Cellular Respiration Practice Questions
How many molecules of FADH2 are generated during the citric acid cycle?
1
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed during glycolysis?
100%
For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.
2
How many molecules of ATP are produced during glycolysis (the net gain of ATP molecules)?
2
The net result of the breakdown of glucose in glycolysis and fermentation is the production of:
2 ATP
Assume a mitochondrion contains 58 NADH and 19 FADH2. If each of the 77 dinucleotides were used, approximately how many ATP molecules could be generated as a result of oxidative phosphorylation (chemiosmosis)?
212
How many molecules of ATP can be generated from one round of the citric acid cycle?
24
How many molecules of NADH are generated during the citric acid cycle?
3
Recall that the complete oxidation of a mole of glucose releases 686 kcal of energy (ΔG = -686 kcal/mol). The phosphorylation of ADP to form ATP stores approximately 7.3 kcal per mole of ATP. What is the approximate efficiency of cellular respiration for a "mutant" organism that produces only 29 moles of ATP for every mole of glucose oxidized, rather than the usual 36-38 moles of ATP?
30%
In aerobic respiration, the energy in 1 mole of glucose is capable of producing how many ATP molecules?
38 x (6.02 x 10^23) molecules of ATP
Each time a molecule of glucose (C6H12O6) is completely oxidized via aerobic respiration, how many oxygen molecules (O2) are required?
6
For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle.
6
How many carbon atoms are found in one molecule of glucose?
6
In glycolysis, the activation of glucose is accomplished by what?
ATP
Which molecule contains three phosphate groups?
ATP
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 fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.
As protons flow through the ______ , energy is released and exploited to combine ADP and inorganic phosphate to form ATP.
ATP synthase
What enters the citric acid cycle?
Acetyl-CoA
What is the starting material of the citric acid cycle?
Acetyl-CoA
Which of these is NOT a product of the citric acid cycle?
Acetyl-CoA
Ethanol is a product of which of the following processes?
Alcoholic fermentation
Respiration that occurs without oxygen is classified as what?
Anaerobic
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
In aerobic respiration carbohydrates are ultimately broken down into what?
Carbon dioxide
Products of the Krebs cycle include:
Carbon dioxide NADH FADH2
Most ATP produced in aerobic respiration occurs in what process?
Chemiosmosis
Examples of Coenzymes
CoA FAD NAD
In what part of the cell does glycolysis take place?
Cytosol
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
During which metabolic stage is glucose broken down to pyruvate?
Glycolysis
Which of the following events do not take place in the mitochondria?
Glycolysis
What type of metabolic reaction does not change the atomic make-up of the molecule involved?
Isomerization
Which stage in respiration produces the most coenzymes?
Krebs Cycle
Which stage of aerobic respiration produces ATP and NADH and releases CO2?
Krebs Cycle
What are the structural components of the mitochondria?
Matrix Inner membrane Intermembrane space
What is the main cellular structure involved in respiration?
Mitochondria
Where in an aerobic cell is NADH oxidized?
Mitochondria
During electron transport, energy from _____ is used to pump hydrogen ions into the _____.
NADH and FADH2 ... intermembrane space
What type of metabolic reaction involves a loss of electrons from the molecule involved?
Oxidation
Which of the following metabolic processes generates the most ATP?
Oxidative phosphorylation
The final electron acceptor in aerobic respiration is:
Oxygen
What molecule is essential for aerobic respiration to take place?
Oxygen
Which of the following is not a possible anaerobic glycolytic product?
Oxygen
The outer mitochondrial membrane is highly _________ while the inner membrane is _________.
Permeable, impermeable
What type of metabolic reaction involves the transfer of a phosphate group?
Phosphorylation
The high concentration of protons in the inner mitochondrial space relative to the mitochondrial matrix represents what kind of energy?
Potential energy
The most reduced compound formed in glycolysis is?
Pyruvate
What is not generated during the citric acid cycle?
Pyruvate
What is the end product of aerobic glycolysis?
Pyruvate
Which molecule does not freely cross the inner mitochondrial membrane?
Pyruvate
Products of glycolysis include:
Pyruvate ATP NADH
What type of metabolic reaction involves a gain of electrons by the molecule involved?
Reduction
What molecule is produced when oxygen is reduced by the electrons in the electron transport chain?
Water
You have a friend who lost 7 kg (about 15 pounds) of fat on a "low carb" diet. How did the fat leave her body?
You have a friend who lost 7 kg (about 15 pounds) of fat on a "low carb" diet. How did the fat leave her body?
The oxygen consumed during cellular respiration is involved directly in which process or event?
accepting electrons at the end of the electron transport chain
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate 1) loses a carbon, which is given off as a molecule of CO2, 2) is oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A. These three steps result in the formation of
acetyl CoA, NADH, H+, and CO2
In the presence of oxygen, all cells synthesize ATP via the process of glycolysis. Many cells also can metabolize pyruvate if oxygen is not present, via the process of:
fermentation
Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?
fermentation
Which molecule is metabolized in a cell to produce energy for performing work?
glucose
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
Which of the following normally occurs whether or not oxygen (O2) is present?
glycolysis
Where is ATP synthase located in the mitochondrion?
inner membrane
The proximate (immediate) source of energy for oxidative phosphorylation is _____.
kinetic energy that is released as hydrogen ions diffuse down their concentration gradien
In muscle cells, fermentation produces _____.
lactate and NAD+
Where are the proteins of the electron transport chain located
mitochondrial inner membrane
Energy released by the electron transport chain is used to pump H+ ions into which location?
mitochondrial innermembrane space
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?
oxidation of pyruvate to acetyl CoA and the citric acid cycle
The coenzyme NAD/NADH is involved in which of the following types of reactions?
oxidation/reduction
In cellular respiration, most ATP molecules are produced by _____.
oxidative phosphorylation
One function of both alcohol fermentation and lactic acid fermentation is to
oxidize NADH to NAD+.
The final electron acceptor of cellular respiration is _____.
oxygen
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
pyruvate, ATP, and NADH
In fermentation _____ is reduced and _____ is oxidized.
pyruvate, NADH
In the citric acid cycle, ATP molecules are produced by ____
substrate-level phosphorylation
Most CO2 from catabolism is released during
the citric acid cycle
In mitochondrial electron transport, what is the direct role of O2?
to function as the final electron acceptor in the electron transport chain
True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.
true
