An organism is discovered that thrives in both the presence and absence of oxygen. Interestingly, as oxygen is removed from the organism's environment, the rate of sugar consumption increases while the growth rate decreases. What do these observations suggest about the likely identity of this organism?
It is a facultative anaerobic organism.
Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?
oxidation of NADH to NAD+
In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the production of which of the following sets of molecules?
ATP, CO2, and ethanol (ethyl alcohol)
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?
glycolysis and fermentation
Which of the following metabolic processes normally occurs regardless of whether or not oxygen (O2) is present?
glycolysis
What kinds of cells carry out ATP synthesis by chemiosmosis?
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements about these inside-out membrane vesicles is true?
The inside of the vesicles will become acidic when NADH is added.
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. After the disruption, which components involved in oxidative phosphorylation must be present for electron transfer and ATP synthesis to still occur?
all of the electron transport system and ATP synthase
A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. What is the most likely way that the lost fat left the body?
It was released as CO2 and H2O.
In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?
It increases the surface for oxidative phosphorylation.
If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
12.5
The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of which of the following processes?
coupling of an endergonic reaction to an exergonic reaction
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
30-32
Which of the following processes generates a proton-motive force in mitochondria?
pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space
Energy released by the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?
mitochondrial intermembrane space
In chemiosmosis, what is the most direct source of energy that is used to convert ADP + i to ATP?
energy released from movement of protons through ATP synthase, down their electrochemical gradient
Water is one of the end products of aerobic respiration. What is the source of the oxygen atom used in formation of the water?
molecular oxygen (O2)
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.
During aerobic respiration, which of the following molecules directly donates electrons to the electron transport chain at the lowest energy level?
FADH2
Where are the proteins of the electron transport chain located?
mitochondrial inner membrane
Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration?
glucose → NADH → electron transport chain → oxygen
Which of the following processes is driven by chemiosmosis?
oxidative phosphorylation
Which of the following statements about the electron transport chain is true?
It consists of a series of redox reactions
Which of the following events takes place in the electron transport chain?
the harnessing of energy from high-energy electrons derived from glycolysis and the citric acid cycle
Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?
acetyl CoA
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. Which of the following sets of products result from these reactions?
acetyl CoA, NADH, and CO2
Use the following information to answer the question below.
The citric acid cycle.
Starting with citrate, 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
Use the following information to answer the question below.
The citric acid cycle.
If pyruvate oxidation is blocked, what will happen to the levels
of oxaloacetate and citric acid in the citric acid cycle shown in the
accompanying figure?
Oxaloacetate will accumulate and citric acid will decrease.
Use the following information to answer the question below.
The citric acid cycle.
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
If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl CoA?
1/3
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
Use the following information to answer the question below.
The citric acid cycle.
If you were to add one of the eight citric acid cycle
intermediates to the culture medium of yeast growing in the
laboratory, what do you think would happen to the rates of ATP and
carbon dioxide production?
The rates of ATP production and carbon dioxide production would both increase.
Which electron carrier(s) function in the citric acid cycle?
NADH and FADH2
Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is stored in the form of which of the following molecules?
NADH
During which of the following metabolic processes is most of the CO2 from the catabolism of glucose is released?
the citric acid cycle
Which kind of metabolic poison would most directly interfere with glycolysis?
an agent that closely mimics the structure of glucose but is not metabolized
In glycolysis, for each molecule of glucose oxidized to pyruvate, ________.
two molecules of ATP are used, and four molecules of ATP are produced
Starting with one molecule of glucose, glycolysis results in the net production of which of the following sets of energy-containing products?
2 NADH, 2 pyruvate, and 2 ATP
The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol, and the free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?
Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?
100%
A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply?
Catabolic processes are activated that generate more ATP.
Why are carbohydrates and fats frequently considered high-energy foods?
They contain many electrons associated with hydrogen atoms.
The oxygen consumed during cellular respiration is directly involved in which of the following processes or events?
accepting electrons at the end of the electron transport chain
Which of the following statements about NAD+ is true?
NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes ________.
reduced
What happens to a glucose molecule when it loses a hydrogen atom as the result of an oxidation-reduction reaction?
The glucose molecule is oxidized.
Which of the summary statements below describes the results of the following reaction?
C6H12O6 is oxidized and O2 is reduced.
What happens when electrons are passed from one atom to a more electronegative atom?
The more electronegative atom is reduced, and energy is released.
Which of the following statements describes what happens to a molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction?
It loses electrons and loses potential energy.
In which reactions of cellular respiration and fermentation does substrate-level phosphorylation occur?
in both glycolysis and the citric acid cycle