Chapter 7 test 2
Which of these is NOT a product of glycolysis? FADH2 ATP NADH pyruvate
FADH2
Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? Fermentation Krebs cycle Electron transport chain Glycolysis
Fermentation
How many NADH are produced by glycolysis? 1 5 3 4 2
2
In glycolysis there is a net gain of _____ ATP. 1 5 2 3 4
2
Starting with one molecule of glucose, the energy-containing products of glycolysis are 2 NADH, 2 pyruvate, and 2 ATP. 2 FADH2, 2 pyruvate, and 4 ATP. 6 CO2, 2 pyruvate, and 2 ATP. 6 CO2, 2 pyruvate, and 30 ATP. 2 NAD+, 2 pyruvate, and 2 ATP.
2 NADH, 2 pyruvate, and 2 ATP.
Which of the following statements is not true of most cellular redox reactions? The electron acceptor is reduced. The reactant that is oxidized loses electrons. A hydrogen atom is transferred to the atom that loses an electron. Changes in potential energy can be released as heat.
A hydrogen atom is transferred to the atom that loses an electron.
In glycolysis, what starts the process of glucose oxidation? hexokinase NADPH ATP FADH2 ADP
ATP
The rate of cellular respiration is regulated by its major product, ATP, via feedback inhibition. As the diagram shows, high levels of ATP inhibit phosphofructokinase (PFK), an early enzyme in glycolysis. As a result, the rate of cellular respiration, and thus ATP production, decreases. Feedback inhibition enables cells to adjust their rate of cellular respiration to match their demand for ATP. Simple diagram showing glycolosis, the citric acid cycle, and oxidative phophorylation. High levels of ATP produced by these processes inhibits phosphofructokinase, an early enzyme in glycolosis. Suppose that a cell's demand for ATP suddenly exceeds its supply of ATP from cellular respiration. Which statement correctly describes how this increased demand would lead to an increased rate of ATP production? ATP levels would rise at first, increasing the inhibition of PFK and increasing the rate of ATP production. ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production. ATP levels would fall at first, increasing the inhibition of PFK and increasing the rate of ATP production. ATP levels would rise at first, decreasing the inhibition of PFK and increasing the rate of ATP production.
ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of ATP, CO2, and ethanol (ethyl alcohol). ATP, pyruvate, and oxygen. ATP, CO2, and lactate. ATP, pyruvate, and acetyl CoA. ATP, NADH, and pyruvate.
ATP, CO2, and ethanol (ethyl alcohol).
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other? Proton and electron. Ionic and covalent. Polar and nonpolar. Anion and cation.
Anion and cation.
How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.) Neither electron transport nor ATP synthesis would be affected. Electron transport would stop but ATP synthesis would be unaffected. Electron transport would be unaffected but ATP synthesis would stop. Both electron transport and ATP synthesis would stop.
Both electron transport and ATP synthesis would stop.
Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy CO2 is reduced and O2 is oxidized. C6H12O6 is reduced and CO2 is oxidized. C6H12O6 is oxidized and O2 is reduced. O2 is oxidized and H2O is reduced. O2 is reduced and CO2 is oxidized.
C6H12O6 is oxidized and O2 is reduced.
Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? Water NADH Carbon dioxide ATP
Carbon dioxide
Select the correct statement about cellular respiration. Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis. Animals carry out cellular respiration whereas plants carry out photosynthesis. Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.
Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.
Which stage of glucose metabolism produces the most ATP? Electron transport and chemiosmosis Krebs cycle Glycolysis Fermentation of pyruvate to lactate
Electron transport and chemiosmosis
Which term describes the degree to which an element attracts electrons? Oxidation. Reduction. Polarity. Electronegativity.
Electronegativity.
NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule. Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2? There is more NADH than FADH2 made for every glucose that enters cellular respiration. It takes more energy to make ATP from ADP and Pi using FADH2 than using NADH. FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle. Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2.
Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.
Which molecule is metabolized in a cell to produce energy for performing work? ADP ATP Phosphate Glucose
Glucose
Under anaerobic conditions (a lack of oxygen), glycolysis continues in most cells despite the fact that oxidative phosphorylation stops, and its production of NAD+ (which is needed as an input to glycolysis) also stops. The diagram illustrates the process of fermentation, which is used by many cells in the absence of oxygen. In fermentation, the NADH produced by glycolysis is used to reduce the pyruvate produced by glycolysis to either lactate or ethanol. Fermentation results in a net production of 2 ATP per glucose molecule. Diagram showing the process of fermentation During strenuous exercise, anaerobic conditions can result if the cardiovascular system cannot supply oxygen fast enough to meet the demands of muscle cells. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions. What would happen to the cell's rate of glucose utilization? Glucose utilization would increase a lot. Glucose utilization would increase a little. Glucose utilization would remain the same. Glucose utilization would decrease a little. Glucose utilization would decrease a lot.
Glucose utilization would increase a lot.
Which step of the cellular respiration pathway can take place in the absence of oxygen? Fermentation Krebs cycle Glycolysis Electron transport chain
Glycolysis
Which statement best supports the hypothesis that glycolysis is an ancient metabolic pathway that originated before the last universal common ancestor of life on Earth? Glycolysis neither uses nor needs O2. Glycolysis is found in all eukaryotic cells. Ancient prokaryotic cells, the most primitive of cells, made extensive use of glycolysis long before oxygen was present in Earth's atmosphere. The enzymes of glycolysis are found in the cytosol rather than in a membrane-enclosed organelle. Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya.
Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya.
Gaseous hydrogen burns in the presence of oxygen to form water: 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed? Hydrogen, nonpolar. Hydrogen, polar. Oxygen, nonpolar. Oxygen, polar.
Hydrogen, polar.
Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. Which of these statements is the correct explanation for this observation? Oxygen is an input to acetyl CoA formation. In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration. ATP is needed to convert pyruvate to acetyl CoA. Without oxygen, no ATP can be made in oxidative phosphorylation. Oxygen is required to convert glucose to pyruvate in glycolysis. Without oxygen, no pyruvate can be made.
In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration.
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? Nonpolar covalent. Ionic. Redox. Polar covalent.
Ionic.
Why is the citric acid cycle a cyclic pathway rather than a linear pathway? In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction. Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct. More ATP is produced per CO2 released in cyclic processes than in linear processes. It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA. Redox reactions that simultaneously produce CO2 and NADH occur only in cyclic processes. Cyclic processes, such as the citric acid cycle, require a different mechanism of ATP synthesis than linear processes, such as glycolysis.
It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.
A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose? It is stored in NADH and FADH2 It is stored in the carbon dioxide and water molecules released by these processes. It is stored in the ATP that was formed by glycolysis and the citric acid cycle. It was lost as heat. It is stored in pyruvate.
It is stored in NADH and FADH2
Which of the following describes the process of glycolysis? Glycolysis produces 30 ATP from each molecule of glucose. It converts one glucose molecule to two molecules of pyruvate and carbon dioxide. Glycolysis occurs in the mitochondria. It represents the first stage in the chemical oxidation of glucose by a cell. It requires ATP and NADH.
It represents the first stage in the chemical oxidation of glucose by a cell.
Why is glycolysis described as having an investment phase and a payoff phase? It attaches and detaches phosphate groups. It shifts molecules from cytosol to mitochondrion. It both splits molecules and assembles molecules. It uses glucose and generates pyruvate. It uses stored ATP and then forms a net increase in ATP.
It uses stored ATP and then forms a net increase in ATP.
Which of the following statements about the electron transport chain is true? Electrons gain energy as they move down the chain. NADH and FADH2 donate their electrons to the chain. The electron transport chain is the first step in cellular respiration. Water is the last electron acceptor.
NADH and FADH2 donate their electrons to the chain.
In addition to ATP, what are the end products of glycolysis? CO2 and H2O NADH and pyruvate H2O, FADH2, and citrate CO2 and NADH CO2 and pyruvate
NADH and pyruvate
Which of the following statements is true of the bonds in a water molecule? Oxygen acts as the electron acceptor and is oxidized. Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero. The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1.
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain? The advantage of an electron transport chain is the production of a large number of reduced, high-energy intermediates. The advantage of the respiratory electron transport chain is that oxygen is the final electron acceptor. The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates.
The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates.
Identify all correct statements about the basic function of fermentation. Select all that apply. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis. The basic function of fermentation is the production of ethyl alcohol or lactic acid.
The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis.
In most cells, not all of the carbon compounds that participate in glycolysis and the citric acid cycle are converted to carbon dioxide by cellular respiration. What happens to the carbon in these compounds that does not end up as CO2? They are used to make NADH. They are used to make ATP from NADH. The carbon compounds are removed from these processes to serve as building blocks for other complex molecules. These carbon compounds are used to convert ADP to ATP via chemiosmosis. They are converted to heat energy.
The carbon compounds are removed from these processes to serve as building blocks for other complex molecules.
Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration? The function of the bonding of acetic acid to the carrier molecule CoA to form acetyl CoA is the reduction of glucose to acetyl CoA. The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP. The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2.
The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.
Why are carbohydrates and fats considered high-energy foods? They can have very long carbon skeletons. They are easily reduced. They have a lot of electrons associated with hydrogen. They have a lot of oxygen atoms. They have no nitrogen in their makeup.
They have a lot of electrons associated with hydrogen.
True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups. True False
True
True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria. True False
True
The oxygen consumed during cellular respiration is involved directly in which process or event? the oxidation of pyruvate to acetyl CoA the phosphorylation of ADP to form ATP glycolysis the citric acid cycle accepting electrons at the end of the electron transport chain
accepting electrons at the end of the electron transport chain
Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle? succinyl CoA pyruvate acetyl CoA malate or fumarate α-ketoglutarate
acetyl CoA
Which of these enters the citric acid cycle? G3P glucose pyruvate NADH + H+ acetyl CoA
acetyl CoA
Which of these is NOT a product of the citric acid cycle? ATP CO2 FADH2 NADH + H+ acetyl CoA
acetyl CoA
What is the purpose of beta oxidation in respiration? oxidation of pyruvate oxidation of glucose feedback regulation breakdown of fatty acids control of ATP accumulation
breakdown of fatty acids
What molecules belong in spaces E and F? carbon dioxide and water glucose, water, carbon dioxide, and oxygen carbon dioxide and oxygen oxygen and water glucose and oxygen
carbon dioxide and water
What is the term for metabolic pathways that release stored energy by breaking down complex molecules? catabolic pathways anabolic pathways fermentation pathways bioenergetic pathways thermodynamic pathways
catabolic pathways
Inside an active mitochondrion, most electrons follow which pathway? pyruvate → citric acid cycle → ATP → NADH → oxygen citric acid cycle → FADH2 → electron transport chain ATP electron transport chain → citric acid cycle → ATP oxygen citric acid cycle → NADH → electron transport chain oxygen glycolysis → NADH → oxidative phosphorylation ATP → oxygen
citric acid cycle → NADH → electron transport chain oxygen
Where does glycolysis take place in eukaryotic cells? mitochondrial matrix mitochondrial inner membrane mitochondrial intermembrane space mitochondrial outer membrane cytosol
cytosol
In chemiosmosis, what is the most direct source of energy that is used to convert ADP + i to ATP? energy released from dehydration synthesis reactions energy released from movement of protons through ATP synthase, down their electrochemical gradient No external source of energy is required because the reaction is exergonic. energy released as electrons flow through the electron transport system energy released from substrate-level phosphorylation
energy released from movement of protons through ATP synthase, down their electrochemical gradient
What molecules belong in space A and B? carbon dioxide and oxygen glucose and carbon dioxide glucose and oxygen carbon dioxide and water oxygen and water
glucose and oxygen
What process occurs in Box A? electron transport electron transport and oxidative phosphorylation the citric acid cycle oxidative phosphorylation glycolysis
glycolysis
Which metabolic pathway is common to both cellular respiration and fermentation? chemiosmosis the citric acid cycle oxidative phosphorylation the oxidation of pyruvate to acetyl CoA glycolysis
glycolysis
Which of the following normally occurs regardless of whether or not oxygen (O2) is present? oxidative phosphorylation (chemiosmosis) glycolysis fermentation oxidation of pyruvate to acetyl CoA citric acid cycle
glycolysis
Even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. When and where will this occur? in photosynthesizing cells in the light and in other tissues in the dark in photosynthetic cells in the light, while photosynthesis occurs concurrently in all cells all the time in nonphotosynthesizing cells only in cells that are storing glucose only
in all cells all the time
In muscle cells, fermentation produces _____. carbon dioxide, ethanol, NADH, and ATP lactate, NADH, and ATP lactate and NAD+ carbon dioxide, ethanol, and NAD+ pyruvate
lactate and NAD+
Where are the proteins of the electron transport chain located? mitochondrial outer membrane mitochondrial inner membrane mitochondrial matrix cytosol mitochondrial intermembrane space
mitochondrial inner membrane
What organelle is indicated by the letter C? chloroplast peroxisome mitochondrion lysosome Golgi apparatus
mitochondrion
Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water? citric acid cycle oxidation of pyruvate to acetyl CoA glycolysis fermentation oxidative phosphorylation (chemiosmosis)
oxidative phosphorylation (chemiosmosis)
One function of both alcohol fermentation and lactic acid fermentation is to reduce NAD+ to NADH. reduce FADH2 to FAD+. oxidize NADH to NAD+. reduce FAD+ to FADH2. do none of the above.
oxidize NADH to NAD+.
What molecule is indicated by the letter D? pyruvate ATP water glucose oxygen
oxygen
What process occurs in structure H? photosynthesis ribosome synthesis protein synthesis cellular respiration intracellular digestion
photosynthesis
In fermentation _____ is reduced and _____ is oxidized. lactate ... ethanol NAD+ ... pyruvate lactate ... NADH NADH ... lactate pyruvate ... NADH
pyruvate ... NADH
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions? CO2 only ATP only O2 only ATP and NADH only NADH only pyruvate, ATP, and NADH pyruvate and ATP only
pyruvate, ATP, and NADH
When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes hydrolyzed. dehydrogenated. reduced. oxidized. redoxed.
reduced.
In glycolysis, ATP molecules are produced by _____. cellular respiration oxidative phosphorylation photophosphorylation substrate-level phosphorylation photosynthesis
substrate-level phosphorylation
In the citric acid cycle, ATP molecules are produced by _____. cellular respiration photosynthesis oxidative phosphorylation photophosphorylation substrate-level phosphorylation
substrate-level phosphorylation
Most CO2 from catabolism is released during __________. electron transport glycolysis the citric acid cycle lactate fermentation oxidative phosphorylation
the citric acid cycle
What process occurs within Box B? photophosphorylation glycolysis electron transport the citric acid cycle oxidative phosphorylation
the citric acid cycle
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the formation of ATP. the lowering of pH in the mitochondrial matrix. the reduction of NAD+. the creation of a proton-motive force. the restoration of the Na+/K+ balance across the membrane.
the creation of a proton-motive force.
What is proton-motive force? the force provided by a transmembrane hydrogen ion gradient the force that moves hydrogen to NAD+ the force that moves hydrogen into the mitochondrion the force that moves hydrogen into the intermembrane space the force required to remove an electron from hydrogen
the force provided by a transmembrane hydrogen ion gradient
In mitochondrial electron transport, what is the direct role of O2? to oxidize NADH and FADH2 from glycolysis, acetyl CoA formation, and the citric acid cycle to function as the final electron acceptor in the electron transport chain to provide the driving force for the synthesis of ATP from ADP and PiHow would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.) Neither electron transport nor ATP synthesis would be affected. Electron transport would stop but ATP synthesis would be unaffected. Electron transport would be unaffected but ATP synthesis would stop. Both electron transport and ATP synthesis would stop. to provide the driving force for the production of a proton gradient
to function as the final electron acceptor in the electron transport chain
Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration? catabolism of sugars and related compounds transforming the energy in glucose and related molecules in a chemical form that cells can use for work the breakdown of glucose to carbon dioxide and water breaking down ATP, so that ADP and P can be reused producing complex molecules from chemical building blocks
transforming the energy in glucose and related molecules in a chemical form that cells can use for work
In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis? up to 30 ATP two ATP none, because in the absence of oxygen, no ATP can be made four ATP none, because all of the available energy remains in either lactate or ethanol
two ATP
The electrons stripped from glucose in cellular respiration end up in which compound? water oxygen carbon dioxide ATP NADH
water
