What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
anabolic pathways
catabolic pathways
fermentation pathways
thermodynamic pathways
bioenergetic pathways
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction
gains electrons and gains energy.
loses electrons and loses energy.
gains electrons and loses energy.
loses electrons and gains energy.
neither gains nor loses electrons, but gains or loses energy.
When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a hydrogen ion) the molecule becomes
hydrogenated.
oxidized.
reduced.
redoxed.
a reducing agent.
Where does glycolysis takes place?
mitochondrial matrix
mitochondrial outer membrane
mitochondrial inner membrane
mitochondrial intermembrane space
cytosol
The ATP made during glycolysis is generated by
substrate-level phosphorylation.
electron transport
photophosphorylation.
chemiosmosis.
oxidation of NADH to NAD+.
The oxygen consumed during cellular respiration is involved directly in which process or event?
glycolysis
accepting electrons at the end of the electron transport chain
the citric acid cycle
the oxidation of pyruvate to acetyl CoA
the phosphorylation of ADP to form ATP
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
oxidative phosphorylation
chemiosmosis
Why are carbohydrates and fats considered high energy foods?
They have a lot of oxygen atoms.
They have no nitrogen in their makeup.
They can have very long carbon skeletons.
They have a lot of electrons associated with hydrogen.
They are easily reduced.
During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is
transferred to ADP, forming ATP.
transferred directly to ATP.
retained in the pyruvate.
stored in the NADH produced.
used to phosphorylate fructose to form fructose-6-phosphate.
In addition to ATP, what are the end products of glycolysis?
CO2 and H2O
CO2 and pyruvate
NADH and pyruvate
CO2 and NADH
H2O, FADH2, and citrate
In glycolysis, for each molecule of glucose oxidized to pyruvate
2 molecules of ATP are used and 2 molecules of ATP are produced.
2 molecules of ATP are used and 4 molecules of ATP are produced.
4 molecules of ATP are used and 2 molecules of ATP are produced.
2 molecules of ATP are used and 6 molecules of ATP are produced.
6 molecules of ATP are used and 6 molecules of ATP are produced.
A molecule that is phosphorylated
has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate.
has a decreased chemical reactivity; it is less likely to provide energy for cellular work.
has been oxidized as a result of a redox reaction involving the gain of an inorganic phosphate.
has an increased chemical reactivity; it is primed to do cellular work.
has less energy than before its phosphorylation and therefore less energy for cellular work.
Which kind of metabolic poison would most directly interfere with glycolysis?
an agent that reacts with oxygen and depletes its concentration in the cell
an agent that binds to pyruvate and inactivates it
an agent that closely mimics the structure of glucose but is not metabolized
an agent that reacts with NADH and oxidizes it to NAD+
an agent that blocks the passage of electrons along the electron transport chain
Why is glycolysis described as having an investment phase and a payoff phase?
It both splits molecules and assembles molecules.
It attaches and detaches phosphate groups.
It uses glucose and generates pyruvate.
It shifts molecules from cytosol to mitochondrion.
It uses stored ATP and then forms a net increase in ATP.
Starting with one molecule of isocitrate and ending with fumarate, what is the maximum number of ATP molecules that could be made through phosphorylation?
1
2
11
12
24
How many molecules of carbon dioxide (CO2) would be produced by five turns of the citric acid cycle?
5
10
60
How many reduced dinucleotides would be produced with four turns of the citric acid cycle?
1 FADH2 and 4 NADH
2 FADH2 and 8 NADH
4 FADH2 and 12 NADH
1 FAD and 4 NAD+
4 FAD+ and 12 NAD+
Cellular respiration harvests the most chemical energy from which of the following?
substrate-level phosphorylation
chemiosmotic phosphorylation
converting oxygen to ATP
transferring electrons from organic molecules to pyruvate
generating carbon dioxide and oxygen in the electron transport chain
During aerobic respiration, electrons travel downhill in which sequence?
food ® citric acid cycle ® ATP ® NAD+
food ® NADH ® electron transport chain ® oxygen
glucose ® pyruvate ® ATP ® oxygen
glucose ® ATP ® electron transport chain ® NADH
food ® glycolysis ® citric acid cycle ® NADH ® ATP
During oxidative phosphorylation, H2O is formed. Where does the oxygen for the synthesis of the water come from?
carbon dioxide (CO2)
glucose (C6H12O6)
molecular oxygen (O2)
pyruvate (C3H3O3-)
lactate (C3H5O3-)
In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP?
energy released as electrons flow through the electron transport system
energy released from substrate-level phosphorylation
energy released from ATP synthase pumping hydrogen ions from the mitochondrial matrix
energy released from movement of protons through ATP synthase
No external source of energy is required because the reaction is exergonic.
Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
It produces much less ATP than does oxidative phosphorylation.
It is found in the cytosol, does not involve oxygen, and is present in most organisms.
It is found in prokaryotic cells but not in eukaryotic cells.
It relies on chemiosmosis which is a metabolic mechanism present only in the first cells-prokaryotic cells.
It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.
Muscle cells, when an individual is exercising heavily and when the muscle becomes oxygen deprived, convert pyruvate to lactate. What happens to the lactate in skeletal muscle cells?
It is converted to NAD+
It produces CO2 and water.
It is taken to the liver and converted back to pyruvate.
It reduces FADH2 to FAD+
It is converted to alcohol.
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?
It was released as CO2 and H2O
Chemical energy was converted to heat and then released.
It was converted to ATP, which weighs much less than fat.
It was broken down to amino acids and eliminated from the body.
It was converted to urine and eliminated from the body.
Even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. When and where will this occur?
in photosynthetic cells in the light, while photosynthesis occurs concurrently
in non-photosynthesizing cells only
in cells that are storing glucose only
in photosynthesizing cells in dark periods and in other tissues all the time
in photosynthesizing cells in the light and in other tissues in the dark
The primary role of oxygen in cellular respiration is to
yield energy in the form of ATP as it is passed down the respiratory chain.
act as an acceptor for electrons and hydrogen, forming water.
combine with carbon, forming CO2
combine with lactate, forming pyruvate.
catalyze the reactions of glycolysis.
In liver cells, the inner mitochondrial membranes are about 5 X the area of the outer mitochondrial membranes, and about 17 X that of the cell's plasma membrane. What purpose must this serve?
It allows for increased rate of glycolysis.
It allows for increased rate of the citric acid cycle.
It increases the surface for oxidative phosphoryation.
It increases the surface for substrate-level phosphorylation.
It allows the liver cell to have fewer mitochondria.
The ATP made during fermentation is generated by which of the following?
the electron transport chain
aerobic respiration
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
ATP, CO2, and ethanol (ethyl alcohol).
ATP, CO2, and lactate.
ATP, NADH, and pyruvate.
ATP, pyruvate, and oxygen.
ATP, pyruvate, and acetyl CoA.
One function of both alcohol fermentation and lactic acid fermentation is to
reduce NAD+ to NADH
reduce FAD+ to FADH2
oxidize NADH to NAD+
reduce FADH2 to FAD+
none of the above
Which of the following statements describes NAD+?
NAD+ is reduced to NADH during both glycolysis and the citric acid cycle.
NAD+ has more chemical energy than NADH.
NAD+ is reduced by the action of hydrogenases.
NAD+ can donate electrons for use in oxidative phosphorylation.
In the absence of NAD+, glycolysis can still function.
A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of his condition?
His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
His cells cannot move NADH from glycolysis into the mitochondria.
His cells contain something that inhibits oxygen use in his mitochondria.
His cells lack the enzyme in glycolysis that forms pyruvate.
His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.
Where are the proteins of the electron transport chain located?
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the
formation of ATP.
reduction of NAD+.
restoration of the Na+/K+ balance across the membrane.
creation of a proton gradient.
lowering of pH in the mitochondrial matrix.
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?
glycolysis and the oxidation of pyruvate to acetyl CoA
oxidation of pyruvate to acetyl CoA and the citric acid cycle
the citric acid cycle and oxidative phosphorylation
oxidative phosphorylation and fermentation
fermentation and glycolysis
Inside an active mitochondrion, most electrons follow which pathway?
glycolysis ® NADH ® oxidative phosphorylation ® ATP ® oxygen
citric acid cycle → mc036-1.jpg → electron transport chain → ATP
electron transport chain ® citric acid cycle ® ATP ® oxygen
pyruvate ® citric acid cycle ® ATP ® NADH ® oxygen
citric acid cycle ® NADH ® electron transport chain ® oxygen
Where is ATP synthase located in the mitochondrion?
electron transport chain
outer membrane
inner membrane
Each time a molecule of glucose (C6H12O6) is completely oxidized via aerobic respiration, how many oxygen molecules (O2) are required?
6
38
Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in cellular respiration?
4
15
76
Recall that the complete oxidation of a mole of glucose releases 686 kcal of energy (ÄG = -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?
0.4%
25%
30%
40%
60%
The accompanying figure shows the electron transport chain. Which of the following is the combination of substances that is initially added to the chain?
oxygen, carbon dioxide, and water
NAD+, FAD, and electrons
NADH, FADH2, and protons
NADH, FADH2, and electrons
oxygen and electrons
Which metabolic pathway is common to both cellular respiration and fermentation?
Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle?
pyruvate
malate or fumarate
acetyl CoA
á-ketoglutarate
succinyl CoA
Which of the following is a true distinction between fermentation and cellular respiration?
Only respiration oxidizes glucose.
NADH is oxidized by the electron transport chain in respiration only.
Fermentation, but not respiration, is an example of a catabolic pathway.
Substrate-level phosphorylation is unique to fermentation.
NAD+ functions as an oxidizing agent only in respiration.
Most CO2 from catabolism is released during
glycolysis.
the citric acid cycle.
lactate fermentation.
electron transport.
oxidative phosphorylation.
Step shows a split of one molecule into two smaller moelecules.
Step involves an endergonic reaction.
Please wait - loading…