Chapter 8 Practice Quiz
In the 1940s, some physicians prescribed low doses of a drug called dinitrophenol (DNP) to help patients lose weight. This unsafe drug was quickly abandoned after a few patients died. DNP affects cells by uncoupling the chemiosmotic machinery and making the inner mitochondrial membrane "leaky" to hydrogen ions. Explain how DNP caused weight loss and, ultimately, death in these dieters.
No hydrogen ion gradient could be established, so little ATP was produced through the process of cellular respiration. In turn, consumed (dietary) energy and stored (fat) energy were metabolized to try to give the body enough ATP to survive, but without success.
Which of the following statements is TRUE of glycolysis? It produces more ATP than does aerobic respiration. It produces a net gain of ATP. It can be performed only by bacteria. It produces a net gain of FADH. It only takes place under anaerobic conditions.
It produces a net gain of ATP.
Bacteria in our mouths feed off the sugars in foods that we eat. As these bacteria ferment the sugars, they generate a product that can cause dental cavities. What is this product? Acetyl CoA Hydrochloric acid Citric acid Pyruvate Lactic acid
Lactic acid
How does a lack of oxygen affect energy availability in animals?
Low oxygen levels result in little ATP production via chemiosmosis and a switch to an anaerobic, and less efficient, fermentation pathway of metabolism.
Which of the following parts of the mitochondria is (are) directly involved in the synthesis of ATP during chemiosmosis? Inner membrane only Inner and outer membranes Matrix and inner membrane Matrix only Outer membrane only
Matrix and inner membrane
Glycolysis and the Krebs cycle reactions both occur in the mitochondria. True False
False
The process of fermentation is energetically more efficient than that of cellular respiration. True False
False
In vertebrate animal cells, where does the synthesis of lactate occur? Surface of ribosomes Fluid portion of the cytoplasm Mitochondrial inner membranes Mitochondrial matrix Nucleus
Fluid portion of the cytoplasm
Which event occurs in the fluid portion of the cytoplasm of a cell undergoing glucose metabolism? Electron transport Glycolysis Krebs cycle Acetyl CoA formation Chemiosmosis
Glycolysis
Which of the following is common to both fermentation and cellular respiration? Glycolysis Electron transport Conversion of pyruvate to acetyl CoA Reduction of pyruvate to lactate Krebs cycle
Glycolysis
Which of the following processes occurs in the cytoplasm? The ETC Glycolysis The Krebs cycle
Glycolysis
________ is the first stage in glucose metabolism and does not require oxygen.
Glycolysis
Why is it important that NAD+ molecules are regenerated during fermentation?
Glycolysis would stop when all the NAD+ molecules were used up, resulting in no energy production for that cell.
Which of the following most closely matches the correct order of the main events of aerobic cellular respiration? Glycolysis, major ATP production, pyruvate enters the mitochondrion, ETC, Krebs cycle Krebs cycle, ETC, major ATP production, glycolysis Glycolysis, Krebs cycle, ETC, major ATP production Glycolysis, pyruvate enters the mitochondrion, Krebs cycle, major ATP production, ETC Major ATP production, pyruvate enters the mitochondrion, Krebs cycle, ETC
Glycolysis, Krebs cycle, ETC, major ATP production
If only one molecule of pyruvate (instead of two) were produced per glucose molecule metabolized in glycolysis, then which of the following would be produced after glycolysis and before the electron transport chain? 1 ATP, 1 NADH, and 1 FADH2 1 ATP, 3 NADH, and 1 FADH2 1 ATP, 4 NADH, and 1 FADH2 2 ATP, 6 NADH, and 2 FADH2
1 ATP, 4 NADH, and 1 FADH2
Some people trying to lose weight have gone on the Atkins diet, in which they eat mostly high-protein, low-carbohydrate foods such as meat, cheese, and eggs. The amino acids in these protein-rich diets, such as alanine, glycine, and serine, can be converted to pyruvate by deamination (removal of the amino group). Based on this scenario as well as your knowledge of cellular respiration, how many ATP, NADH, and FADH2 molecules will be generated from one molecule of alanine during the mitochondrial matrix reactions? Hint: Only consider the reactions from the point at which the alanine carbons enter cellular respiration. 2 FADH2, 6 NADH, and 2 ATP 1 FADH2, 1 NADH, and 1 ATP 0 FADH2, 1 NADH, and 2 ATP 2 FADH2, 3 NADH, and 2 ATP 1 FADH2, 4 NADH, and 1 ATP
1 FADH2, 4 NADH, and 1 ATP
During glycolysis, what is the net gain of ATP molecules produced from one glucose molecule? 2 4 34 36 No ATP molecules are produced during glycolysis.
2
If no oxygen is available to a cell, then the net ATP production resulting from the metabolism of a single glucose molecule is no ATP. 1 ATP molecule. 2 ATP molecules. 32 ATP molecules. 36 ATP molecules.
2 ATP molecules.
In the absence of oxygen, suppose a single yeast cell undergoes fermentation and uses 100 molecules of glucose. How many molecules of ATP will be generated? 36 100 200 300 400
200
During aerobic respiration in cells, about ________ of the chemical energy in a metabolized glucose molecule is used for ATP production and the rest is released as heat. less than 1% 25% 40% more than 90%
40%
At the end of aerobic cellular respiration, how many total carbon dioxide molecules are produced for each glucose metabolized? 2 4 6 32 36
6
If ATP is made in the mitochondria, how does it provide energy for reactions in the cytoplasm of the cell? ATP is used to make glucose, which is transported to the cytoplasm. ATP is converted to ADP, which is transported to the cytoplasm and converted back to ATP. ATP diffuses into the cytoplasm through large pores in the outer membrane of the mitochondria out. The energy in ATP is converted to NADH, which travels to the cytoplasm. ATP is pumped out from the intermembrane space of the mitochondria to the cytoplasm.
ATP diffuses into the cytoplasm through large pores in the outer membrane of the mitochondria out.
Cyanide poisoning occurs because cyanide inhibits an enzyme in the electron transport pathway. Which of the following is the reason why cyanide poisoning becomes deadly? ATP is no longer produced by chemiosmosis. Glycolysis stops. Cells switch to anaerobic fermentation. Oxygen is reduced to water.
ATP is no longer produced by chemiosmosis.
The overall products of glycolysis are ATP and pyruvate only. ATP, NADH, pyruvate, and FADH2. ATP, NADH, FADH2, and CO2. ATP, NADH, and pyruvate. ATP, NADH, and acetyl CoA.
ATP, NADH, and pyruvate.
The products of the Krebs cycle include ATP only. carbon dioxide only. energy carriers only. carbon dioxide and energy carriers only. ATP, carbon dioxide, and energy carriers.
ATP, carbon dioxide, and energy carriers.
Chemiosmosis in mitochondria directly results in the synthesis of H2O. ATP. NADH. FADH2. acetyl CoA.
ATP.
The main function of cellular respiration is to produce CO2. ATP. NADH and FADH2. glucose.
ATP.
Which kind of metabolic poison would interfere with the glycolysis stage of cellular respiration? An agent that binds to lactate and inactivates it An agent that closely mimics the structure of glucose but is not capable of being metabolized and broken down An agent that inhibits the formation of acetyl CoA An agent that reacts with FADH2 and oxidizes FAD+ An agent that reacts with oxygen and depletes its concentration in the cell
An agent that closely mimics the structure of glucose but is not capable of being metabolized and broken down
How does baker's yeast in bread dough make the bread rise?
Bread rises due to the production of carbon dioxide during alcohol fermentation.
How does one account for the bubbles in a glass of beer or champagne? Lactate fermentation accounts for the bubbles. Bubbles of CO2 were produced by yeast during anaerobic metabolism and were trapped in the bottle. Bubbles of CO2, produced by aerobic respiration in yeast cells, were trapped in the beverage at bottling. Bubbles of CO2 were formed by the yeast cells during glycolysis. The bubbles are simply air bubbles resulting from the brewing process.
Bubbles of CO2 were produced by yeast during anaerobic metabolism and were trapped in the bottle.
Which of the following is an example of an electron-carrier molecule? Acetyl CoA Citric acid CO2 ATP NADH
NADH
________ is a series of reactions, occurring under aerobic conditions, in which large amounts of ATP are produced from the breakdown of glucose.
Cellular respiration
In aerobic cellular respiration, the ETC receives electrons directly from FADH2 only. ATP only. NADH and FADH2. NADH only. NADH and ATP.
NADH and FADH2.
________ is the process by which hydrogen ions move via a concentration gradient through ATP-synthesizing enzymes, resulting in the production of ATP.
Chemiosmosis
Where does the production of pyruvate occur during glycolysis? Mitochondrial matrix Inner membrane Ribosomes Cytoplasmic fluid Intermembrane compartment
Cytoplasmic fluid
Briefly compare and contrast the processes of cellular respiration and photosynthesis.
During photosynthesis, carbon dioxide and water are combined with light energy to produce glucose and oxygen. In cellular respiration, glucose, with oxygen, is broken down into carbon dioxide, water, and ATP. Both processes use chemiosmosis to produce ATP.
Which of the following metabolic processes directly utilizes oxygen? ETC Lactic acid fermentation Alcohol fermentation Glycolysis
ETC
The metabolic breakdown of one molecule of glucose generates the greatest amount of ATP energy during mitochondrial matrix reactions. ETC. glycolysis. the Krebs cycle. fermentation.
ETC.
During which step of aerobic respiration is oxygen used? Electron transport chain (ETC) Conversion of pyruvate to acetyl CoA Glycolysis Krebs cycle Fermentation
Electron transport chain (ETC)
What is the final electron acceptor in cellular respiration? NADH FADH2 Carbon dioxide Oxygen ATP
Oxygen
Some plans for weight loss include eating a low-carbohydrate diet. In the absence of a lot of glucose in the diet, what other food molecules can be used to extract energy for cellular respiration? Protein only Fats only Protein and fats
Protein and fats
Imagine that you are running a marathon, and at the end of the race, you sprint to the finish line. Describe how your muscle cells are getting energy. Discuss the processes involved and detail the differences that occur at the start of your run and toward the end of your run.
Students should address the shift from aerobic cellular respiration to anaerobic lactate fermentation as oxygen becomes scarce for the muscle cells. Cells obtain energy for their metabolic reactions from breaking down organic molecules with a high energy content. This energy is mostly stored as ATP molecules. At the start of the race the cells obtain energy using the aforementioned method. Under intense use, muscles require too much energy (ATP) and consume much more oxygen to produce that energy. High consumption leads to oxygen scarcity and the muscle cells begin to use lactic acid to satisfy their energy needs. In this situation at the end of the race, muscle pain, cramps and fatigue are due to the lactic acid being released.
The term chemiosmosis is associated with which process? The ETC Fermentation Glycolysis The Krebs cycle
The ETC
Which of the following processes involves hydrogen ions moving through ATP synthase channels, generating ATP molecules? Glycolysis The ETC The Krebs cycle
The ETC
Which of the following processes occurs across the mitochondrial membrane? The ETC Glycolysis The Krebs cycle
The ETC
Which of the following processes requires oxygen? Fermentation The ETC Glycolysis The Krebs cycle
The ETC
Which step produces the most ATP? The Krebs cycle The ETC Glycolysis
The ETC
During which of the following processes is CO2 produced? The Krebs cycle The ETC Glycolysis
The Krebs cycle
Which of the following processes involves citric acid? Glycolysis The ETC The Krebs cycle
The Krebs cycle
How do fatigued human muscle cells repay an "oxygen debt"? The cells increase production of ATP. The cells produce more oxygen. The cells decrease CO2 production. The cells convert glucose to pyruvate. The cells convert lactate back to pyruvate.
The cells convert lactate back to pyruvate.
How many CO2 molecules are generated from each pyruvate molecule that enters the mitochondrial matrix? One Two Three Four Five
Three
Carbon dioxide is considered a waste product of cellular respiration. True False
True
During chemiosmosis, a hydrogen ion gradient is linked to the production of ATP. True False
True
Respiration rates are measured by the amount of oxygen per gram of tissue per hour. In a series of experiments, it was determined that a warm-blooded mouse requires 2.5 milliliters of O2 per gram of tissue per hour, whereas a cold-blooded crayfish requires 0.047 milliliter of O2 per gram of tissue per hour. Why is there such a dramatic difference in respiration rates between these animals?
Warm-blooded animals require more energy to maintain their higher body temperature and greater metabolic rate, and energy production is directly proportional to oxygen utilization by the ETC.
We breathe more heavily during exercise because our cells are producing more CO2 and need to get rid of it. need more ADP to be converted to ATP. need more glucose to be broken down.
are producing more CO2 and need to get rid of it.
The reason bread dough "rises" is due to the production of ethanol. carbon dioxide gas. lactic acid. oxygen gas.
carbon dioxide gas.
Oxygen is necessary for cellular respiration because oxygen combines with carbon dioxide and water to form glucose. combines with electrons and hydrogen ions to form water. reduces glucose to form carbon dioxide and water. combines with carbon to form carbon dioxide. combines with electrons to form CO2.
combines with electrons and hydrogen ions to form water.
The inner membrane of the mitochondria can be compared functionally to the thylakoid membranes of the chloroplast because both contain a system for enzyme synthesis. electron transport. anaerobic respiration. pyruvate production. glucose synthesis.
electron transport.
In the mitochondrial matrix reactions, the original carbons in pyruvate end up in molecules of CO2. form glucose. are incorporated into molecules of NADH and FADH2. form the ring structure of oxaloacetic acid. form the backbone chain of citric acid.
end up in molecules of CO2.
During the final events of cellular respiration, oxygen combines with ________ to form ________. energy-depleted electrons only; water energy-depleted electrons and hydrogen ions; water hydrogen ions only; water carbon only; CO2 energy-depleted electrons and carbon; CO2
energy-depleted electrons and hydrogen ions; water
Yeast in a bottle of champagne produces ________ and ________.
ethanol; carbon dioxide
The conversion of glucose to lactate is a form of ________.
fermentation
The anaerobic breakdown of glucose is called the Krebs cycle. phosphorylation. fermentation. cellular respiration. chemiosmosis.
fermentation.
Within a cell undergoing anaerobic metabolism of glucose, fermentation occurs in the fluid portion of the cytoplasm. mitochondrial matrix. phospholipid bilayer of the cell membrane. nucleus. stroma of the chloroplast.
fluid portion of the cytoplasm.
In the process of cellular respiration, a molecule of ________ is completely broken down to form ________, ________, and ________.
glucose; H2O; ATP; carbon dioxide
In the cell, more than half of the energy produced by the metabolic breakdown of glucose is released as ________ and the remaining energy is stored in ________.
heat; ATP
For bacteria to continue growing rapidly when they shift from an aerobic environment to an anaerobic environment, they must produce ATP using NADH. increase the rate of glycolysis. increase the rate of the Krebs cycle. produce more ATP per molecule of glucose during glycolysis. increase the rate of glucose production.
increase the rate of glycolysis.
If glucose is metabolized under completely anaerobic conditions, pyruvate immediately enters the Krebs cycle. is converted to NADH. is converted by fermentation to lactate or CO2 + ethanol. is converted back to fructose until the concentration of oxygen increases. leaves the fluid portion of the cytoplasm and enters the mitochondrial matrix.
is converted by fermentation to lactate or CO2 + ethanol.
In human muscle cells, fermentation (by itself) produces water. adenosine triphosphate. pyruvate. lactate.
lactate.
Two possible end products of fermentation are ________ (as is produced by our muscle cells under anaerobic conditions) and ________ (as is produced by yeast under anaerobic conditions).
lactate; carbon dioxide (or ethanol)
Human muscle cells can perform alcoholic fermentation. lactic acid fermentation. aerobic cellular respiration. lactic acid fermentation and aerobic cellular respiration. alcoholic fermentation, lactic acid fermentation, and aerobic cellular respiration.
lactic acid fermentation and aerobic cellular respiration.
Most of the ATP produced during cellular respiration is generated in the mitochondrial ________ after the movement of hydrogen ions through ATP-synthesizing proteins in the inner membrane of the mitochondrion.
matrix
The part of a mitochondrion that is analogous to the stroma of a chloroplast is the grana. inner membrane. thylakoids. matrix. outer membrane.
matrix.
The organelles responsible for the bulk of ATP production via cellular respiration are the ________.
mitochondria
When oxygen is present most animal cells carry on fermentation and produce lactate. most animals convert CO2 to glucose. most animal cells utilize aerobic cellular respiration. two ATP molecules are produced for each glucose molecule. most bacteria and yeasts carry on fermentation.
most animal cells utilize aerobic cellular respiration.
After fermentation in human cells, lactate is converted to pyruvate in the lungs. muscles. bloodstream. bone marrow. heart.
muscles.
As a bicyclist pedals up a hill to the finish line of a race and "feels the burn" in his leg muscles, those muscle cells are most likely utilizing only oxygen for maximum ATP production. both cellular respiration and oxygen for maximum ATP production. only cellular respiration for maximum ATP production. some lactate fermentation and lactic starting to build up in his muscle tissue causing a cramp.
some lactate fermentation and lactic starting to build up in his muscle tissue causing a cramp.
In the Krebs cycle, electron-carrier molecules are produced as a result of individual reactions. NAD+ is reduced as one chemical compound is converted to another EXCEPT during the conversion of isocitrate to α-ketoglutarate. malate to oxaloacetate. α-ketoglutarate to succinate. succinate to fumarate.
succinate to fumarate.
All of the following are true statements about ATP EXCEPT that it is synthesized only within mitochondria. the molecule that all living cells rely on to do work. a short-term energy-storage compound. the cell's principal compound for energy transfers.
synthesized only within mitochondria.
The step in aerobic respiration that produces the most ATP per molecule of glucose is the ETC. glycolysis. alcohol fermentation. lactate fermentation. the citric acid cycle.
the ETC.
Some of the CO2 that is exhaled during breathing is created during the reduction of oxygen in the ETC. chemiosmosis. glycolysis. fermentation. the conversion of pyruvate to acetyl CoA.
the conversion of pyruvate to acetyl CoA.
During cellular respiration, the pyruvate produced in glycolysis is transported out of the mitochondria. broken down to O2 and hydrogen. the source of electrons for NADH and FADH2. converted to lactate or ethanol.
the source of electrons for NADH and FADH2.
At the end of glycolysis, the original carbons of the glucose molecule form two molecules of NADH. two molecules of citric acid. six molecules of carbon dioxide. two molecules of fructose. two molecules of pyruvate.
two molecules of pyruvate.
During the fermentation of one molecule of glucose, the net production of ATP is one molecule. two molecules. three molecules. six molecules. eight molecules.
two molecules.
The end product of glycolysis is one G3P molecule. one lactate molecule. two pyruvate molecules. two NAD+ molecules. two citric acid molecules.
two pyruvate molecules.
End products of the different fermentation processes include all of the following EXCEPT lactate. ethanol. water. carbon dioxide
water.