Deck 9: Cellular Respiration and Fermentation

Question 1

Glycolysis is active when cellular energy levels are _____;the regulatory enzyme,phosphofructokinase,is _____ by ATP.

A)low;activated
B)low;inhibited
C)high;activated
D)high;inhibited

Answer 1

B

Question 2

The glucose molecule has a large quantity of energy in its _____.

A)C-H bonds
B)C-N bonds
C)number of oxygen atoms
D)polar structure

Answer 2

A

Question 3

Which of the following events takes place in the electron transport chain?

A)breakdown of glucose into two pyruvate molecules
B)the breakdown of an acetyl group to carbon dioxide
C)the extraction of energy from high-energy electrons remaining from glycolysis and the Krebs cycle
D)substrate-level phosphorylation

Answer 3

C

Question 4

What is the function of coenzyme A in the Krebs cycle?

A)It is the coenzyme of carboxylation reactions.
B)It is the coenzyme of redox reactions.
C)It is a coenzyme of decarboxylation reactions.
D)It is the coenzyme of acetylation reactions.

Question 5

A substrate-level phosphorylation occurs in the Krebs cycle when _____.

A)GDP is phosphorylated to produce GTP
B)NAD⁺ is phosphorylated to NADH
C)oxaloacetate is phosphorylated
D)acetylation of oxaloacetate takes place

Question 6

Substrate-level phosphorylation occurs within a metabolic pathway where sufficient energy is released by a given chemical reaction to drive the synthesis of ATP from ADP and phosphate.In which of the following metabolic pathways is substrate-level phosphorylation exhibited?

A)in glycolysis
B)in the Krebs cycle
C)in both glycolysis and the Krebs cycle
D)during oxidative phosphorylation

Question 7

The enzyme phosphofructokinase is the major regulatory enzyme of glycolysis.It catalyzes _____.

A)the phosphorylation of ADP to ATP
B)the isomerization of glucose 6-phosphate to fructose 6-phosphate
C)the phosphorylation of fructose 6-phosphate
D)the substrate-level phosphorylation reaction whereby phosphoenolpyruvate is converted to pyruvate

Question 8

Most of the CO₂ from the catabolism of glucose is released during _____.

A)glycolysis
B)electron transport
C)chemiosmosis
D)the Krebs cycle

Question 9

If you were to add one of the eight Krebs cycle intermediates to the culture medium of yeast growing in the laboratory,what do you think would happen to their rates of ATP and carbon dioxide production?

A)There would be no change in ATP production,but we would observe an increased rate of carbon dioxide production.
B)The rates of ATP production and carbon dioxide production would both increase.
C)The rate of ATP production would decrease,but the rate of carbon dioxide production would increase.
D)Rates of ATP and carbon dioxide production would probably both decrease.

Question 10

A cell has enough available ATP to meet its needs for about 30 seconds.What is likely to happen when an athlete exhausts his or her ATP supply?

A)He or she has to sit down and rest.
B)Catabolic processes are activated that generate more ATP.
C)ATP is transported into the cell from the circulatory system.
D)Other cells take over,and the muscle cells that have used up their ATP cease to function.

Question 11

Following glycolysis and the Krebs cycle,but before the electron transport chain and oxidative phosphorylation,the carbon skeleton of glucose has been broken down to CO₂ with some net gain of ATP.Most of the energy from the original glucose molecule at that point in the process,however,is in the form of _____.

A)acetyl-CoA
B)glucose
C)pyruvate
D)NADH

Question 12

Two ATP molecules are expended in the energy investment phase of glycolysis.Why is this energy needed to begin the process of glucose catabolism?

A)It is needed because glycolysis is considered an exergonic process which always requires input of energy from ATP.
B)It is needed to generate the electron carrier NAD⁺.
C)It is needed to induce the enzymes of glycolysis.
D)Some energy must be invested to make the glucose molecule unstable and begin the process of catabolism.

Question 13

Refer to Figure 9.1 in the text.What characteristic of this molecule (ATP)is responsible for its high energy level?

A)the three phosphate groups
B)the phosphorus atoms in the phosphate groups
C)the C-H bonds of the ribose sugar
D)the closely spaced negative charges associated with the phosphate groups

Question 14

The first CO₂ that is released during aerobic cellular respiration is _____.

A)during glycolysis
B)between glycolysis and the Krebs cycle
C)during the Krebs cycle
D)just after the Krebs cycle

Question 15

Why might adding inorganic phosphate to a reaction mixture where glycolysis is rapidly proceeding help sustain the metabolic pathway?

A)It would increase the amount of glucose available for catabolism.
B)It would increase the oxygen supply available for aerobic respiration because each phosphate group contains four oxygen atoms as constituents.
C)The metabolic intermediates of glycolysis are phosphorylated.
D)It increases the energy level of the electrons that are transferred to the electron transport chain where ATP is produced.

Question 16

C₆H₁₂O₆ (glucose)+ 6 O₂ → 6 CO₂ + 6 H₂O
Where is most of the water in this reaction produced?

A)during glycolysis
B)in the Krebs cycle
C)during fermentation
D)in the electron transport chain

Question 17

Which of the following statements about cellular metabolism is false?

A)Glycolysis is inhibited when cellular energy levels are abundant.
B)Krebs cycle activity is dependent solely on availability of substrate;otherwise it is unregulated.
C)In the electron transport chain,electrons decrease in energy level as they are transferred from one electron carrier to the next.
D)Reactions of the Krebs cycle take place in the mitochondrial matrix.

Question 18

Which electron carrier(s)function in the Krebs cycle?

A)NAD⁺ only
B)both NAD⁺ and FAD
C)the electron transport chain
D)NADH and FADH₂

Question 19

Canine phosphofructokinase (PFK)deficiency afflicts springer spaniels,affecting an estimated 10% of the breed.PFK is the glycolytic enzyme that phosphorylates fructose-1-phosphate and catalyzes the committed step in glycolysis.Given its critical role in glycolysis,one implication of the genetic defect resulting in PFK deficiency in dogs is _____.

A)early embryonic mortality
B)elevated blood-glucose levels in the dog's blood
C)an intolerance for exercise
D)a reduced life span

Question 20

In the energy-yielding phase of glycolysis,energy is extracted in the form of _____.

A)pyruvate
B)ATP
C)NADH
D)ATP and NADH

Question 21

Fatty acids usually have an even number of carbons in their structures.They are catabolized by a process called beta-oxidation.The end products of the metabolic pathway are acetyl groups of acetyl CoA molecules.What is the most likely fate of the acetyl groups?

A)They directly enter the electron transport chain.
B)They directly enter the energy-yielding stages of glycolysis.
C)They are directly decarboxylated by pyruvate dehydrogenase.
D)They directly enter the Krebs cycle.

Question 22

The constituents of the electron transport chain have similar capabilities,with the exception of ubiquinone (coenzyme Q).What is different about ubiquinone?

A)Ubiquinone is a protein that begins the electron transport chain,so it accepts the highest-energy electrons.
B)Ubiquinone is a protein that serves as a regulator of the rate of redox reactions in the electron transport chain.
C)Ubiquinone is a protein that is a constituent of all cells,prokaryotic or eukaryotic;hence its name originating from "ubiquitous."
D)Ubiquinone is lipid soluble and so can move through the inner mitochondrial membrane.

Question 23

Why are fermentation reactions important for cells?

A)They produce alcohol which enhances the permeability of their mitochondrial membranes to proton translocation.
B)They regenerate NAD⁺ so that glycolysis can continue to operate.
C)They allow the cell to conserve oxygen for the Krebs cycle.
D)They generate oxygen.

Question 24

The energy of electron transport serves to move (translocate)protons to the outer mitochondrial compartment.How does this help the mitochondrion to produce energy?

A)The hydrogen ions (protons)are transferred to oxygen in an energy-releasing reaction.
B)The translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria.
C)The protons pick up electrons from the electron transport chain on their way through the inner mitochondrial membrane.
D)The protons receive electrons from the NAD⁺ and FAD that are accepted by electrons in glycolysis and the Krebs cycle.

Question 25

The inner mitochondrial membrane normally _____.

A)contains permease channels that allow small ions and water to pass readily through the membrane by simple diffusion
B)contains an active transport pump that pumps protons into the inner mitochondrial compartment from the point of high concentration to a point of lower concentration
C)is virtually impermeable to hydrogen ions (protons)
D)contains enzymes responsible for two of the chemical reactions that take place as part of glycolysis

Question 26

The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because _____.

A)it explains how ATP is synthesized by a proton motive force
B)it explains how electron transport can fuel substrate-level phosphorylation
C)it explains the sequence of the electron transport chain molecules
D)it explains the reduction of oxygen to water in the final steps of oxidative metabolism

Question 27

The electron transport chain _____.

A)is a series of redox reactions
B)is a series of substitution reactions
C)is driven by ATP consumption
D)takes place in the cytoplasm of prokaryotic cells