Chapter 7 (test 2)
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the electron transport chain?
0%
Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in aerobic cellular respiration?
60-64
Why is the citric acid cycle called a cycle?
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.
During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes?
at the end of the electron transport chain to accept electrons and form H2O
Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria? the components of the electron transport chain the production of NADH electrons moving down the electron transport chain an ATP-dependent proton pump ATP
electrons moving down the electron transport chain
Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step __________.
enables the cell to recycle the reduced NADH to oxidized NAD+
Which metabolic pathway is common to both cellular respiration and fermentation?
glycolysis
The function of cellular respiration is to __________.
harvesting usable energy from glucose
During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is reduced as a result of the reaction?
oxygen
How many NADH are produced by glycolysis?
2
In glycolysis there is a net gain of _____ ATP.
2
In glycolysis, what starts the process of glucose oxidation?
ATP
In a mitochondrion, if the matrix ATP concentration is high and the intermembrane space proton concentration is too low to generate sufficient proton-motive force, then
ATP synthase will hydrolyze ATP and pump protons into the intermembrane space.
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.
Why is glycolysis described as having an energy investment phase and an energy payoff phase?
Early steps consume energy from ATP, and later steps store an increased amount of energy in ATP and NADH.
Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?
Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).
Which of the following best describes the electron transport chain? Electrons are passed from one carrier to another, releasing a little energy at each step. Acetyl CoA is fully oxidized to CO2. Electrons are pumped across a membrane by active transport. Glucose is broken down to a three-carbon compound in preparation for the citric acid cycle. 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.
Which of these is NOT a product of glycolysis? NADH pyruvate FADH2 ATP
FADH2
In the combined processes of glycolysis and cellular respiration, what is consumed, and what is produced?
Glucose is consumed, and carbon dioxide is produced.
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?
It is converted to heat.
In glycolysis in the absence of oxygen, cells need a way to regenerate which compound?
NAD+
Which of the following statements about NAD+ is true? NAD+ is the source of electrons used in oxidative phosphorylation. NAD+ is oxidized by the action of dehydrogenase enzymes. NAD+ has more chemical energy than NADH. NAD+ is reduced to NADH during glycolysis.
NAD+ is reduced to NADH during glycolysis.
After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of __________.
NADH
In addition to ATP, what are the end products of glycolysis?
NADH and pyruvate
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? ATP synthesis electron transport glycolysis All of the listed responses are correct. None of the listed responses is correct.
None of the listed responses is correct.
Which process is the one in which glucose is oxidized to generate two molecules of pyruvate, and in which ATP and NADH are produced? fermentation the citric acid cycle chemiosmosis the oxidation of pyruvate None of the listed responses is correct.
None of the listed responses is correct.
In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?
Pyruvate is oxidized and decarboxylated, and the removed electrons are used to reduce an NAD+ to an NADH.
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? 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 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.
Which of the following statements about the chemiosmotic synthesis of ATP is correct? The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. Oxygen participates directly in the reaction that makes ATP from ADP and P. The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. The chemiosmotic synthesis of ATP occurs only in eukaryotic cells because it occurs in mitochondria. Chemiosmotic ATP synthesis requires oxygen.
The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.
If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result? 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.
Which of the following substances is/are involved in oxidative phosphorylation? 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.
Most of the electrons removed from glucose by cellular respiration are used for which of the following processes? 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 statement about the citric acid cycle is correct? The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle. The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain. The oxidation of compounds by the citric acid cycle requires molecular oxygen. The citric acid cycle oxidizes glucose to carbon dioxide.
The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.
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? The initial steps of glycolysis require an input of energy in the form of ATP (two per glucose). 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. There is very little ATP produced in glycolysis. 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.
Which of these enters the citric acid cycle? glucose pyruvate G3P acetyl CoA NADH + H+
acetyl CoA
Which of these is NOT a product of the citric acid cycle? NADH + H+ acetyl CoA ATP CO2 FADH2
acetyl CoA
Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate? acetyl CoA citrate lactate oxaloacetate glyceraldehyde-3-phosphate
acetyl CoA
When protein molecules are used as fuel for cellular respiration, __________ are produced as waste.
amino groups
During intense exercise, as skeletal muscle cells switch to fermentation, the human body will increase its catabolism of
carbohydrates only.
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 __________.
carbon dioxide
Which of the following represents the major (but not the only) energy accomplishment of the citric acid cycle? formation of CO2 utilization of O2 completion of substrate-level phosphorylation formation of NADH and FADH2 formation of ATP
formation of NADH and FADH2
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?
four
In the overall process of glycolysis and cellular respiration, __________ is oxidized and __________ is reduced.
glucose ... oxygen
Which of the following indicates a primary path by which electrons travel downhill energetically during aerobic respiration? glucose → NADH → electron transport chain → oxygen glucose → pyruvate → acetyl CoA → ATP → oxygen glucose → glycolysis → electron transport chain → NADH → ATP glucose → citric acid cycle → ATP → NAD+ glucose → glycolysis → citric acid cycle → NADH → ATP
glucose → NADH → electron transport chain → oxygen
The complete oxidation of glucose in aerobic respiration occurs through which of the following sequence of metabolic reactions? glucose → glycolysis → citric acid cycle → pyruvate oxidation → electron transport chain glucose → glycolysis → pyruvate oxidation → citric acid cycle → electron transport chain glucose → citric acid cycle → glycolysis → pyruvate oxidation → electron transport chain glucose → pyruvate oxidation → citric acid cycle → glycolysis → electron transport chain glucose → pyruvate oxidation → glycolysis → electron transport chain → citric acid cycle
glucose → glycolysis → pyruvate oxidation → citric acid cycle → electron transport chain
Of the metabolic pathways listed below, which is the only pathway found in all organisms?
glycolysis
Which of the following occur(s) in the cytosol of a eukaryotic cell? oxidation of pyruvate to acetyl CoA fermentation and chemiosmosis oxidative phosphorylation glycolysis and fermentation citric acid cycle
glycolysis and fermentation
Where in mitochondria is the enzyme ATP synthase localized?
inner membrane
During respiration in eukaryotic cells, the electron transport chain is located in or on the __________.
inner membrane of the mitochondrion
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? ADP carbon dioxide ATP lactate oxygen
lactate
In muscle cells, fermentation produces _____.
lactate and NAD+
A molecule becomes more oxidized when it __________.
loses an electron
In an oxidation-reduction reaction, the reducing agent
loses electrons and loses potential energy.
Where are the proteins of the electron transport chain located?
mitochondrial inner membrane
The complete reactions of cellular respiration in the presence of oxygen (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy) result in which of the following? reduction of CO2 and oxidation of O2 oxidation of C6H12O6 and reduction of O2 oxidation of O2 and reduction of H2O reduction of C6H12O6 and oxidation of CO2
oxidation of C6H12O6 and reduction of O2
Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration? oxidation of glucose to pyruvate; reduction of pyruvate; citric acid cycle; oxidative phosphorylation oxidation of pyruvate; citric acid cycle; oxidation of glucose to pyruvate; oxidative phosphorylation glycolysis; reduction of pyruvate; citric acid cycle; oxidative phosphorylation glycolysis; oxidative phosphorylation; citric acid cycle; oxidation of pyruvate. 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
Most of the ATP produced in cellular respiration comes from which of the following processes?
oxidative phosphorylation
One primary function of both alcohol fermentation and lactic acid fermentation is to
oxidize NADH to NAD+
In fermentation _____ is reduced and _____ is oxidized.
pyruvate ... NADH
In alcohol fermentation, NAD+ is regenerated from NADH by
reduction of acetaldehyde to ethanol.
Muscle tissues make lactate from pyruvate to do which of the following? regenerate NAD+ utilize the energy in pyruvate get rid of pyruvate produced by glycolysis speed up the rate of glycolysis produce additional CO2
regenerate NAD+
The primary role of oxygen in cellular respiration is to
serve as an acceptor for electrons and hydrogen, forming water.
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
In the citric acid cycle, ATP molecules are produced by _____.
substrate-level phosphorylation
Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes? oxidative phosphorylation glycolysis the citric acid cycle anabolic pathways substrate-level phosphorylation
the citric acid cycle
Which part of the catabolism of glucose by cellular respiration requires molecular oxygen (O2) and produces CO2?
the combination of the citric acid cycle and electron transport
Where do the reactions of glycolysis occur in a eukaryotic cell?
the cytosol
Which metabolic pathway generates a proton gradient?
the electron transport chain
Where do the reactions of the citric acid cycle occur in eukaryotic cells?
the matrix of the mitochondrion
Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration? breaking down ATP so that ADP and P can be reused 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 catabolism of sugars and related compounds 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
The electrons stripped from glucose in cellular respiration end up in which compound?
water
