CHAPTER 8—HARVESTING CHEMICAL ENERGY: CELLULAR RESPIRATION
MULTIPLE CHOICE
1. It has been thought that many diseases now associated with aging are related to malfunctioning
mitochondria. Why are the mitochondria so important to all cells?
a.
They produce energy in the form of ATP.
b.
They generate heat to keep the body warm.
c.
They are the source of all human disease.
d.
They are extremely large.
e.
They are located only in vital organs.
2. When individuals have mitochondrial disorders, why are the skeletal and heart muscles and the brain
most often affected?
a.
They are the most important organs.
b.
They have the highest energy needs.
c.
They are generally very fragile.
d.
They have fewer mitochondria in the cell.
e.
They are the most complex organs.
3. Which of the following types of organisms do NOT depend on mitochondria to survive?
a.
humans
b.
plants
c.
fungus
d.
protists
e.
bacteria
4. What is the ultimate source of chemical energy for all living organisms?
a.
photosynthesis
b.
cellular respiration
c.
ATP
d.
GTP
e.
glucose
5. Some organisms are not able to live in an environment where there is oxygen; these types of organisms
are called obligate anaerobes. Which of the following proposals is the most likely for how they survive
without oxygen?
a.
They are able to survive using less energy than aerobes.
b.
All of their ATP is imported into the cell from an external source.
c.
Sulfur is used instead of oxygen because it is chemically similar.
d.
These organisms use photosynthesis to produce energy.
e.
Their mitochondria are damaged, and consequently they are short-lived.
6. For a molecule to be reduced, it gains electrons from the environment. How else is a molecule
reduced?
a.
gaining hydrogen atoms
b.
losing hydrogen atoms
c.
gaining oxygen atoms
d.
losing oxygen atoms
e.
both losing hydrogen atoms and gaining oxygen atoms
7. When a molecule is reduced, it _________.
a.
gains electrons
b.
loses electrons
c.
stores electrons
d.
loses energy
e.
burns energy
8. Where would you expect to find proteins responsible for controlling the substances that enter and leave
mitochondria?
a.
plasma membrane of the cell
b.
inner mitochondrial membrane
c.
outer mitochondrial membrane
d.
nuclear membrane
e.
lysosomal membrane
9. What is the ultimate fate of oxygen gas (O2) in cellular respiration?
a.
It is respired as CO2.
b.
It is converted to water.
c.
It is attached to glucose.
d.
It is attached to pyruvate.
e.
It accepts electrons in glycolysis.
10. In the process of aerobic metabolism, carbon containing molecules are broken down and the energy
from the electrons is used for what purpose?
a.
to directly supply the energy needs of an organism
b.
to generate a proton gradient
c.
to alter enzyme structure
d.
to heat the organism in a cold environment
e.
to heat stored fat
11. Oxygen is able to allow electrons of a very low energy level to combine with it at the end of cellular
respiration and ultimately make water. How are the specific properties of oxygen beneficial to the
organism that uses it as a final electron acceptor?
a.
Oxygen is highly reactive and readily accepts electrons.
b.
Oxygen is strongly electronegative and helps pull the electrons through the electron
transport chain.
c.
Oxygen allows a maximum output of energy from ATP synthesis.
d.
Oxygen is the only molecule that can act as a final electron acceptor.
e.
Oxygen is highly reactive and readily oxidizes methane.
12. Oxidative phosphorylation is the process by which ____.
a.
high energy NADH is made to supply the cell with its needed energy
b.
a final electron acceptor is used indirectly to facilitate the production of ATP
c.
ATP is made using high energy intermediates of cellular respiration
d.
specific enzymes are regulated to control cellular respiration
e.
NAD+ is regenerated to allow glycolysis to continue
13. During which of the following processes is ATP NOT made DIRECTLY?
a.
glycolysis
b.
pyruvate oxidation
c.
citric acid cycle
d.
oxidative phosphorylation
e.
glycolysis and pyruvate oxidation
14. Which answer best describes energy flow in biological systems as described in the text?
a.
glucose → G3P → NADH → ATP
b.
bacteria → archaea → plants → animals
c.
NAD+ → NADH → ADP → ATP
d.
G3P → glucose → ATP → NAD+
e.
pyruvate oxidation → glycolysis → fermentation → citric acid cycle
15. In the absence of ATP synthase, animal cells would not be able to ____.
a.
create a proton gradient
b.
hydrolyze glucose to G3P
c.
carry out oxidative phosphorylation
d.
produce ATP
e.
carry out pyruvate oxidation
16. How are NADH and FADH2 related?
a.
They both directly produce ATP.
b.
They are both used in glycolysis.
c.
They both contain high energy phosphates.
d.
They both contain high energy electrons.
e.
They are both in the oxidized form.
17. What directly supplies the energy for oxidative phosphorylation?
a.
ATP
b.
NADH
c.
glucose
d.
proton gradient
e.
ATP synthase
18. What supplies the electrons for oxidative phosphorylation?
a.
ATP
b.
NADH and FADH2
c.
glucose
d.
proton gradient
e.
ATP synthase
19. How does cellular respiration differ in prokaryotes and eukaryotes?
a.
Eukaryotes use substrate-level phosphorylation; prokaryotes use oxidative
phosphorylation.
b.
Eukaryotes use mitochondria; prokaryotes use their plasma membrane.
c.
Eukaryotes use NAD+/NADH; prokaryotes use FAD+/FADH2.
d.
Eukaryotes do not all use oxygen; prokaryotes only use oxygen.
e.
Eukaryotes use only glucose; prokaryotes use only galactose.
20. What type of chemical reaction must occur for electrons to flow from one molecule to the next and
supply the energy for metabolism?
a.
acid/base
b.
reduction/oxidation
c.
exothermic
d.
trimolecular
e.
phosphorylation
21. If the inner membrane of the mitochondria were compromised in some way, what effect would this
have on cellular respiration?
a.
The transport of electrons across the inner mitochondrial membrane would not occur.
b.
The proton gradient across the inner mitochondrial membrane would dissipate.
c.
The ATP synthase enzyme would be denatured.
d.
The cell would generate more ATP than before.
e.
ATP would no longer be made anywhere in the cell by any mechanism.
22. During glycolysis, glucose molecules are broken down by breaking the carbon-hydrogen bonds that
are present and forming carbon-oxygen bonds. What is this chemical phenomena called?
a.
oxidation
b.
reduction
c.
protonation
d.
electrolysis
e.
pyruvate reduction
23. Glucose is a relatively stable molecule. It is activated in glycolysis by an initial step of _________.
a.
condensation
b.
hydrolysis
c.
oxidation
d.
phosphorylation
e.
reduction
24. The enzymes responsible for hydrolyzing glucose into G3P are found in what part of the cell?
a.
cytosol
b.
mitochondria
c.
rough ER
d.
nucleus
e.
cell membrane
25. The final product of glycolysis is ____.
a.
glucose
b.
fructose
c.
glyceraldehyde-3-phosphate
d.
pyruvate
e.
carbon dioxide
26. Which of the following substances is NOT produced at some point during glycolysis?
a.
ADP
b.
ATP
c.
NAD+
d.
NADH
e.
pyruvic acid
27. The various steps of glycolysis require a number of enzymes and small molecules. Which of the
following molecules are NOT required for glycolysis to take place?
a.
FAD
b.
NAD+
c.
ATP
d.
ADP
e.
phosphofructokinase
28. A toxic substance (compound x) had been found to inhibit glucose transport into mammalian cells. If
this substance was administered to a hamster, the likely cause of death would be from a lack of ____.
a.
NAD+ production
b.
ATP production
c.
GTP production
d.
CO2 production
e.
FAD production
29. The small molecule intermediate phosphoenol-pyruvate (PEP) is unusual due to which chemical
characteristic?
a.
supplies a high energy phosphate to phosphorylate ADP
b.
provides high energy electrons to make ATP
c.
its ability to carry out redox reactions
d.
regulates the activity of phosphofructokinase
e.
donates an electron to NAD+ and FAD
30. Which enzyme in the glycolysis pathway acts as a switch that can be regulated by ATP, ADP, and
NADH?
a.
pyruvate kinase
b.
triosephosphate isomerase
c.
aldolase
d.
ATP synthase
e.
phosphofructokinase
31. Which of these molecules has the most potential energy?
a.
glucose
b.
pyruvate
c.
ATP
d.
NADH
e.
FADH2
32. During which stages of cellular respiration is CO2 released?
a.
glycolysis
b.
pyruvate oxidation
c.
citric acid cycle
d.
electron transport system
e.
both pyruvate oxidation and citric acid cycle
33. Ultimately, the carbon molecules in pyruvate end up as what molecule?
a.
CO2
b.
acetate
c.
ATP
d.
CoA
e.
NADH
34. What is the function of NADH and FADH2?
a.
Both release energy for glycolysis to proceed forward.
b.
Both provide electrons to the electron transfer system.
c.
Both produce ATP by substrate-level phosphorylation.
d.
NADH delivers electrons, while FADH2 supplies H+.
e.
NADH is found only in the cytosol and FADH2 only in the matrix.
35. The electrons that are present in NADH and FADH2 are very high energy and theoretically sufficient
to produce ATP alone. Why then have biological systems evolved in a way to use the various steps of
cellular respiration to produce ATP?
a.
It would be less efficient to produce ATP directly from NADH and FADH2.
b.
There are insufficient amounts of ADP to phosphorylate and make ATP.
c.
All living organisms must use oxygen and therefore must carry out cellular respiration.
d.
The steps in respiration allow for a controlled release of energy in small increments.
e.
Not all cells have NADH and FADH2 present in their cytoplasm.
36. What molecule is responsible for carrying the acetyl group from pyruvate into the citric acid cycle?
a.
NADH
b.
FADH2
c.
ATP
d.
CoA
e.
oxaloacetate
37. When starting with a single molecule of glucose, how many times does oxidation occur during the
conversion of pyruvate to acetyl CoA in the process of cellular respiration?
a.
1
b.
2
c.
3
d.
4
e.
5
38. There are eight total steps in the citric acid cycle, and pyruvate is completely oxidized in steps three
and four. What is the purpose of the last four steps that occur in the cycle?
a.
to replenish the supplies of NAD+ and FAD
b.
to break down glucose into a three-carbon molecule
c.
to regenerate oxaloacetate to attach another acetate molecule
d.
to produce ATP by substrate-level phosphorylation
e.
to produce ATP by oxidative phosphorylation
39. What is the fate of CoA after it delivers an acetyl group into the citric acid cycle?
a.
It is degraded and used for energy.
b.
It is recharged with another acetate.
c.
It is used in protein synthesis.
d.
It remains in an inactive form until the cell dies.
e.
It is reused to start glycolysis.
40. Citrate synthase is the first enzyme in the citric acid cycle and is also able to be regulated to control the
amount of ATP that is produced as a result of the citric acid cycle. Why is early regulation the most
beneficial method for the cell?
a.
There is less wasted energy by regulating early steps.
b.
More ATP can be produced before the system is shut off.
c.
NADH is rarely found in the cell and needs to be conserved.
d.
The first enzyme is more amenable to regulation.
e.
There is no possible way to control the last enzyme in a pathway.
41. For every glucose molecule that goes through cellular respiration, how many times is a carbon atom
fully oxidized to CO2 in the citric acid cycle?
a.
1
b.
2
c.
3
d.
4
e.
5
42. Which molecule(s) is/are responsible for delivering the high energy electrons from the citric acid cycle
to the electron transfer system?
a.
NADH only
b.
FADH2 only
c.
Both NADH and FADH2
d.
Cyt C and Q
e.
ATP and ADP
43. We study cellular respiration because it is one of the most important pathways in biology. In fact,
nearly all carbohydrates at some point in their catabolism are directed through cellular respiration.
Why is it NOT necessary to have multiple independent pathways to break down different molecules?
a.
Using cellular respiration is theoretically the most efficient way to break down sugars and
other molecules.
b.
Oxygen must be used in the breakdown of all molecules in order to yield ATP.
c.
Greater complexity would lead to an eventual failure of the biological system.
d.
Most biological cells only catabolize one or two different types of sugars and only need
one main pathway.
e.
The molecules that are degraded are all structurally similar and relatively easily
interconverted.
44. Why is there more energy stored in fats as opposed to sugars?
a.
Fats are more prevalent in the body.
b.
Fats are more chemically related to ATP.
c.
Fats are processed differently after the citric acid cycle.
d.
Fats are in a more reduced state.
e.
Fats are in a more oxidized state.
45. What are the two main steps that must happen to a protein in order for it to be catabolized and broken
down by the citric acid cycle?
a.
The protein must be phophorylated and broken into amino acids.
b.
The protein must be glycosylated and transported to the liver.
c.
The protein must be hydrolyzed and the amino group removed.
d.
The amino group must be removed followed by the carboxyl group.
e.
The protein is broken into monomers and converted to acetate.
46. Oxygen acts as a final electron acceptor in respiration and is ultimately converted into which
molecule?
a.
water
b.
ATP
c.
CO2
d.
glucose
e.
phosphate
47. Glycolysis, pyruvate oxidation, and the citric acid cycle all have this molecule in common as one of
their products.
a.
CO2
b.
H2O
c.
ATP
d.
FADH2
e.
NADH
48. Compared to the cytoplasm, the mitochondrial matrix could be described as having ____.
a.
a low pH and high pyruvate concentration
b.
a high pH and high pyruvate concentration
c.
a low pH and low pyruvate concentration
d.
a high pH and low pyruvate concentration
e.
the same pH and pyruvate concentration