AND using the Calvin cycle.

B. as ribose and then changed to deoxyribose.

54

64.

Fermentation is sometimes used as a means of slowing food spoilage. Why would fermentation lead tothis outcome?

A. Fermentation is THE process that directly reduces sugars in food. Without sugars, bacteria cannot grow and spoil the food.
B. Fermentation will lead to production of high levels of ethanol (95% or higher!)-ethanol will kill bacteria.
C.

Fermentation will lead to production of acidic by-products, dropping the pH of the food below a level that bacteria can tolerate.

D. This is a trick question-fermentation actually IS food spoilage and cannot be used to prevent it under any circumstances.

C.

Fermentation will lead to production of acidic by-products, dropping the pH of the food below a level that bacteria can tolerate.

55

65. Why would a cell ferment rather than respire?
A. There's no oxygen present, and it cannot respire anaerobically.
B. It lacks the ability to respire (i.e. no electron transport chain).
C.

There is no oxygen present and it cannot use anaerobic respiration OR it lacks the ability to respire (i.e., no electron transport chain).

C.

There is no oxygen present and it cannot use anaerobic respiration OR it lacks the ability to respire (i.e., no electron transport chain).

56

66. How would cellulose-degrading bacteria in the rumen (stomachs) of a cow benefit the animal?
A.

The bacteria would produce, secrete, and incorporate organic molecules as they obtain energy from the cellulose in grass and replicate. The cow could then digest both the secreted organic molecules AND the bacteria that synthesized them.

B. The bacteria would produce sugars as they digested the cellulose. These sugars would be given off to the cow as a symbiotic relationship in exchange for the protected location of the stomachs of the cow for the bacteria to grow and replicate in.
C. They wouldn't benefit the animal-they would replicate and cause disease in the animal, leading to its death.
D. They wouldn't benefit the animal-only the bacteria within the animal. This is why cows must have food sources other than grass in order to survive.

A.

The bacteria would produce, secrete, and incorporate organic molecules as they obtain energy from the cellulose in grass and replicate. The cow could then digest both the secreted organic molecules AND the bacteria that synthesized them.

57

A worker in a cheese-making facility argued that whey, a nutrient-rich by-product of the process, should be dumped into a nearby pond to serve as fish food.Is this a good idea or a bad one, and why?

A. It's a great idea! Let's feed the fish and help them multiply!
B. Bad idea-the fish won't be able to eat the whey, so it will sit there rotting and pollute the waters, making them uninhabitable for the fish.
C. Bad idea-bacteria would thrive on this rich nutrient source and multiply readily. As they multiply, they'll use the oxygen in the water to harvest the energy from the whey, depleting it. As the oxygen depletes below a certain point, the fish (and perhaps other organisms) will not be able to survive.
D. Great idea! This will not only feed the fish, but also microbes and other small organisms. It'll enhance the entire food chain and help all of them!

C. Bad idea-bacteria would thrive on this rich nutrient source and multiply readily. As they multiply, they'll use the oxygen in the water to harvest the energy from the whey, depleting it. As the oxygen depletes below a certain point, the fish (and perhaps other organisms) will not be able to survive.

58

68. A student argued that aerobic and anaerobic respiration should produce the same amount of energy. He argued that both processes are essentially the same-only the terminal electron acceptor is different. What's wrong with his argument?
A. Nothing-they SHOULD both produce the same amount of energy. Clearly he knows more than his professors or the writers of his textbook.
B.

Not all electrons are brought into the electron transport chain with the same amounts of potential energy. NADH, for example, enters the electron transport chain "further up" than FADH2-so it will lead to less proton motive force being generated, and thus less eventual ATP.

C.

Not all electron acceptors are the same-some are closer in terms of electronegativity to their high-energy electron carrier molecules (e.g., NADH) than others. The amount of energy that can eventually be obtained is directly proportional to the degree of difference in electronegativity between the high-energy electron carrier and the eventual terminal electron acceptor. The greater the difference, the greater the energy obtained. Oxygen typically has the highest electron affinity of the terminal electron acceptors utilized.

D. He should believe what his instructors tell him, without question-and they say aerobic respiration is better, so it MUST be so.

C.

Not all electron acceptors are the same-some are closer in terms of electronegativity to their high-energy electron carrier molecules (e.g., NADH) than others. The amount of energy that can eventually be obtained is directly proportional to the degree of difference in electronegativity between the high-energy electron carrier and the eventual terminal electron acceptor. The greater the difference, the greater the energy obtained. Oxygen typically has the highest electron affinity of the terminal electron acceptors utilized.

59

69. Chemolithotrophs near hydrothermal vents support a variety of life forms. Why is this analogous to photosynthetic microbes supporting life forms closer to the surface of the planet?
A.

Because all life forms need some energy source, electron source, and carbon source. Chemolithotrophs fix inorganic carbon and, if consumed by other microbes, could serve as sources for all three requirements for life. This is very similar to the role that photosynthetic microbes play in the top levels of the oceans/lakes.

B. Because chemolithotrophs will also utilize energy from sunlight to form their sugars/get their chemical energy...much like photosynthetic microbes.
C. Because chemolithotrophs also pull in carbon dioxide as their carbon source, just like photosynthetic microbes.
D. Because photosynthetic microbes utilize heat energy from the sun as an energy source. Chemolithotrophs utilize heat energy from hydrothermal vents, but it's still heat energy. This makes both microbes similar.

A.

Because all life forms need some energy source, electron source, and carbon source. Chemolithotrophs fix inorganic carbon and, if consumed by other microbes, could serve as sources for all three requirements for life. This is very similar to the role that photosynthetic microbes play in the top levels of the oceans/lakes.