Cellular Respiration and Fermentation
Each ATP molecule contains about 1% of the amount of chemical energy available from the complete oxidation of a single glucose molecule. Cellular respiration produces about 32 ATP from one glucose molecule. What happens to the rest of the energy in glucose?
It is converted to heat.
The function of cellular respiration is to __________. (
extract usable energy from glucose
Which of the following best describes the electron transport chain?
Electrons are passed from one carrier to another, releasing a little energy at each step
Most of the ATP produced in cellular respiration comes from which of the following processes?
Oxidative phosphorylation
During the reaction C6H12O6 + 6 O2 → 6 CO2 + 6 H2O, which compound is reduced as a result of the reaction?
Oxygen
In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?
Pyruvate is oxidized, and a molecule of carbon dioxide is removed. The electrons removed in this process are used to reduce NAD+ to NADH.
Where do the reactions of glycolysis occur in a eukaryotic cell?
The cytosol
Energy for synthesizing ATP is obtained by ATP synthase directly from which of the following processes?
The flow of H+ across the inner mitochondrial membrane through the ATP synthase enzyme
If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result?
The muscle cells will have more trouble making enough ATP to meet their energy requirements. The cells will not be able to carry out oxidative phosphorylation. The cells will consume glucose at an increased rate.
When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?
The pH of the matrix increases.
A small amount of ATP is made in glycolysis by which of the following processes?
Transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation
In the citric acid cycle, for each pyruvate that enters the cycle, one ATP, three NADH, and one FADH2 are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle?
Two ATP, six NADH, two FADH2
Two molecules with the chemical formulas C6H12O6 and C6H12O2 are probably
a monosaccharide and a fatty acid
In the overall process of glycolysis and cellular respiration, __________ is oxidized and __________ is reduced.
glucose; oxygen In cellular respiration, electrons and hydrogen are removed from glucose and added to oxygen.
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
glycolysis
A molecule becomes more oxidized when it __________.
loses an electron
Of the listed metabolic pathways, which is the only pathway found in all organisms?
Glycolysis
How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen?
4
Which of the following substances is/are involved in oxidative phosphorylation?
ADP Oxygen ATP
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.
During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes?
At the end of the electron transport chain to accept electrons and form H2O
A gram of fat oxidized by respiration produces approximately twice as much ATP as a gram of carbohydrate. Which of the following best explains this observation?
Fats are better electron donors to oxygen than are sugars.
Which of the following represents the major energy-related accomplishment of the citric acid cycle, even though it is not the only energy-related accomplishment?
Formation of NADH and FADH2
Which of the following molecules in the process of glycolysis possesses the most chemical energy?
Fructose-1,6-bisphosphate
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
H+ concentration across the membrane holding ATP synthase.
When solid tumors of animals reach a certain size, the center of the tumor begins to die. To prevent this, the tumor can recruit new blood vessels. What purpose does the recruitment of blood vessels to growing tumors serve?
It supplies oxygen so that aerobic cellular respiration can occur instead of fermentation, and it supplies glucose to the rapidly dividing cells of the tumor.
Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of which of the following compounds?
Lactate
If significant amounts of materials are removed from the citric acid cycle to produce amino acids for protein synthesis, which of the following will result?
Less ATP will be produced by the cell. Less CO2 will be produced by the cell. The four-carbon compound that combines with acetyl CoA will have to be made by some other process.
Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria?
Movement of electrons down the electron transport chain
In glycolysis in the absence of oxygen, cells need a way to regenerate which compound?
NAD+
When a poison such as cyanide blocks the electron transport chain, glycolysis and the citric acid cycle also eventually stop working. Which of the following is the best explanation for this?
NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.
After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of __________.
NADH
Which of the following is a correct description of the events of cellular respiration in proper sequence?
Oxidation of glucose to pyruvate; oxidation of pyruvate; citric acid cycle; oxidative phosphorylation
The energy given up by electrons as they move through the electron transport chain is used in which of the following processes?
Pumping H+ across a membrane
Most of the electrons removed from glucose by cellular respiration are used for which of the following processes?
Reducing NAD+ to NADH in glycolysis and the citric acid cycle Producing a proton gradient for ATP synthesis in the mitochondria
Muscle tissues make lactate from pyruvate to do which of the following?
Regenerate NAD+
Which of the following events accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle?
Release of CO2 and synthesis of NADH
Which of the following statements is the best explanation of what happens to the temperature and carbon dioxide concentration during a 1-hour class period in a classroom of 300 students if the heating and air-conditioning is turned off and all doors are kept closed?
Temperature and the level of carbon dioxide rise as heat and carbon dioxide are by-products of cellular respiration.
If a compound that allows protons to freely diffuse across membranes is added to cells that are actively metabolizing glucose via cellular respiration, which of the following processes would stop?
The chemiosmotic synthesis of ATP would stop in the mitochondria, but substrate-level phosphorylation could continue
Which of the following processes generates most of the NADH that delivers electrons to the electron transport chain?
The citric acid cycle
Why is the citric acid cycle called a "cycle"?
The four-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the cycle.
Where do the reactions of the citric acid cycle occur in eukaryotic cells?
The matrix of the mitochondrion
There is no production of carbon dioxide in glycolysis. Which of the following is the best explanation for this fact?
The products of glycolysis contain the same total number of carbon atoms as in the starting material
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.
When protein molecules are used as fuel for cellular respiration, __________ are produced as waste.
amino groups
In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen. The mice were closely monitored, and after a few minutes, radioactive oxygen atoms showed up in __________.
carbon dioxide
Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step __________.
enables the cell to recycle the reduced NADH to oxidized NAD+
Which of the following is the process in which glucose is oxidized to generate two molecules of pyruvate and in which ATP and NADH are produced?
glycolysis.
A chemist has discovered a drug that blocks phosphoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to kill bacteria in people with infections. However, he cannot do this because __________.
human cells must also perform glycolysis; the drug might also poison them
A covalent bond is likely to be polar when
one of the atoms sharing electrons is more electronegative than the other.
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
oxygen.
In mitochondria, exergonic redox reactions
provide the energy that establishes the proton gradient.
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ S Lactate + NAD+
pyruvate
Most CO2 from catabolism is released during
the citric acid cycle.
In eukaryotic cells, the components of the electron transport chain are located in or on __________.
the inner membrane of the mitochondrion
Oxygen gas (O2) is one of the strongest oxidizing agents known. The explanation for this is that __________.
the oxygen atom is very electronegative
In brewing beer, maltose (a disaccharide of glucose) is __________.
the substrate for alcoholic fermentation