CHAPTER 9—PHOTOSYNTHESIS
MULTIPLE CHOICE
1. In Engelmann’s classic experiment, why were the oxygen-requiring bacteria clustered around the
regions of Spirogyra algae that were bathed in red, blue, and violet light?
a.
Chlorophyll is green and thus reflects green light.
b.
The bacteria were immobile and that is where Engelmann happened to place them.
c.
Photosynthesis is most active in those wavelengths of light and thus more oxygen is
consumed by the algae in those regions.
d.
Photosynthesis is most active in those wavelengths of light and thus more oxygen is
produced by the algae in those regions.
e.
The most energy-rich wavelengths of light are found at the edges of visible and nonvisible
light (ultra violet and infrared).
2. If you want to buy a colored light bulb for your indoor plants, the least effective color would be
a.
red.
b.
blue.
c.
green.
d.
yellow.
e.
orange.
3. Suppose you explored a new planet and found a photosynthetic organism unlike any on Earth. You
repeat Engelmann’s classic experiment using this new organism in place of Spirogyra and find that
oxygen-dependent bacteria cluster near the green and yellow portions of the spectrum. What does this
tell you?
a.
The sun of this new planet emits different wavelengths of light than our own.
b.
This new organism is using yellow and green light to drive photosynthesis.
c.
This organism is green just like plants on Earth.
d.
This organism utilizes the most energy-rich photons of the spectrum.
e.
This new organism is using blue and red light to drive photosynthesis.
4. If the hydrogen atoms of water are radioactively labeled, which products of photosynthesis, if any, will
also have this radio-labeled hydrogen?
a.
water and oxygen gas both
b.
water only
c.
sugar only
d.
water and sugar both
e.
water, sugar, and oxygen gas
5. Which is the most correct statement about the role of photosynthesis in an ecosystem?
a.
Primary producers convert chemical energy to light energy.
b.
Primary consumers rely directly on light energy.
c.
Primary producers convert light energy to chemical energy as a service to the ecosystem,
not for their own gain.
d.
Primary consumers rely on primary producers to make light energy available in a usable
form.
e.
Primary producers are heterotrophs and thus make no contribution to the flow of energy
into the ecosystem.
6. Where does photosynthesis occur in eukaryotes?
a.
plasma membrane
b.
Golgi bodies
c.
cytosol
d.
mitochondria
e.
chloroplasts
7. Choose the most correct statement about the two phases of photosynthesis.
a.
The light-dependent reactions occur in the cytosol; the light-independent reactions occur
in the stroma.
b.
The products of the light-dependent reactions are ATP, NADPH, and O2; the products of
the light-independent reactions are ADP, NADP+, and sugar.
c.
The light-dependent reactions occur during the daylight hours; the light-independent
reactions occur when it is dark.
d.
The light-dependent reactions produce water as a by-product; the light-independent
reactions produce carbon dioxide as a waste product.
e.
The products of the light-dependent reactions are ADP, NADP+, and O2; the products of
the light-independent reactions are ATP, NADPH, and sugar.
8. If photosynthetic eukaryotic cells are provided with CO2 synthesized with heavy oxygen (18O), the 18O
label may be found in all but one compound. That compound is
a.
3-phosphoglycerate.
b.
cellulose.
c.
glucose.
d.
O2 gas.
e.
RuBP (Ribulose bisphosphate).
9. What absorbs the photons of light in photosynthesis?
a.
carotenoids
b.
chlorophyll
c.
chlorophyll and carotenoids
d.
the thylakoid membrane
e.
inner membrane of the chloroplast
10. Fluorescence occurs when
a.
a high-energy electron returns to its ground state by releasing energy in a photon.
b.
a low-energy electron moves to a high-energy state by absorbing heat.
c.
a high-energy electron leaves its nucleus and moves to a different molecule.
d.
a pigment molecule accepts a high energy electron and releases a photon of energy
e.
the energy from an electron is transferred to a different molecule while the electron returns
to the ground state.
Use the figure above for the following question(s).
11. In the figure above, diagram 1 represents
a.
a molecule of chlorophyll.
b.
a phospholipid in the thylakoid membrane.
c.
a primary electron acceptor.
d.
an accessory pigment.
e.
a carotenoid.
12. In the figure above, diagram 2 represents
a.
a molecule of chlorophyll.
b.
a phospholipid in the thylakoid membrane.
c.
a primary electron acceptor.
d.
a nonlight-reactive accessory pigment.
e.
a carotenoid
13. In the figure above, identify the photon absorbing region of chlorophyll.
a.
3
b.
4
c.
5
d.
6
e.
7
14. In the figure above, region 7 aids photosynthesis by
a.
splitting water.
b.
absorbing different wavelengths of light than chlorophyll.
c.
transferring hydrogen ions to chlorophyll.
d.
absorbing energy from chlorophyll.
e.
absorbing energy from cytochromes.
15. In the figure above, what absorbs photons of both blue and red light?
a.
5 with 3
b.
5 with 4
c.
5, regardless of the R group
d.
6
e.
7
16. In the figure above, what absorbs photons of light only in the blue/violet range and not light in the red
portion of the spectrum?
a.
5 with 3
b.
5 with 4
c.
5, regardless of the R group
d.
6
e.
7
17. Identify the hydrophobic side chain of chlorophyll in the figure above.
a.
5 with 3
b.
5 with 4
c.
5, regardless of the R group
d.
6
e.
7
18. The molecule of chlorophyll a in photosystem II’s reaction center is known as P680 because
a.
it absorbs 680 photons per minute.
b.
it absorbs photons with a wavelength of 680 nm.
c.
there are exactly 680 accessory pigments in the photosystem.
d.
it will generate 680 molecules of ATP per photon absorbed.
e.
there are 680 electrons that can be energized by light.
19. In the light-dependent reactions of photosynthesis, an excited electron from photosystem II is passed
along an electron transport chain to ___________.
a.
NAD+
b.
NADH
c.
photosystem I
d.
oxygen
e.
water
20. The chemical structure of chlorophyll is based on a complex organic ring structure, a long
hydrophobic side chain and an atom of _________ in the center of the ring.
a.
carbon
b.
manganese
c.
magnesium
d.
iron
e.
nitrogen
21. Each photosystem in a eukaryotic plant __________.
a.
is composed of molecules of chlorophylls and carotenoids.
b.
possesses a light-gathering antenna complex
c.
has a specialized chlorophyll a molecule in its reaction center
d.
a)., b). and c). are all true.
e.
a)., b). and c). are all true, but only for Photosystem II.
22. The molecule of chlorophyll a in photosystem I’s reaction center is known as P700 because
a.
it absorbs 700 photons per minute.
b.
it absorbs photons with a wavelength of 700 nm.
c.
there are exactly 700 accessory pigments in the photosystem.
d.
there are 700 molecules of NADPH generated per photon of light absorbed.
e.
there are 700 electrons that can be energized by light.
23. P700 is located in photosystem ____ and is comprised of chlorophyll ____ absorbing light with a
wavelength of 700 nm.
a.
I; b
b.
I; a
c.
II; b
d.
II; a
e.
I and II; a
24. All of the following processes are associated with photosystem I EXCEPT
a.
ATP synthesis.
b.
NADPH synthesis.
c.
cyclic electron flow.
d.
accepting electrons flowing from the electron transport chain.
e.
splitting of water.
25. All of the following are associated with photosystem II EXCEPT for
a.
the excitement of electrons to generate a proton gradient that will drive ATP synthesis.
b.
the transfer of electrons to NADP+ to generate NADPH.
c.
the splitting of water.
d.
the transfer of electrons to a primary electron acceptor.
e.
noncyclic electron flow.
26. The primary purpose of the light-dependent reactions is to
a.
provide electrons and energy for the light-independent reactions.
b.
generate O2 gas.
c.
make ADP in cyclic photophosphorylation.
d.
transfer electrons to the primary electron acceptors.
e.
produce sugars such as glucose.
27. The reason the light reactions have both cyclic and noncyclic electron pathways is
a.
because the light-independent reactions require ATP and NADPH in different amounts
than are generated by noncyclic electron flow.
b.
to ensure that ATP and NAPDH are generated in a 1:1 molar ratio.
c.
because only the combination of pathways can generate sufficient NADPH for the light-
independent reactions.
d.
to provide more electrons from water than would be released by the noncyclic pathway.
e.
because a single photon of light can’t energize a ground state electron in photosystem II to
the level necessary for transfer to photosystem I’s primary electron acceptor.
28. Suppose you recreate Jagendorf and Uribe’s chloroplast experiment with one small change: after
placing the chloroplasts (in the dark) in an acidic medium to fill the thylakoid membrane with protons,
you move the chloroplasts to a stronger acid rather than the basic solution used in the original
experiment. What would be the outcome of your experiment?
a.
ATP synthesis would still occur because a proton gradient was created.
b.
ATP synthesis would occur but at a slower rate because of the strength of the acid.
c.
ATP synthesis would not occur because the protons would reach equilibrium on both sides
of the thylakoid membrane and, thus, be unable to drive the activity of ATP synthase.
d.
ATP synthesis would not occur because the acid is too strong and would rupture the
thylakoid membrane.
e.
ATP synthesis would occur, but only until the protons reached equilibrium.
29. The following are all products of the light-independent reactions EXCEPT for
a.
O2 gas.
b.
ADP.
c.
NADP+.
d.
G3P.
e.
RuBP.
30. The purpose of the Calvin cycle is to
a.
produce sugars using CO2 as a carbon source.
b.
recover electrons lost when water was split.
c.
capture photons of light.
d.
counteract increasing atmospheric CO2 concentrations (global warming).
e.
generate O2 gas for cellular respiration.
31. Where do the electrons from NADPH go in the Calvin cycle?
a.
They are put onto oxygen, just like in cellular respiration.
b.
They are used to regenerate RuBP from G3P
c.
They are added to 3PGA.
d.
They are transferred to rubisco.
e.
They remain on NADPH to help drive the light reactions
32. Of the G3P generated in the Calvin cycle, 5/6 will be used to regenerate RuBP. A company
manufacturing widgets would go out of business if 5/6 of the widgets were recycled at the
manufacturing site rather than being sold. And yet plants survive this extreme inefficiency. Why?
a.
Actually, 5/6 of the G3P is used to build glucose and only 1/6 of the G3P is needed to
regenerate RuBP.
b.
Plants are extremely efficient in other ways and that compensates for this anomaly.
c.
There is unlimited CO2 for the plant to use, so it’s okay to “waste” some by regenerating
RuBP.
d.
The plant expends no energy to acquire the light energy that drives the Calvin cycle, so
there is no pressure on the system to become more efficient.
e.
The cyclic pathway of the light reactions compensates for the energy lost in RuBP
regeneration.
33. Where does the Calvin cycle occur?
a.
thylakoid membrane
b.
thylakoid lumen
c.
stromal lamellae
d.
cytosol
e.
stroma
34. The Calvin cycle requires all of the following molecules EXCEPT
a.
NADPH.
b.
ATP.
c.
CO2.
d.
rubisco.
e.
glucose.
35. You extract all of the proteins of a leaf and measure the percentage that is rubisco. You find that
rubisco comprises what percentage of the leaf proteins?
a.
10%
b.
25%
c.
50%
d.
75%
e.
90%
36. When Melvin Calvin and Andrew Benson reduced the CO2 available to cells in the photosynthesis
experiments, they discovered that RuBP accumulated. Why did this molecule accumulate?
a.
There wasn’t sufficient light to drive photosynthesis.
b.
The cells had too little ATP.
c.
There were not enough reactants to generate 3PGA.
d.
The RuBP was defective in structure and unable to form a bond with CO2.
e.
Rubisco was inhibited by the RuBP excess.
37. 2D chromatography is called that because
a.
there are two steps: labeling with a radioactive marker and separation via chromatography.
b.
the molecules are separated into a linear arrangement, meaning two dimensions.
c.
the process separates the molecules in two directions, first along the x axis and then along
the y axis.
d.
two different solutions are used in the paper chromatography process.
e.
two different types of radioactive markers must be used.
38. Rubisco has 16 subunits joined together to make a functional unit. Eight of the subunits are large, the
other 8 are small. Where on this enzyme are the active sites located?
a.
on each of the 8 large subunits
b.
on each of the 8 small subunits
c.
on one of the 8 large subunits
d.
on one of the 8 small subunits
e.
on each of the 16 subunits
39. Rubisco has 16 subunits joined together to make a functional unit. Eight of the subunits are large, the
other 8 are small. What is the function of the small subunit?
a.
The small subunits contain the reactant binding sites.
b.
It stabilizes the overall enzyme’s structure but has no function by itself.
c.
The function of the small subunit is still unknown.
d.
It regulates the enzyme’s rate of catalysis.
e.
The small subunits contain allosteric regulator binding sites.
40. Rubisco can add O2 to RuBP, which generates
a.
two molecules of 3PGA.
b.
two molecules of phosphoglycolate.
c.
three molecules of 3PGA.
d.
one molecule of G3P.
e.
a molecule of 3PGA and a molecule of phosphoglycolate.
41. Which molecule associated with photorespiration is toxic to plant cells?
a.
3PGA
b.
G3P
c.
phosphoglycolate
d.
glycolate
e.
rubisco
42. Why is photorespiration more likely in warm weather?
a.
Plants require warm weather (at least 23C) to drive photosynthesis.
b.
Plants are more likely to close their stomata in the daytime heat than at night when it is
cool.
c.
Plants are more likely to dehydrate in warm weather, forcing them to close the stomata to
conserve water; this prevents CO2 from entering the leaf.
d.
The rubisco enzyme is very temperature sensitive and becomes less selective in warmer
temperatures, allowing it to fix O2 instead of CO2.
e.
Plants use up the water in their central vacuoles in warm weather inhibiting the water-
requiring light reactions; this in turn alters the activity of rubisco.
43. The C4 cycle
a.
replaces the carbon fixation stage of the Calvin cycle.
b.
supplements the activity of rubisco by providing a second source of 3PGA for the
reduction stage of the Calvin cycle.
c.
is more efficient than the Calvin cycle because less ATP is consumed in the process.
d.
ensures that CO2 is provided to rubisco and thus prevents photorespiration.
e.
is most commonly associated with plants living in humid climates.
44. During which of the following time periods does a CAM plant use rubisco?
a.
daylight only
b.
in darkness only
c.
noon to midnight
d.
midnight to noon
e.
all 24 hours of a standard calendar day
45. During which of the following time periods does a C4 plant use rubisco?
a.
daylight only
b.
in darkness only
c.
noon to midnight
d.
midnight to noon
e.
all 24 hours of a standard calendar day
46. During which of the following time periods does a CAM plant take in atmospheric CO2?
a.
daylight only
b.
in darkness only
c.
noon to midnight
d.
midnight to noon
e.
all 24 hours of a standard calendar day
47. I‘m a botanist looking for new species of C4 plants. Where should I focus my search?
a.
Maine
b.
Quebec, Canada
c.
equatorial rainforest
d.
The Everglades (in Florida)
e.
Arizona
48. The products of the C4 cycle
a.
are immediately used in CAM plants.
b.
are stored by CAM plants in the central vacuole.
c.
are stored by CAM plants in the stroma.
d.
diffuse to bundle sheath cells for immediate use in C4 plants.
e.
are stored in mesophyll cells of C4 plants.
49. Photosynthesis occurs in _____, while respiration occurs in _____.
a.
plants, animals
d.
plants, plants and animals
b.
animals, plants
e.
plants and animals, plants and animals
c.
plants and animals, animals
50. Which of the following events probably made the evolution of cellular respiration possible?
a.
Accumulation of carbon dioxide in
atmosphere
d.
Emergence of eukaryotes
b.
Emergence of prokaryotes
e.
Emergence of plants
c.
Accumulation of oxygen in atmosphere