Biol 309
Test Question Bank
Cellular Energy
Multiple Choice
----------------------------(review ‘activation energy’ in Chapter 3)
1. The ‘activation energy’ of a chemical reaction would be best described as:
A. the difference in energy content of the substrate and the product.
B. the difference in energy content of the substrate and the transition state.
C. the amount of energy that remains in the products after the reaction.
D. the amount of energy an enzyme must contribute to the reaction.
2. Which of the following figures correctly shows the effect of an enzyme on the energy curve of
a chemical reaction? (solid line without enzyme, dashed line with enzyme)
-----------------------------3. During the process called "substrate level phosphorylation":
A. The energy for ATP synthesis comes directly from a substrate molecule.
B. ATP synthesis is catalyzed by the enzyme ‘ATP synthase’.
C. ATP is produced spontaneously, without the aid of enzymes.
D. Phosphorylation occurs on the "substrate side" of a membrane.
4. The “proton-motive force” that drives ATP synthesis in mitochondria and chloroplasts is an
example of:
A. a membrane transport protein
B. a hydrogen ion pump
C. an electrochemical gradient
D. substrate-level phosphorylation
5. Cytochrome proteins bind to electrons via (select all correct answers):
A. NAD
B. Fe-S groups
C. O2
D. amino acids
E. Heme
6. The terminal electron acceptor of mitochondrial electron transport is:
A. O2
B. H2O
C. CO2
D. ATP
E. NADH
7. During oxidative phosphorylation:
A. Acetyl-CoA is oxidized to yield NADH and FADH.
B. 4 ATP are produced per NADH.
C. energy is transferred directly from NADH to ATP.
D. a H+ gradient powers ATP synthesis.
Biol 309
Question Bank
Energy
Page 1
8. Within a plant, the Calvin cycle occurs:
A. only when O2 in abundant
B. in the light and in darkness
C. only in the dark
D. only in the absence of carbohydrates
E. only in the presence of light
9. The function of the light-independent reactions of photosynthesis is to:
A. release O2.
C. fix CO2 into organic molecules.
B. breakdown glucose and release CO2.
D. produce ATP and NADPH.
10. The “water-splitting” reaction of photosynthesis occurs:
A. in the final step of electron transport.
B. in the stroma of the chloroplasts.
C. in the reaction center of photosystem II.
D. During both photosystem I and photosystem II.
11. During photosynthesis:
A. CO2 is released during the Calvin cycle.
B. CO2 is absorbed during the light-independent reactions.
C. O2 is released in the light and CO2 is produced during the dark.
D. O2 is absorbed during the light-dependent reactions.
12. The Z-scheme diagram is used to depict:
A. the positions of the proteins in the cristae membrane of mitochondria.
B. changes in the energy level of electrons during the light-dependent reactions.
C. the path of energy flow between the light-dependent reactions and Calvin cycle.
D. None of the above answers are correct.
13. Which of the following statements correctly describes the process in plants called
photorespiration?
A. The process begins when the Rubisco enzyme reacts with O2 instead of CO2.
B. This refers to the activity of cellular respiration as it occurs in photosynthetic cells.
C. When photorespiration occurs, plants derive extra energy from photosynthesis.
D. During photorespiration, CO2 is a product of photosynthesis, instead of O2.
14. Ammonia (NH3) will shuttle H+ across a membrane from the more acidic side to the more
basic side. This happens because NH3 is protonated under acidic conditions (NH3 + H+ 
NH4+), then can freely diffuse across the membrane, and then is deprotonated under the more
alkaline side (NH4+  NH3 + H+). If mitochondria are treated with NH3, what would be the
expected effect on respiration?
A. NADH will accumulate in the mitochondria.
B. The rate of ATP synthesis will increase dramatically.
C. Chemiosmotic ATP synthesis will cease.
D. O2 consumption will decrease.
Biol 309
Question Bank
Energy
Page 2
True or false
1. Energy is released during the following reaction: ATP ---------> ADP + Pi
2. The more negative its redox potential, the more strongly does a protein bind electrons.
3. In this process:
NADH + ATP + Pi  NAD + ATP
A. NADH is oxidized.
B. ATP is reduced.
4. The pH of the matrix is normally lower than that of the intermembrane space.
5. Like all enzymes, the ATP synthase reaction is reversible under suitable conditions.
6. Thylakoid and cristae membranes serve similar functions.
7. In both mitochondria and chloroplasts, H+ are stored in the space between the inner and outer
membranes of the organelle.
8. ATP and NADPH are used by Rubisco during the CO2 fixation reaction.
9. An “antenna complex” is associated with both PSI and PSII.
10. ATP is the terminal electron acceptor of the light-dependent reactions of photosynthesis.
11. The end-product of photosynthesis that is exported from the chloroplast is glyceraldehydephosphate.
12. The electrons transported during photosynthetic electron transport originate from NADH.
13. ATP is the terminal electron acceptor of the light-dependent reactions of photosynthesis.
14. The ATP synthases of mitochondria and chloroplasts are structurally and functionally
similar.
15. O2 is a waste product of photosynthesis.
Fill-in, etc.
1. In mitochondria, electrons are stripped from NADH by the _______________________
complex and pass to the small lipid-soluble molecule called _________________.
Biol 309
Question Bank
Energy
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2. The NADH used for oxidative phosphorylation are produced during the
______________________ and _______________ stages of cellular respiration.
3. The chlorophyll molecule is embedded in the _______________ membranes of the chloroplast
by its hydrophobic tail. The light-absorbing part of the molecule is called the
__________________ ring.
4. During photosynthetic electron transport, light energy is absorbed into a cluster of pigment
molecules called a ___________________ and resonantly focused into the
_________________________ of Photosystem ___.
5. The electrons used in photosynthesis originate from ______, and then pass through an electron
transport complex called ________________________ to Photosystem- ___.
6. What three components needed to make ATP via oxidative phosphorylation are missing from
this list: membrane, electron-transporting H+ pumps, ATP synthase, ADP, H+
_________ __________ _________
7. Choosing from the following list, identify the cellular compartment(s) in which each of the
following is located
cytosol, stroma, thylakoid membranes, thylakoid lumen, chloroplast intermembrane space
matrix, cristae, mitochondrial intermembrane space, mitochondrial outer membrane
Krebs cycle enzymes _______________
Rubisco
_______________
glycolytic enzymes _______________
Calvin-Bensen cycle enzymes ______________
Cytochrome oxidase
ATP synthase
P680 reaction center
high [H+]
_______________
_______________
_______________
_________________
8. What is wrong with this statement: “In plants, O2 is produced during photosynthesis so that it
is available for use during cellular respiration.”?
9. Draw a line connecting the compartments and membranes that serve analogous functions in
chloroplasts and mitochondria. (not all will be connected)
Chloroplasts
Mitochondria
outer chloroplast membrane
inner chloroplast membrane
intermembrane space
stroma
thylakoid membrane
thylakoid lumen
outer mitochondrial membrane
cristae membrane
intermembrane space
matrix
Biol 309
Question Bank
Energy
Page 4
10. The electron transport chain and ATP synthase of prokaryotes exists within the cell
membrane, and hydrogen ions are pumped to the outside of the cell.
A. Draw a simple diagram of a prokaryotic cell showing this arrangement, and indicate the
directions of H+ flow linked to the e- transport proteins and through the ATP synthase.
B. How does the endosymbiotic theory explain the origin of the mitochondria inner and
outer membranes?
C. Explain how the location of chemiosmotic ATP synthase in prokaryotes supports the
endosymbiotic theory of mitochondrial origin.
D. What is other evidence of the endosymbiotic origin of mitochondria?
11. In the Hill reaction experiment that we perform in the lab, spinach leaves are fractionated to
yield thylakoid membranes free of the surrounding stroma and metabolites. These can be
stimulated to carry on electron transport in the light if the electron acceptor DCPIP is provided.
DCPIP absorbs electrons from the b6/f cytochrome complex, and changes in color from blue to
clear as it becomes reduced – a change that can be measured to follow the rate of electron
transport.
A capstone student studied the effect of 3 substances on the rate of photosynthetic
electron transport (PET) as measured by the Hill reaction:
Hydroxylamine -- an electron donor to the P680 reaction center
Simazine -- a PET inhibitor at P680
DSPD -- a PET inhibitor after P700
For each experiment, PET was allowed to proceed for a while only in the presence of DCIP.
[Note that because DCPIP becomes clear as it accepts electrons, the absorbance of the thylakoid
suspension decreases as PET occurs.] After initially establishing that PET was occurring
normally, a test substance was then added to the mixture (at the time points indicated by the
arrows in the Figure). Unfortunately, the student forgot to label the test tubes, and thus was
unsure which molecule was used in each experiment. Based upon the results shown below,
which substance appears to have been added in experiments 1, 2, and 3? Explain each.
Experiment 1
Experiment 2
Experiment 3
Absorbance
1.0
0.5
0
Time
Biol 309
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Energy
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12. Complete the following diagram of the cristae membrane of mitochondria
13. Identify the metabolites labeled in this diagram:
A. ______ & B. ______
C. ______ & D. _____
E. ______ & F. _______
G. ______ & H. ______
J. ______
choose from: ATP, ADP + Pi, NAD, NADH
NADP, NADPH, CO2, H2O
FAD, FADH
14. Identify each component, reactant and product of the photosynthetic reactions labeled with a
“?” in the diagram below.
Biol 309
Question Bank
Energy
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15. If we are measure the rate of photosynthesis in intact leaves, as we do in the photosynthesis
experiment of Intro Biology, we get a curve (the ‘light saturation curve’) similar to that shown
here.
A. Do the light dependent or independent reactions
limit the rate of photosynthesis during the linear
phase? Explain.
B. Which of the following conditions will increase the
value of X?
1. Increasing the number of reaction centers
2. Adding an uncoupler
3. Increasing the concentration of CO2
4. Further increasing the light intensity
16. As we discussed, chloroplasts can be purified and fractionated into either purified thylakoids
or the enzymes of the stroma. Suppose that you wanted to demonstrate the different reactions of
photosynthesis, what are the minimum constituents that you need to combine together in order to
have a system that will produce:
A. 3-phosphogyceraldehyde
Constituent choices:
B. 3-phosphoglyceric acid
Thylakoids
NADPH
C. NADPH
Stroma
NADP
D. O2
ATP
RUBP
E. The rate of the reaction would increase for
which of the above reactions if an ATP
synthesis uncoupler were added? Explain.
Biol 309
Question Bank
ADP &Pi
Glucose
Assume that CO2 is freely available
through diffusion from the air.
Energy
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