PRACTICE QUIZ CHAP. 9

In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen. The mice were closely monitored, and after a few minutes radioactive oxygen atoms showed up in _____. 1) carbon dioxide 2) NADH 3) water 4) ATP 5) oxygen gas

1

The ATP synthase in a human cell obtains energy for making ATP directly from which of the following processes? 1) the oxidation of NADH and FADH2 2) the flow of H+ across a membrane through the ATP synthase enzyme 3) the oxidation of glucose 4) the movement of electrons through a series of carriers 5) the reduction of oxygen

2

Which of the following accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle? 1) formation of CO2 and ATP 2) formation of CO2 and NADH 3) formation of CO2 and coenzyme A 4) removal of coenzyme A 5) regeneration of NAD+

2

After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of _____. 1) acetyl CoA 2) ATP 3) NADH 4) CO2 5) FADH2

3

The overall efficiency of respiration (the percentage of the energy released that is saved in ATP) is approximately _____. 1) 0.5% 2) 2% 3) 40% 4) 94% 5) 100%

3

A small amount of ATP is made in glycolysis by which of the following processes? 1) transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation 2) harnessing energy from the sun 3) transport of electrons through a series of carriers 4) transfer of electrons and hydrogen atoms to NAD+ 5) attachment of a free inorganic phosphate (Pi) group to ADP to make ATP

1

During respiration in a eukaryotic cell, reactions of glycolysis occur _____. 1) in the cytosol 2) in the matrix of the mitochondrion 3) in the inner membrane of the mitochondrion 4) in the intermembrane space of the mitochondrion 5) across the inner membrane of the mitochondrion

1

During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is reduced as a result of the reaction? During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is reduced as a result of the reaction? 1) oxygen 2) glucose 3) carbon dioxide 4) water 5) both glucose and carbon dioxide

1

A gram of fat oxidized by respiration produces approximately twice as much ATP as a gram of carbohydrate. Which of the following best explains this observation? 1) Fats are produced when cells take in more food than they need. 2) Fats are better electron donors to oxygen than are sugars. 3) Fats are less soluble in water than sugars. 4) Fats do not form true macromolecules as sugars do. 5) Fats are closely related to lipid molecules, the basic building blocks of cellular membranes.

2

In the citric acid cycle, for each pyruvate that enters the cycle, 1 ATP, 3 NADH, and 1 FADH2 are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle? 1) 2 ATP, 6 NADH, 2 FADH2 2) 4 ATP, 6 NADH, 2 FADH2 3) 3 ATP, 3 NADH, 1 FADH2 4) about 38 ATP 5) 1 ATP, 3 NADH, 1 FADH2

1

When protein molecules are used as fuel for cellular respiration, _____ are produced as waste. 1) amino groups 2) fatty acids 3) sugar molecules 4) molecules of lactate 5) ethanol and CO2

1

Which of the following statements provides the best explanation for why the oxidation of organic compounds by molecular oxygen (O2) yields so much energy? 1) The oxygen atom has a higher affinity for electrons than the carbon atom. 2) The reaction has a very negative free-energy change. 3) In cells, this reaction is capable of providing the energy for ATP synthesis. 4) This is an example of a redox reaction, and all redox reactions produce a large amount of energy. 5) Any reaction that produces water as a product will also release a lot of energy.

1

Which one of the following best describes the electron transport chain? 1) Electrons are pumped across a membrane by active transport. 2) Acetyl CoA is fully oxidized to CO2. 3) Hydrogen atoms are added to CO2 to make an energy-rich compound. 4) Electrons are passed from one carrier to another, releasing a little energy at each step. 5) Glucose is broken down to a three-carbon compound in preparation for the citric acid cycle.

4

During respiration in eukaryotic cells, reactions of the citric acid cycle occur _____. 1) in the cytosol 2) in the matrix of the mitochondrion 3) in the cristae of the mitochondrion 4) in the intermembrane space of the mitochondrion 5) across the inner membrane of the mitochondrion

2

Each ATP molecule contains about 1% of the amount of chemical energy available from the complete oxidation of a single glucose molecule. Cellular respiration produces about 38 ATP from one glucose molecule. What happens to the rest of the energy in glucose? 1) It is stored as fat. 2) It is converted to heat. 3) It is used to make water from hydrogen ions and oxygen. 4) It is released as carbon dioxide and water 5) It is converted to starch.

2

How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen? 1) 2 2) 4 3) 3 4) about 38 ATP 5) none of the above

2

Most of the ATP produced in cellular respiration comes from which of the following processes? 1) glycolysis 2) oxidative phosphorylation 3) reduction of NADH 4) substrate-level phosphorylation 5) the citric acid cycle

2

Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of which of the following compounds? 1) ATP 2) lactate 3) carbon dioxide 4) ADP 5) oxygen

2

A molecule becomes more oxidized when it _____. 1) changes shape 2) gains a hydrogen (H+) ion 3) loses a hydrogen (H+) ion 4) gains an electron 5) loses an electron

5

A chemist has discovered a drug that blocks phosphoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to kill bacteria in people with infections. However, he cannot do this because _____. 1) bacteria are prokaryotes; they usually don't need to perform glycolysis 2) glycolysis produces so little ATP that the drug will have little effect 3) human cells must also perform glycolysis; the drug might also poison them 4) this step in the pathway of glycolysis can be skipped in bacteria, but not in humans 5) glycolysis can occur without the action of enzymes

3

During respiration in eukaryotic cells, the electron transport chain is located in or on the _____. 1) cytosol 2) matrix of the mitochondrion 3) inner membrane of the mitochondrion 4) intermembrane space of the mitochondrion 5) none of the above

3

Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step _____. 1) removes poisonous oxygen from the environment 2) extracts a bit more energy from glucose 3) enables the cell to recycle NAD+ 4) prevents pyruvate from accumulating 5) enables the cell to make pyruvate into substances it can use

3

In brewing beer, maltose (a disaccharide of glucose) is _____. 1) a flavoring ingredient 2) the substrate for aerobic respiration 3) the substrate for alcoholic fermentation 4) one of the enzymes for alcoholic fermentation 5) a substitute for pyruvate that cannot be made in yeast

3

In glycolysis in the absence of oxygen, cells need a way to regenerate which compound? 1) ethanol 2) carbon dioxide 3) NAD+ 4) lactate 5) glucose

3

In glycolysis, there is no production of carbon dioxide as a product of the pathway. Which of the following is the best explanation for this? 1) There are no oxidation or reduction reactions in glycolysis to produce CO2. 2) There is very little ATP produced in glycolysis. 3) The two pyruvate molecules produced from each glucose molecule each contain three carbon atoms. 4) The initial steps of glycolysis require an input of energy in the form of ATP (two per glucose). 5) none of the above

3

In the overall process of glycolysis and cellular respiration, _____ is oxidized and _____ is reduced. 1) oxygen; ATP 2) ATP; oxygen 3) glucose; oxygen 4) carbon dioxide; water 5) glucose; ATP

3

The energy given up by electrons as they move through the electron transport chain is used in which of the following processes? 1) the breakdown of glucose 2) the production of NADH and FADH2 3) pumping H+ across a membrane 4) the oxidation of water 5) the production of CO2

3

The function of cellular respiration is to _____. 1) reduce CO2 2) extract CO2 from the atmosphere 3) extract usable energy from glucose 4) synthesize macromolecules from monomers 5) produce carbohydrates

3

What is the name of the process in which glucose is converted to pyruvate with the production of ATP and NADH? 1) chemiosmosis 2) fermentation 3) glycolysis 4) the citric acid cycle 5) none of the above

3

When a poison such as cyanide blocks the electron transport chain, glycolysis and the citric acid cycle soon grind to a halt as well. Which of the following is the best explanation for this? 1) A high level of NADH is present in the cell. 2) The uptake of oxygen stops because electron transport was inhibited. 3) NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue. 4) Electrons are no longer available from the electron transport chain to power glycolysis and the citric acid cycle. 5) They run out of ADP.

3

Which of the following represents the major (but not the only) energy accomplishment of the citric acid cycle? 1) formation of CO2 2) formation of ATP 3) formation of NADH and FADH2 4) utilization of O2 5) completion of substrate-level phosphorylation

3

Which of the following sequences correctly describes the synthesis of ATP associated with electron transport in mitochondria? 1) NADH, electron transport, chemiosmosis, proton gradient 2) NADH, electron transport, proton gradient, substrate-level phosphorylation 3) NADH, electron transport, proton gradient, chemiosmosis 4) NADH, electron transport, substrate-level phosphorylation, ATP 5) None of the above correctly shows the pattern of energy flow between electron transport and ATP synthesis.

3

Why is the citric acid cycle called a cycle? 1) The pyruvate that enters the cycle is regenerated in the last step of the pathway. 2) NAD+ and FAD are recycled. 3) The four-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the cycle. 4) All of the carbon from glucose is cycled back into the atmosphere as carbon dioxide. 5) NADH is cycled down the electron transport chain.

3

Most of the electrons removed from glucose by cellular respiration are used for which of the following processes? 1) reducing NAD+ to NADH in glycolysis and the citric acid cycle 2) producing a proton gradient for ATP synthesis in the mitochondria 3) driving substrate-level phosphorylation in glycolysis 4) The first two choices are correct. 5) The first three answers are correct.

4

Of the following molecules in the glycolytic pathway (the process of glycolysis), the one with the most chemical energy is _____. 1) pyruvate 2) glucose 3) fructose-6-phosphate 4) fructose-1,6-bisphosphate 5) glyceraldehyde-3-phosphate

4

Of the metabolic pathways listed below, which is the only pathway found in all organisms? 1) cellular respiration 2) the citric acid cycle 3) the electron transport chain 4) glycolysis 5) fermentation

4

Oxygen gas (O2) is one of the strongest oxidizing agents known. The explanation for this is that _____. 1) oxygen is so abundant in the atmosphere 2) oxygen gas is composed of two atoms of oxygen 3) oxygen gas contains a double bond 4) the oxygen atom is very electronegative 5) oxygen acts as the final electron acceptor in cellular respiration

4

During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes? 1) at the end of glycolysis to oxidize pyruvate 2) at the end of the citric acid cycle to regenerate citric acid 3) between glycolysis and the citric acid cycle to split a carbon from pyruvate, producing CO2 4) as a source of O2 in every reaction that produces CO2 5) at the end of the electron transport chain to accept electrons and form H2O

5

If a compound that allows protons to freely diffuse across membranes is added to cells that are actively metabolizing glucose via cellular respiration, which of the following processes would stop? 1) glycolysis 2) electron transport 3) ATP synthesis 4) all of the above 5) none of the above

5

If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result? 1) The muscle cells will have more trouble making enough ATP to meet their energy requirements. 2) The cells will not be able to carry out oxidative phosphorylation. 3) The cells will consume glucose at an increased rate. 4) Only the first two answers are correct. 5) The first three answers are correct.

5

If significant amounts of materials are removed from the citric acid cycle to produce amino acids for protein synthesis, which of the following will result? 1) Less ATP will be produced by the cell. 2) Less CO2 will be produced by the cell. 3) The four-carbon compound that combines with acetyl CoA will have to be made by some other process. 4) The first two answers are correct. 5) The first three answers are correct.

5

In preparing pyruvate to enter the citric acid cycle, which of the following steps does occur? 1) It is oxidized, and the resulting electrons reduce an NAD+ to an NADH. 2) A carbon atom is released in carbon dioxide. 3) A compound called coenzyme A binds to a two-carbon fragment. 4) None of the above are steps in the metabolism of pyruvate before its entry into the citric acid cycle. 5) The three steps above are all involved in the metabolism of pyruvate before its entry into the citric acid cycle.

5

Most of the NADH that delivers electrons to the electron transport chain comes from which of the following? Most of the NADH that delivers electrons to the electron transport chain comes from which of the following? 1) oxidative phosphorylation 2) substrate-level phosphorylation 3) glycolysis 4) anabolic pathways 5) the citric acid cycle

5

Muscle tissues make lactate from pyruvate to do which of the following? 1) speed up the rate of glycolysis 2) get rid of pyruvate produced by glycolysis 3) utilize the energy in pyruvate 4) produce additional CO2 5) regenerate NAD+

5

Which of the following substances, if any, is/are involved in oxidative phosphorylation? 1) ADP 2) oxygen 3) ATP 4) none of the above 5) The first three choices above are involved in oxidative phosphorylation.

5

Which one of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria? 1) ATP 2) an ATP-dependent proton pump 3) the production of NADH 4) the components of the electron transport chain 5) electrons moving down the electron transport chain

5

Which part of the cellular catabolism of glucose requires molecular oxygen (O2) and produces CO2? 1) glycolysis 2) the citric acid cycle 3) the electron transport chain 4) the combination of glycolysis and the citric acid cycle 5) the combination of the citric acid cycle and electron transport

5