CH 09 HW
Which of the following metabolic processes normally occurs in yeast cells regardless of oxygen (O2) availability?
glycolysis
What process occurs in Box A? What process occurs within Box B? What molecule is indicated by the letter D?
glycolysis the citric acid cycle oxygen
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?
glycolysis and fermentation
Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?
mitochondrial intermembrane space
How will a healthy individual's ATP production change during an eight-hour fast?
The individual's ATP production will not change significantly.
Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation?
in all cells, with or without light
Beta oxidation generates substrates for cellular respiration through catabolism of which of the following molecules?
fatty acids
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 →→ oxyge
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
glycolysis
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 processes is driven by chemiosmosis?
oxidative phosphorylation
When a glucose molecule loses a hydrogen atom in an oxidation-reduction reaction, the glucose molecule is ________.
oxidized
What process occurs in structure H? What molecules belong in space A and B? What organelle is indicated by the letter C? What molecules belong in spaces E and F?
photosynthesis glucose and oxygen mitochondrion carbon dioxide and water
Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose?
the citric acid cycle
Glycolysis results in the net production of which of the following sets of molecules per glucose molecule?
2 NADH, 2 pyruvate, and 2 ATP
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
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
Anion and cation.
A covalent bond is likely to be polar when
one of the atoms sharing electrons is more electronegative than the other.
Considering this graph, under which condition is phosphofructokinase more active? Given what you know about glycolysis and regulation of metabolism by this enzyme, what is the mechanism by which phosphofructokinase activity differs depending on ATP concentration?
Phosphofructokinase is more active at low ATP concentration. Phosphofructokinase is an allosteric enzyme that is inhibited by ATP and stimulated by AMP.
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.
Which of the following is true for all exergonic reactions?
The reaction proceeds with a net release of free energy.
Which of the following is true of the energy levels of electrons in shells?
Valence electrons have a higher energy level than those in other filled shells.
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
Which of the following is the most correct interpretation of the figure?
ATP is a molecule that acts as an intermediary to store chemical energy for cellular work.
Two molecules with the chemical formulas C6H12O6 and C6H12O2 are probably
a monosaccharide and a fatty acid
1. When a compound donates (loses) electrons, that compound becomes Blank. Such a compound is often referred to as an electron donor.target 1 of 6 2. When a compound accepts (gains) electrons, that compound becomes Blank. Such a compound is often referred to as an electron acceptor.target 2 of 6 3. In glycolysis, the carbon-containing compound that functions as the electron donor is Blank.target 3 of 6 4. Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called Blank.target 4 of 6 5. Blank is the compound that functions as the electron acceptor in glycolysis.target 5 of 6 6. The reduced form of the electron acceptor in glycolysis isBlank.
1) Oxidized 2) Reduced 3) Glucose 4) Pyruvate 5) NAD⁺ 6) NADH
Blank donates electrons to the electron transport chain.target 1 of 5 Blank is a multi-protein complex within the electron transport chain.target 2 of 5 Blank is a nonprotein organic electron carrier within the electron transport chain.target 3 of 5 Blank is a prosthetic group present in several components of the electron transport chain.target 4 of 5 Blank is the final electron acceptor of the electron transport chain.
1. NADH 2. Complex III 3. Q 4. Fe-S 5. O2 molecular oxygen
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
Substrate-level phosphorylation accounts for approximately what percent of the ATP formed by the reactions of glycolysis?
100%
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. For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle. In cellular respiration, most ATP molecules are produced by _____. The final electron acceptor of aerobic cellular respiration is _____. During electron transport, energy from _____ is used to pump hydrogen ions into the _____. Structure A is
2 6 oxidative phosphorylation oxygen NADH and FADH2 ... intermembrane space ATP synthase
How many NADH are produced by glycolysis? In glycolysis, ATP molecules are produced by _____. Which of these is NOT a product of glycolysis? In glycolysis, what starts the process of glucose oxidation? In glycolysis there is a net gain of _____ ATP.
2 substrate-level phosphorylation FADH2 ATP 2
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)? 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? Which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle?
4 Oxaloacetate will accumulate and citrate will decrease. 3 ATP, 6 CO2, 9 NADH, and 3 FADH2
Approximately how much more free energy is supplied to the electron transport chain by NADH than by FADH2?
8 kcal/mol
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 liver cells, the inner mitochondrial membranes contain about five times the surface area of the outer mitochondrial membranes, which allows for increased production of which of the following below?
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
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.
Which of the summary statements below best describes the results of the following reaction? C6H12O6 + 6O2 →→ 6CO2 + 6H2O + Energy
C6H12O6 is oxidized and O2 is reduced.
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.
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 term describes the degree to which an element attracts electrons?
Electronegativity.
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 of the following molecules is the lowest-energy donor of electrons to the electron transport chain?
FADH2
Of the following lists of electron transport compounds, which one lists them in order from the one containing electrons with the highest free energy to the one containing electrons with the lowest free energy? Note that not all electron transport compounds in the electron transport chain are listed.
FADH2 -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2
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.
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
Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP? True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups. Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? Which step of the cellular respiration pathway can take place in the absence of oxygen? Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? Which of the following statements about the electron transport chain is true? Which stage of glucose metabolism produces the most ATP? True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.
Glucose True Fermentation Glycolysis Carbon dioxide NADH and FADH2 donate their electrons to the chain. Electron transport and chemiosmosis True
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
H+ concentration gradient across the membrane holding ATP synthase.
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, polar.
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
Ionic.
Which of the following statements best describes the electron transport chain?
It consists of a series of redox reactions.
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.
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.
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.
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 statements best describes a characteristic of NAD+?
NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle.
What is the correct order of electron transport compounds from best electron donor to best electron acceptor?
NADH -- Fe-S of Complex I -- Q -- Fe-S of Complex III -- Cyt c-- Cyt a of Complex IV -- O2
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
O2
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.
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.
Yeast growing in a medium containing glucose are moved to a medium without glucose but containing acetyl-CoA. Which of the following is the most likely effect on the amount of ATP and CO2 yeast cells will be able to produce with only acetyl-CoA as a fuel source versus glucose as the fuel source?
The amount of both ATP and CO2 produced per fuel molecule will decrease.
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.
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.
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.
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.
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 enters the citric acid cycle? In the citric acid cycle, ATP molecules are produced by _____. Which of these is NOT a product of the citric acid cycle?
acetyl CoA substrate-level phosphorylation acetyl CoA
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
What types of cells carry out ATP synthesis by chemiosmosis?
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
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
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
Most CO2 from catabolism is released during
the citric acid cycle.
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
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
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
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
In the process of cellular respiration, what is consumed and what is produced?
glucose is consumed and carbon dioxide is produced
In which reactions of cellular respiration does substrate-level phosphorylation occur?
in both glycolysis and the citric acid cycle
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
In muscle cells, fermentation produces _____. In fermentation _____ is reduced and _____ is oxidized.
lactate and NAD+ pyruvate ... NADH
Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?
oxidation of NADH to NAD+
Inhibition of which of the following metabolic pathways would result in a decrease of CO2 production compared to fully functional cellular respiration?
oxidation of pyruvate to acetyl CoA and the citric acid cycle
In mitochondria, exergonic redox reactions
provide the energy that establishes the proton gradient.
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
In the following reaction which molecule functions as the oxidizing agent? Pyruvate + NADH + H+ →→ Lactate + NAD+
pyruvate
What is the oxidizing agent in the following reaction? Pyruvate+NADH+H+→Lactate+NAD+
pyruvate
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
When a cell is deprived of oxygen, which of the following processes will be inhibited first?
the electron transport chain
Which of the following events takes place in the electron transport chain?
the harnessing of energy from redox reactions to generate a proton gradient
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
In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis?
two ATP
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
