Biology Test 3

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the

transfer of phosphate to ADP.
affinity of oxygen for electrons.
flow of electrons down the electron transport chain.
H+ concentration across the membrane holding ATP synthase.
oxidation of glucose and other organic compounds.

H+ concentration across the membrane holding ATP synthase.

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

synthesis of acetyl CoA from pyruvate
the citric acid cycle
reduction of pyruvate to lactate
the electron transport chain
glycolysis

glycolysis

In mitochondria, exergonic redox reactions

are coupled via phosphorylated intermediates to ender-gonic processes.
are the source of energy driving prokaryotic ATP synthesis.
reduce carbon atoms to carbon dioxide.
provide the energy that establishes the proton gradient.
are directly coupled to substrate-level phosphorylation.

provide the energy that establishes the proton gradient.

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

water.
NAD+.
pyruvate.
oxygen.
ADP.

oxygen.

What is the oxidizing agent in the following reaction?
Pyruvate + NADH + H+ S Lactate + NAD+

NAD+
lactate
pyruvate
oxygen
NADH

pyruvate

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

The cytochromes phosphorylate ADP to form ATP.
NAD+ is oxidized.
ATP synthase pumps protons by active transport.
The pH of the matrix increases.
The electrons gain free energy.

The pH of the matrix increases.

Most CO2 from catabolism is released during

lactate fermentation.
the citric acid cycle.
glycolysis.
electron transport.
oxidative phosphorylation.

the citric acid cycle.

A molecule becomes more oxidized when it _____. ( Concept 9.1)

changes shape
gains a hydrogen (H+) ion
loses a hydrogen (H+) ion
loses an electron
gains an electron

loses an electron

In the overall process of glycolysis and cellular respiration, _____ is oxidized and _____ is reduced. (Concept 9.1)

glucose … ATP
oxygen … ATP
carbon dioxide … water
ATP … oxygen
glucose … oxygen

glucose … oxygen

Most of the ATP produced in cellular respiration comes from which of the following processes? (Concept 9.1)

the citric acid cycle
substrate-level phosphorylation
glycolysis
reduction of NADH
oxidative phosphorylation

oxidative phosphorylation

Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration? ( Concept 9.1)

oxidation of pyruvate; TCA cycle; oxidation of glucose to pyruvate; oxidative phosphorylation
glycolysis; oxidative phosphorylation; TCA cycle; oxidation of pyruvate.
glycolysis; reduction of pyruvate; TCA cycle; oxidative phosphorylation
oxidation of glucose to pyruvate; reduction of pyruvate; TCA cycle; oxidative phosphorylation
oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation

oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation

Oxygen gas (O2) is one of the strongest oxidizing agents known. The explanation for this is that _____. ( Concept 9.1)

oxygen gas contains a double bond
the oxygen atom is very electronegative
oxygen is so abundant in the atmosphere
oxygen acts as the final electron acceptor in cellular respiration
oxygen gas is composed of two atoms of oxygen

the oxygen atom is very electronegative

The function of cellular respiration is to _____. ( Concept 9.1)

extract usable energy from glucose
produce carbohydrates
extract CO2 from the atmosphere
reduce CO2
synthesize macromolecules from monomers

extract usable energy from glucose

During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is reduced as a result of the reaction? ( Concept 9.1)

glucose
oxygen
carbon dioxide
water
both glucose and carbon dioxide

oxygen

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 32 ATP from one glucose molecule. What happens to the rest of the energy in glucose? ( Concept 9.1)

It is used to make water from hydrogen ions and oxygen.
It is stored as fat.
It is converted to heat.
It is released as carbon dioxide and water
It is converted to starch.

It is converted to heat.

Which of the following statements is the best explanation of what happens to the temperature and carbon dioxide concentration during a one-hour class period in a classroom of 300 students if the heating and air conditioning is turned off and all doors are kept closed? ( Concept 9.1)

Temperature goes up and the level of carbon dioxide goes down. This is because cellular respiration is an exergonic process that is only about 38% efficient; the remaining energy is lost to the environment as heat. Also, carbon dioxide is being converted to organic molecules such as fats and sugars during cellular respiration.
Neither temperature nor carbon dioxide levels change because cellular respiration is 100% efficient and because carbon dioxide produced by cellular respiration is just as rapidly consumed by cellular respiration.
Temperature goes down and carbon dioxide levels remain constant. This is because cellular respiration, being an endergonic reaction, requires an input of heat energy from the environment to occur and because carbon dioxide is neither produced nor consumed by cellular respiration.
Temperature and the level of carbon dioxide rise as heat and carbon dioxide are by-products of cellular respiration.
Temperature goes up but carbon dioxide levels remain constant because heat is a by-product of cellular respiration but carbon dioxide is converted to sugar during cellular respiration.

Temperature and the level of carbon dioxide rise as heat and carbon dioxide are by-products of cellular respiration.

A small amount of ATP is made in glycolysis by which of the following processes? ( Concept 9.1)

transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation
attachment of a free inorganic phosphate (Pi) group to ADP to make ATP
transport of electrons through a series of carriers
harnessing energy from the sun
transfer of electrons and hydrogen atoms to NAD+

transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation

Where do the reactions of glycolysis occur in a eukaryotic cell? ( Concept 9.1)

the inner membrane of the mitochondrion
the matrix of the mitochondrion
the cytosol
across the inner membrane of the mitochondrion
in the intermembrane space of the mitochondrion

the cytosol

Which process is the one in which glucose is oxidized to generate two molecules of pyruvate, and in which ATP and NADH are produced? ( Concept 9.1)

chemiosmosis
the oxidation of pyruvate
fermentation
the citric acid cycle
None of the listed responses is correct.

None of the listed responses is correct.

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 _____. ( Concept 9.2)

human cells must also perform glycolysis; the drug might also poison them
bacteria are prokaryotes; they usually don’t need to perform glycolysis
glycolysis produces so little ATP that the drug will have little effect
glycolysis can occur without the action of enzymes
this step in the pathway of glycolysis can be skipped in bacteria, but not in humans

human cells must also perform glycolysis; the drug might also poison them

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? ( Concept 9.2)

There are no oxidation or reduction reactions in glycolysis to produce CO2.
The products of glycolysis contain the same total number of carbon atoms as in the starting material.
The initial steps of glycolysis require an input of energy in the form of ATP (two per glucose).
There is very little ATP produced in glycolysis.
Glucose contains more carbons than the number of carbons found in the pyruvate products that are produced by glycolysis.

The products of glycolysis contain the same total number of carbon atoms as in the starting material.

Of the following molecules in the glycolytic pathway (the process of glycolysis), the one with the most chemical energy is _____. ( Concept 9.2)

pyruvate
fructose-1,6-bisphosphate
glucose
fructose-6-phosphate
glyceraldehyde-3-phosphate

fructose-1,6-bisphosphate

Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes? ( Concept 9.3)

the citric acid cycle
oxidative phosphorylation
glycolysis
substrate-level phosphorylation
anabolic pathways

the citric acid cycle

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 _____. ( Concept 9.3)

NADH
carbon dioxide
water
oxygen gas
ATP

carbon dioxide

In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs? ( Concept 9.3)

Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH.
Pyruvate is reduced and decarboxylated, and the resulting electrons oxidize an NAD+ to an NADH
Pyruvate is oxidized and decarboxylated, and the resulting electrons are donated to NADH to produce NAD+.
Pyruvate is reduced to acetyl-coA, which involves the reduction of pyruvate, the addition of a carbon dioxide from the environment, and its reduction by NADH.
Pyruvate is ionized directly to acetyl-coA.

Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH.

Why is the citric acid cycle called a cycle? ( Concept 9.3)

NAD+ and FAD are recycled.
All of the carbon from glucose is cycled back into the atmosphere as carbon dioxide.
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.
NADH is cycled down the electron transport chain.
The acetyl CoA that enters the cycle is regenerated in the last step of the pathway.

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.

In the citric acid cycle, for each pyruvate that enters the cycle, one ATP, three NADH, and one FADH2 are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle? ( Concept 9.3)

about 38 ATP
four ATP, six NADH, two FADH2
two ATP, six NADH, two FADH2
three ATP, three NADH, one FADH2
one ATP, three NADH, one FADH2

two ATP, six NADH, two FADH2

Where do the reactions of the citric acid cycle occur in eukaryotic cells? ( Concept 9.3)

the intermembrane space of the mitochondrion
across the inner membrane of the mitochondrion
the matrix of the mitochondrion
the cristae of the mitochondrion
the cytosol

the matrix of the mitochondrion

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? ( Concept 9.3)

two
three
four
about 16 ATP
about 32 ATP

four

Which of the following represents the major (but not the only) energy accomplishment of the citric acid cycle? ( Concept 9.3)

formation of NADH and FADH2
utilization of O2
formation of ATP
completion of substrate-level phosphorylation
formation of CO2

formation of NADH and FADH2

After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of _____. ( Concept 9.3)

acetyl CoA
FADH2
NADH
CO2
ATP

NADH

Which of the following accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle? ( Concept 9.3)

release of CO2 and release of coenzyme A
formation of CO2 and synthesis of ATP
regeneration of NAD+
release of CO2 and synthesis of NADH
removal of coenzyme A

release of CO2 and synthesis of NADH

The energy given up by electrons as they move through the electron transport chain is used in which of the following processes? ( Concept 9.4)

the production of NADH and FADH2
the production of CO2
pumping H+ across a membrane
the oxidation of water
the breakdown of glucose

pumping H+ across a membrane

The ATP synthase in a human cell obtains energy for synthesizing ATP directly from which of the following processes? ( Concept 9.4)

the reduction of oxygen
the flow of H+ across the inner mitochondrial membrane through the ATP synthase enzyme
the movement of electrons through a series of carriers
the oxidation of glucose
the oxidation of NADH and FADH2

the flow of H+ across the inner mitochondrial membrane through the ATP synthase enzyme

When a poison such as cyanide blocks the electron transport chain, glycolysis and the citric acid cycle also eventually stop working. Which of the following is the best explanation for this? ( Concept 9.4)

NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.
A high level of NADH is present in the cell.
They run out of ADP.
Electrons are no longer available from the electron transport chain to power glycolysis and the citric acid cycle.
The uptake of oxygen stops because electron transport was inhibited.

NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.

Most of the electrons removed from glucose by cellular respiration are used for which of the following processes? ( Concept 9.4)

reducing NAD+ to NADH in glycolysis and the citric acid cycle
producing a proton gradient for ATP synthesis in the mitochondria
driving substrate-level phosphorylation in glycolysis
The first two choices are correct.
The second and third answers are correct.

The first two choices are correct.

Which part of the catabolism of glucose by cellular respiration requires molecular oxygen (O2) and produces CO2? ( Concept 9.4)

the combination of the citric acid cycle and electron transport
the electron transport chain
glycolysis
the citric acid cycle
the combination of glycolysis and the citric acid cycle

the combination of the citric acid cycle and electron transport

During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes? (Concept 9.4)

at the end of the citric acid cycle to regenerate citric acid
between glycolysis and the citric acid cycle to split a carbon from pyruvate, producing CO2
as a source of O2 in every reaction that produces CO2
at the end of glycolysis to oxidize pyruvate
at the end of the electron transport chain to accept electrons and form H2O

at the end of the electron transport chain to accept electrons and form H2O

Which of the following substances is/are involved in oxidative phosphorylation? ( Concept 9.4)

ADP
oxygen
ATP
None of the listed responses is correct.
The first three listed responses are involved in oxidative phosphorylation.

The first three listed responses are involved in oxidative phosphorylation.

Which of the following best describes the electron transport chain? ( Concept 9.4)

Electrons are passed from one carrier to another, releasing a little energy at each step.
Glucose is broken down to a three-carbon compound in preparation for the citric acid cycle.
Electrons are pumped across a membrane by active transport.
Acetyl CoA is fully oxidized to CO2.
Hydrogen atoms are added to CO2 to make an energy-rich compound.

Electrons are passed from one carrier to another, releasing a little energy at each step.

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? ( Concept 9.4)

ATP synthesis
glycolysis
electron transport
All of the listed responses are correct.
None of the listed responses is correct.

None of the listed responses is correct.

Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria? ( Concept 9.4)

electrons moving down the electron transport chain
ATP
an ATP-dependent proton pump
the components of the electron transport chain
the production of NADH

electrons moving down the electron transport chain

During respiration in eukaryotic cells, the electron transport chain is located in or on the _____. (Concept 9.4)

matrix of the mitochondrion
inner membrane of the mitochondrion
cytosol
intermembrane space of the mitochondrion
None of the listed responses is correct.

inner membrane of the mitochondrion

The overall efficiency of respiration (the percentage of the energy released that is saved in ATP) is approximately _____. ( Concept 9.4)

100%
2%
35%
0.5%
94%

35%

When solid tumors of animals reach a certain size, the center of the tumor begins to die. To prevent this, the tumor can recruit new blood vessels. What purpose does the recruitment of blood vessels to growing tumors serve? ( Concept 9.4)

The second and third explanations together represent the best answer.
It supplies oxygen so that aerobic cellular respiration can occur instead of fermentation.
The first and second explanations together represent the best answer.
It supplies a non-oxygen electron acceptor to cells so that the cells can respire anaerobically.
It supplies glucose to the rapidly dividing cells of the tumor.

The second and third explanations together represent the best answer.

Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step _____. ( Concept 9.5)

removes poisonous oxygen from the environment
enables the cell to recycle the reduced NADH to oxidized NAD+
prevents pyruvate from accumulating
extracts a bit more energy from glucose
enables the cell to make pyruvate into substances it can use

enables the cell to recycle the reduced NADH to oxidized NAD+

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? ( Concept 9.5)

oxygen
ATP
lactate
ADP
carbon dioxide

lactate

In glycolysis in the absence of oxygen, cells need a way to regenerate which compound? ( Concept 9.5)

NAD+
glucose
lactate
carbon dioxide
ethanol

NAD+

Muscle tissues make lactate from pyruvate to do which of the following? ( Concept 9.5)

get rid of pyruvate produced by glycolysis
utilize the energy in pyruvate
speed up the rate of glycolysis
regenerate NAD+
produce additional CO2

regenerate NAD+

In brewing beer, maltose (a disaccharide of glucose) is _____. ( Concept 9.5)

a substitute for pyruvate that cannot be made in yeast
the substrate for alcoholic fermentation
a sweetener
the substrate for aerobic respiration
one of the enzymes for alcoholic fermentation

the substrate for alcoholic fermentation

If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result? ( Concept 9.5)

The muscle cells will have more trouble making enough ATP to meet their energy requirements.
The cells will not be able to carry out oxidative phosphorylation.
The cells will consume glucose at an increased rate.
Only the first two answers are correct.
The first three answers are correct.

The first three answers are correct.

Of the metabolic pathways listed below, which is the only pathway found in all organisms? ( Concept 9.5)

the electron transport chain
fermentation
the citric acid cycle
cellular respiration
glycolysis

glycolysis

When protein molecules are used as fuel for cellular respiration, _____ are produced as waste. (Concept 9.6)

fatty acids
molecules of lactate
ethanol and CO2
amino groups
sugar molecules

amino groups

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? ( Concept 9.6)

Fats are closely related to lipid molecules, the basic building blocks of cellular membranes.
Fats are better electron donors to oxygen than are sugars.
Fats are produced when cells take in more food than they need.
Fats are less soluble in water than sugars.
Fats do not form true macromolecules as sugars do.

Fats are better electron donors to oxygen than are sugars.

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? ( Concept 9.6)

Less ATP will be produced by the cell.
Less CO2 will be produced by the cell.
The four-carbon compound that combines with acetyl CoA will have to be made by some other process.
The first two answers are correct.
The first three answers are correct.

The first three answers are correct.