chapter 9: cellular respiration
A typical eukaryotic cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen to an individual when they exhaust their ATP supply?
Catabolic processes will be activated to generate additional ATP.
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
glycolysis
If the proteins of the electron transport chain were labeled with a fluorescent tag, the fluorescence observed by microscopy will be localized to which of the following regions of the mitochondria?
inner membrane
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
ionic
The final electron acceptor of cellular respiration is _____.
oxygen
When a cell is deprived of oxygen, which of the following processes will be inhibited first?
the electron transport chain
For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle.
6
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.)
Both electron transport and ATP synthesis would stop.
Select the correct statement about cellular respiration
Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level
Which of the following molecules is the lowest-energy donor of electrons to the electron transport chain?
FADH2
Which of these is NOT a product of glycolysis?
FADH2
Which of the following statements best describes the primary role played by oxygen in cellular respiration?
It serves as the final acceptor for electrons from the electron transport chain
The standard free energy for the complete oxidation of glucose to CO2 and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced?
Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom?
NAD+ becomes reduced.
Which of the following is the most likely effect on the rates of ATP and CO2 production if yeast cells growing in minimal medium lacking glucose are provided with supplemental acetyl-CoA?
The rates of ATP production and carbon dioxide production would both increase.
Which of the following is true for all exergonic reactions?
The reaction proceeds with a net release of free energy.
Which one of the following statements about the redox reactions of the electron transport chain is correct?
The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane.
If a cell produces on average 30 ATP molecules for each molecule of glucose that is completely oxidized to carbon dioxide and water, how many ATP molecules on average can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
12.5
For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.
2
In glycolysis there is a net gain of _____ ATP.
2 It takes 2 ATP to produce 4 ATP.
Which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle?
3 ATP, 6 CO2, 9 NADH, and 3 FADH2
Which of the following is one of the molecules formed by the removal of a carboxyl group (as CO2) from a molecule of pyruvate?
acetyl CoA
Which of these is NOT a product of the citric acid cycle?
acetyl CoA
Which step of the cellular respiration pathway can take place in the absence of oxygen?
glycolysis
When a glucose molecule loses a hydrogen atom in an oxidation-reduction reaction, the glucose molecule is ________.
oxidize
In mitochondria, exergonic redox reactions
provide the energy that establishes the proton gradient
Glycolysis results in the net production of which of the following sets of molecules per glucose molecule?
2 NADH, 2 pyruvate, and 2 ATP
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
30-32
For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)?
4
In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules?
ATP, CO2, and ethanol
New biosensors, applied like a temporary tattoo to the skin, can alert endurance athletes that they are about to "hit the wall" and will find it difficult to continue exercising. These biosensors monitor lactate present in sweat during strenuous exercise. Which of the statements below best explains the use of lactate as an indicator of exercise capacity?
During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
Which stage of glucose metabolism produces the most ATP?
Electron transport and chemiosmosis
If a mitochondrion ran out of molecular oxygen (O2), predict which of the following situations would occur in its electron transport chain.
FMN prosthetic groups would remain reduced and NADH would have nowhere to donate electrons.
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
H+ concentration gradient across the membrane holding ATPATP synthase
Which of the following statements best supports the claim that glycolysis is likely one of the first metabolic pathways to have evolved?
It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
Which of the following statements best describes how a reducing agent in is chemically altered in a biological redox reaction?
It loses a hydrogen atom and loses potential energy
Which of the following statements describing the process of glycolysis is correct?
It represents the first stage in the chemical oxidation of glucose by a cell.
In muscle cells, fermentation produces _____.
lactate and NAD+
Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?
mitochondrial intermembrane space
Inhibition of which of the following metabolic pathways would result in decreased rates of CO2 production?
oxidation of pyruvate to acetyl CoA and the citric acid cycle
In cellular respiration, most ATP molecules are produced by _____.
oxidative phosphorylation
In liver cells, the inner mitochondrial membranes contain about five times the surface area of the outer mitochondrial membranes, which allows for increased rates of which process below?
oxidative phosphorylation
Which of the following processes is driven by chemiosmosis?
oxidative phosphorylation
How will a healthy individual's ATP production change during an eight-hour fast?
The individual's ATP production will not change significantly
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location than the active site. This is an example of which of the following?
allosteric regulation
Inhibition of which of the following processes would reduce or eliminate generation of a proton-motive force in mitochondria?
pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space
What is the oxidizing agent in the following reaction? Pyruvate+NADH+H+→Lactate+NAD+
pyruvate
In fermentation _____ is reduced and _____ is oxidized.
pyruvate ... NADH
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
pyruvate, ATP, and NADH
When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________.
reduced, and energy is released
A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. In which of the following forms did the lost fat most likely leave the body?
released as CO2 and H2O
Catabolism of fatty acids produces two-carbon molecules that are converted to acetyl CoA. The acetyl CoA molecules will most likely be metabolized in aerobic cellular respiration by which of the following mechanisms?
directly entering the citric acid cycle
Beta oxidation generates substrates for cellular respiration through catabolism of which of the following molecules?
fatty acids
Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?
fermentation
In chemiosmosis, the most direct source of energy used to convert ADP + Pi to ATP is energy released ________.
from movement of protons through ATP synthase, down their electrochemical gradient
In the process of cellular respiration, what is consumed and what is produced?
glucose is consumed and carbon dioxide is produced
Which of the following sequences describes the path by which electrons move from high-energy to lower-energy molecules in aerobic respiration?
glucose → NADH → electron transport chain → oxygen
Which of the following metabolic processes normally occurs in most cells regardless of oxygen (O2) availability?
glycolysis
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?
glycolysis and fermentation
Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation?
in all cells, with or without light
In which reactions of cellular respiration does substrate-level phosphorylation occur?
in both glycolysis and the citric acid cycle
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 happens to most of the energy that the cell obtains from the oxidation of glucose?
it is stored in NADH and FADH2
Which of the following events takes place in the electron transport chain?
the harnessing of energy from redox reactions to generate a proton gradient
Which of the following statements best summarizes ATP use and production in the catabolism of each glucose molecule in glycolysis?
two molecules of ATP are used, and four molecules of ATP are produced
The electrons stripped from glucose in cellular respiration ultimately end up in which compound?
water
Which of the following statements best describes the electron transport chain?
It consists of a series of redox reactions.
Which of these enters the citric acid cycle?
Acetyl CoA
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 that a small amount of energy is released with the transfer of an electron between each pair of intermediates
Most CO2 from catabolism is released during
citric acid cycle
Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose?
citric acid cycle
If glucose is the sole energy source for cellular respiration in an animal, what proportion of the carbon dioxide exhaled is derived from oxidation of pyruvate to acetyl CoA?
1/3
How many NADH are produced by glycolysis?
two
Which of the following statements is not true of most cellular redox reactions?
A hydrogen atom is transferred to the atom that loses an electron.
In glycolysis, what starts the process of glucose oxidation?
ATP
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels of which of the following molecules?
ATP and citrate
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?
Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.
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?
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.
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.
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.
During electron transport, energy from _____ is used to pump hydrogen ions into the _____.
NADH and FADH2 ... intermembrane space
Which of the following statements about the electron transport chain is true?
NADH and FADH2 donate their electrons to the chain
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
O2
If pyruvate oxidation is blocked, what is the most likely effect on the levels of oxaloacetate and citrate in the citric acid cycle shown in the accompanying figure?
Oxaloacetate will accumulate and citrate will decrease.
Which of the following statements is true of the bonds in a water molecule?
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
Identify all correct statements about the basic function of fermentation
The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis
Which of the following statements about the chemiosmotic synthesis of ATP is correct?
The chemiosmotic synthesis of ATP requires that electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.
Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration?
The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP
Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal to form small vesicles that contain the intermembrane space. These vesicles can transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements best describes what will happen to the vesicles when NADH is added?
The inside of the vesicles will become acidic.
Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal "inside out" to form small vesicles. The fact that these vesicles can transfer electrons from NADH to oxygen and synthesize ATP suggests that which of the following components must be present?
all of the electron transport system and ATP synthase
Which of the following types of metabolic poison would most directly interfere with glycolysis?
an agent that closely mimics the structure of glucose but is not metabolized
Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?
carbon dioxide
The synthesis of ATP by oxidative phosphorylation is an example of which of the following processes?
coupling of an endergonic reaction to an exergonic reaction
Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP?
glucose
Yeast cells with defective mitochondria that are incapable of performing cellular respiration will be able to survive by using which of the following molecules for energy?
glucose
The proximate (immediate) source of energy for oxidative phosphorylation is _____.
kinetic energy that is released as hydrogen ions diffuse down their concentration gradient
A covalent bond is likely to be polar when
one of the atoms sharing electrons is much more electronegative than the other atom
Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?
oxidation of NADH to NAD+
In the following reaction which molecule functions as the oxidizing agent? Pyruvate + NADH + H+ → Lactate + NAD+
pyruvate
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
In the citric acid cycle, ATP molecules are produced by _____.
substrate-level phosphorylation
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 removed from these processes to serve as building blocks for other complex molecules
In mitochondrial electron transport, what is the direct role of O2?
to function as the final electron acceptor in the electron transport chain
Which of the following is the most important result of the process of cellular respiration in biological systems?
transforming the energy in glucose and related molecules into a chemical form that cells can use for work
True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.
true
True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.
true
Substrate-level phosphorylation accounts for approximately what percent of the ATP formed by the reactions of glycolysis?
100%
In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis?
2 ATP
A 3-year old dog has never been able to tolerate much physical activity. A veterinarian discovers that the dog's mitochondria can use only fatty acids and amino acids for cellular respiration, and its muscle cells produce elevated levels of lactate. Which of the following statements best explains the dog's condition?
Its cells cannot transport pyruvate from the cytosol into the mitochondria.
Which of the following statements best describes a characteristic of NAD+?
NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle.
Which of the following statements about the citric acid cycle is correct?
The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.
When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?
The pH of the matrix increases
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Dogs affected with this disorder most likely display which of the following symptoms?
They are lethargic and readily tire from exercise.
Which of the following statements best explains why carbohydrates and fats may be considered high-energy foods?
They contain many electrons associated with hydrogen atoms.
What types of cells carry out ATP synthesis by chemiosmosis?
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
