Chapter 21—Photosynthesis
MULTIPLE CHOICE
1. Photosynthesis occurs in photosynthetic ____ localized in large organelles known as ____.
a.
membranes; chloroplasts
b.
proteins; ribosomes
c.
matrix; chloroplasts
d.
membranes; photoplasts
e.
none are true
2. The reaction of photosynthesis whereby light energy is transduced into chemical energy uses ____ as a
source of carbon, and produces ____.
a.
CO2; hexose
b.
hexose; CO2
c.
acetyl CoA; hexose
d.
CO2; acetyl CoA
e.
none of the above
3. All are contained by chloroplasts EXCEPT:
a.
thylakoid membrane.
b.
ribosomes.
c.
DNA and RNA.
d.
stroma.
e.
all are true.
4. Chloroplasts consist of a folded inner membrane called the ____, which is organized into paired folds
called ____.
a.
thylakoid membrane; stroma
b.
lamellae; thylakoid membrane
c.
thylakoid membrane; lamellae
d.
stroma; thylakoid membrane
e.
lamellae; stroma
5. Balance the following reaction:
____ NADPH + ____ H+ + ____ ATP + ____ CO2 + 12 H2 O → C6H12O6 + 12 NADP+ + 18 ADP + 18
Pi
a.
6; 6; 18; 6
b.
12; 12; 18; 3
c.
6; 6; 12; 6
d.
12; 12; 18; 6
e.
6; 6; 12; 3
6. Chloroplasts differ from mitochondria in that:
a.
chloroplasts can not generate ATP.
b.
only mitochondria have a double membrane.
c.
in chloroplasts, the proton gradient is generated between the thylakoid lumen and the
stroma.
d.
only the mitochondrion has DNA, RNA and ribosomes.
e.
chloroplasts do not utilize a Q-cycle.
7. Characteristics of chlorophyll include all EXCEPT:
a.
iron-containing porphyrin.
b.
planar conjugated porphyrin ring.
c.
long-chain phytol tail.
d.
delocalized electrons in the aromatic ring.
e.
photoexcitable electrons.
8. Carotenoids have primary roles in photosynthesis as:
a.
accessory light-harvesting and photooxidation.
b.
accessory light-harvesting and photoprotection from reactive oxygen species.
c.
resonance transfer pigments and photooxidation.
d.
resonance transfer and photodiffusion protection.
e.
none are true.
9. Which of the following statements about the light reactions of photosynthesis is true?
a.
There are two distinct photosystems, linked together by a mechanism similar to electron
transport.
b.
The source for electrons is located in the stroma of the thylakoid.
c.
The Mn complex is the primary electron acceptor and is located on photosystem I.
d.
The ultimate electron donor is molecular oxygen.
e.
Plastoquinone is a fixed electron transporter in the system located in the inner membrane.
10. The light reactions in photosynthetic plants:
a.
reduce water to oxygen with the production of NADPH
b.
use NADP+ to oxidize water to oxygen, thus forming NADPH
c.
produce ATP and NADPH during cyclic photophosphorylation.
d.
involve the splitting of two water molecules to produce molecular oxygen.
e.
uses photons of visible light to effect the reduction of water to oxygen
11. When light energy is absorbed by chlorophyll an electron is promoted to a higher orbital and then
transferred to a suitable acceptor resulting in light energy conversion to chemical energy in a(n):
a.
isomerase reaction.
b.
mutase reaction.
c.
ligase reaction.
d.
oxidation-reduction reaction.
e.
none of the above.
12. If A and B represent electron-transfer molecules adjacent to chlorophyll (Chl) in the membrane, fill in
the reaction sequence:
a.
Chl; Chl; A−; Chl+; B−
b.
Chl*; Chl*; A−; Chl; B+
c.
Chl*; Chl*; A+; Chl−; B+
d.
Chl−; Chl−; A+; Chl; B−
e.
Chl−; Chl−; A−; Chl+; B−
13. The photosynthetic unit includes all EXCEPT:
a.
antenna chlorophylls.
b.
the reactive center.
c.
oxidation of chlorophyll to a cationic free radical, Chl .+ .
d.
the cationic free radical is the Mg2+ ion.
e.
all are true.
14. Properties of photosystem II (PSII) include all EXCEPT:
a.
light-driven O2 evolution.
b.
similar photosystem in photosynthetic bacteria.
c.
use quinines as terminal electron acceptors.
d.
found in cyanobacteria, green algae and higher plants.
e.
all are true.
15. Chlorophyll is located in the ____ of the chloroplast.
a.
thylakoid membranes associated with proteins
b.
thylakoid spaces associated with rubisco
c.
stroma
d.
inner membrane space
e.
outer membrane
16. Many chlorophyll molecules absorb light and direct the energy to the reactive centers. The transfer of
this absorbed energy is called:
a.
fluorescence transfer.
b.
redox transfer.
c.
resonance energy transfer.
d.
photochemical emission.
e.
energy transduction.
17. All of the following are involved in the production of biochemical energy from light EXCEPT:
a.
electron transfer.
b.
Q-cycle.
c.
transmembrane pH gradient.
d.
ribulose-1,5-bisphosphate.
e.
chlorophyll.
18. How many photons of light must be absorbed by PSII for the oxidation of 2 water molecules to form
one oxygen molecule?
a.
2
b.
4
c.
6
d.
8
e.
16
19. The essence of photosynthesis is the photochemical event which is:
a.
conversion of H2O to O2.
b.
reduction of NADP+.
c.
phosphorylation of ADP.
d.
light energy transduction to chemical energy.
e.
fixation of CO2.
20. All are properties of both the P700 and P680 reaction centers EXCEPT:
a.
contain chlorophyll dimers.
b.
are electron donors.
c.
are activated by visible light.
d.
are involved in light-driven O2 evolution.
e.
all are properties.
21. Via PSII and PSI, electrons ultimately flow from ____ to ____.
a.
NAPDH; O2
b.
NADP+; water
c.
water; NADP+
d.
O2; NADPH
e.
None are true
22. The product(s) of the R. viridis photosynthetic reaction center is (are):
a.
mobile reduced quinone.
b.
NADPH.
c.
O2.
d.
reduced ferredoxin.
e.
protons.
23. The quantum yield of photosynthesis can be defined as the amount of ____ formed per equivalent of
____.
a.
photons; light input
b.
product; light input
c.
ATP; coenzyme Q
d.
carbohydrate; ATP
e.
none are true
24. Which statement regarding light is NOT true?
a.
the energy of a photon of light is calculated by E=h
b.
the energy of 700nm light is greater than that of 400nm light
c.
photosynthesis allows two electrons to flow for each pair of photons absorbed per center
d.
the quantum yield of photosynthesis can be described as CO2 fixed per photon absorbed,
or O2 evolved per photon absorbed
e.
none are true
25. Photophosphorylation is the term for:
a.
activation of enzymes with light
b.
ATP synthesis driven by light energy
c.
dephosphorylation of ATP, resulting in a photon of light being released
d.
production of hexose from CO2
e.
none are true
26. Photosynthetic phosphorylation and oxidative phosphorylation are similar processes. All of the
following are common to BOTH processes EXCEPT:
a.
both have fixed and mobile electron carriers.
b.
both contain cytochromes in their electron carrier chains.
c.
both produce NADPH to be used in the reductive pentose phosphate pathway (Calvin
cycle).
d.
both represent a major route of ATP synthesis.
e.
both have quinones as electron carriers.
27. The proton-motive force is composed of a ____ and a ____, and in photophosphorylation the ____ is
greater.
a.
pH gradient; ATP/H+ ratio; ATP/ H+ ratio
b.
ATP/ H+ ratio; ion equilibrium; ion equilibrium
c.
membrane potential; pH gradient; membrane potential
d.
membrane potential; pH gradient; pH gradient
e.
ATP/ H+ ratio; membrane potential; membrane potential
28. Characteristics of the chloroplast’s ATP synthase include all EXCEPT:
a.
contains CF1CF0 complex.
b.
heteromultimer of subunits.
c.
imbedded in the thylakoid membrane.
d.
has 14 c-subunits in its F0 rotor.
e.
all are true.
29. Cyclic photophosphorylation takes place when:
a.
there is not enough light to activate the PSII complex.
b.
NADPH is high, therefore energy is used to drive the citrate cycle.
c.
ferredoxin is used to reduce the Mn-cluster.
d.
the proton gradient is not high enough to go all the way through the system.
e.
NADPH/NADP+ ratio is high, energy is used in generating ATP.
30. All are true for cyclic photophosphorylation EXCEPT:
a.
oxygen is evolved.
b.
utilizes cyt b6 of cyt f/cyt b6 complex.
c.
does not utilize ferredoxin.
d.
PS I is involved.
e.
all are true.
31. Which of the following is an outcome of ferredoxin passing electrons to cytochrome f / cytochrome b6
complex?
a.
proton gradient formation
b.
ATP synthesis
c.
NADPH production
d.
oxygen evolution
e.
both A and B occur
32. Light-dependent electron flow with the production of ATP can occur without the formation of
NADPH. This process is called ____, which involves only one of the photosystems, ____.
a.
noncyclic photophosphorylation; P700
b.
cyclic photophosphorylation; P700
c.
noncyclic photophosphorylation; photosystem II
d.
noncyclic photophosphorylation; P680
e.
cyclic photophosphorylation; P680
33. Which of the following is the product of cyclic photophosphorylation?
a.
NADPH
b.
Molecular oxygen
c.
ATP
d.
ADP and Pi
e.
Electron gradient
34. ____ and ____ are produced in the light reactions of photosynthesis which are used to convert ____ to
____.
a.
ATP; NADPH; carbon dioxide; sugar
b.
oxygen; ATP; NADPH; carbon dioxide
c.
ATP; NADP+; carbon dioxide; sugar
d.
oxygen; NADPH; ATP; sugar
e.
NADPH; ATP; sugar; carbon dioxide
35. Spinach chloroplasts are illuminated in the absence of ADP and Pi, then the light is turned off and
ADP and Pi are added. ATP is then synthesized for a short time in the dark. Which of the following
best explains this?
I.
ATP is generated from the proton gradient accumulated in the light reactions.
II.
ATP synthesis stops after the proton gradient dissipates.
III.
ATP can be generated in the dark reactions if it becomes necessary for the plant to
survive.
a.
I, III
b.
I only
c.
II only
d.
I, II
e.
II, III
36. All are correct statements about rubisco EXCEPT:
a.
ribulose-1,5-bisphosphate and carbon dioxide are both substrates.
b.
the catalytic site has both carboxylase and oxygenase activity.
c.
it is found in the chloroplast stroma.
d.
it releases two molecules of glyceraldehyde-3-phosphate as products.
e.
it may be the most abundant enzyme in plants.
37. The appropriate sequence of events for activation of rubisco is:
A.
carboxylation of E
B.
ribulose-1,5-bisphosphate released from E
C.
rubisco activase
D.
Mg2+ binding
E.
light flash
a.
C, E, D, A, B
b.
C, D, A, B, E
c.
B, C, D, A, E
d.
E, B, C, D, A
e.
E, C, B, A, D
38. Many of the enzymes of the Calvin cycle are also involved in ____; however, the glyceraldehyde-3-
phosphate dehydrogenase of the Calvin cycle is specific for ____.
a.
glycolysis; NADPH
b.
citric acid cycle; NADH
c.
glycolysis; FADH2
d.
citric acid cycle, NADPH
e.
none of the above
39. All are correct about reactions of the Calvin cycle EXCEPT:
a.
ATP is hydrolyzed to ADP.
b.
NADP+ is reduced to NADPH.
c.
an intermediate is fructose-1,6-bisphosphate.
d.
some of the enzymes are shared by glycolysis.
e.
involves a ribulose-5-phosphate kinase.
40. What type of enzyme catalyzes the reaction?
Erythrose-4-P + dihydroxyacetone phosphate (DHAP) sedoheptulose-1,7-bisphosphate
a.
isomerase
b.
aldolase
c.
transaldolase
d.
transketolase
e.
mutase
41. What type of enzyme catalyzes the reaction?
Sedoheptulose-1,7-bisphosphate + H2O sedoheptulose-7-phosphate + Pi
a.
hydrolase
b.
isomerase
c.
aldolase
d.
mutase
e.
lyase
42. What type of enzyme catalyzes the reaction?
sedoheptulose-7-P + glyceraldehyde-3-P xylulose-5-P + ribose-5-P
a.
isomerase
b.
lyase
c.
transaldolase
d.
transketolase
e.
aldolase
43. All of the following are accomplished in the dark reactions of photosynthesis EXCEPT:
a.
carbon dioxide is fixed to ribulose-1,5-bisphosphate.
b.
two molecules of 3-phosphoglycerate are produced.
c.
glyceraldehyde-3-phosphate is used to synthesize glucose.
d.
glyceraldehyde-3-phosphate is used to re-synthesize ribulose-1,5-bisphosphate.
e.
ATP is produced.
44. The reaction, Ribulose-5-phosphate + ATP → Ribulose-1,5-bisphosphate + ADP, is catalyzed by:
a.
phosphopentose isomerase.
b.
phosphoribulose kinase.
c.
ribulose bisphosphate carboxylase.
d.
phosphopentose epimerase.
e.
transketolase.
45. To avoid futile cycling of carbohydrates:
a.
CO2 fixation by Calvin cycle proceeds in the dark.
b.
citric acid cycle, glycolysis and oxidative phosphorylation are inhibited when light is
present.
c.
the enzymes of the Calvin cycle are inhibited by light reactions.
d.
plants do not have glycolytic and citric acid cycle enzymes.
e.
none of the above.
46. The light-induced changes in chloroplasts which regulate key Calvin cycle enzymes include all
EXCEPT:
a.
activation of rubisco activase.
b.
Mg2+ efflux from the thylakoid lumen.
c.
changes in stromal pH.
d.
generation of reducing power.
e.
all are true.
47. Although the ratio of carboxylase to oxygenase activity of rubisco is about ____ to one, the oxygenase
activity diminishes plant productivity because of the loss of ____.
a.
one; rubisco
b.
two; ribulose-5-phosphate
c.
3-4; ribulose-1,5-bisphosphate
d.
6-8; rubisco
e.
8-10; ribulose-5-phosphate
48. How is photorespiration avoided in C-4 plants?
a.
decrease the concentration of phosphoglycolate.
b.
carry carbon dioxide towards an oxygen rich area of the plant.
c.
increase the concentration of ribulose-1,5-bisphosphate.
d.
transport of carbon dioxide from the mesophyll cells to the bundle sheath cells.
e.
none of the above.
49. All of the following are characteristics of a C-4 plant EXCEPT:
a.
PEP carboxylase.
b.
transport of carbon dioxide and reducing power from the mesophyll cells to the bundle
sheath cells.
c.
pyruvate-Pi dikinase.
d.
the expenditure of two high-energy phosphate bonds for each transport of carbon dioxide.
e.
carbon dioxide uptake in the daytime and fixation at night.
50. The essential enzyme in C-4 plants used to conserve CO2 and avoid photophosphorylation is:
a.
rubisco.
b.
PEP carboxylase.
c.
glyceraldehyde-3-phosphate dehydrogenase.
d.
aldolase.
e.
ribulose-5-phosphate kinase.
51. Which of the following set of pathways is similar between plants and animals?
I.
electron transport and the dark reactions of photosynthesis
II.
electron transport and the light reactions of photosynthesis
III.
the Hatch-Slack pathway (C-4) and pyruvate carboxylase
a.
I only
b.
II only
c.
III only
d.
I, III
e.
II, III
52. All of the following are characteristics of CAM plants EXCEPT:
a.
the stroma are open during the night and closed during the day.
b.
they try to avoid loss of water by evaporation.
c.
there is an accumulation of CO2 fixation into the organic acids OAA and malate.
d.
during the night, dicarboxylic acid are stored within the vacuoles.
e.
CO2 is fixed by rubisco during the night.
53. CO2 fixation is one of the most critical reactions on earth. Which of the following are elements of the
reaction catalyzed by the RUBISCO enzyme?
a.
Mg2+ acts as a Lewis acid, binding to CO2 and making it more susceptible to nucleophilic
attack
b.
The 6-carbon enzyme-bound intermediate that forms is split into 2 molecules of 3-
phosphoglycerate
c.
Biotin is attached to a Lys residue in the active site and serves a critical role in the
activation of CO2
d.
ATP is required for the activation of CO2 prior to its reaction with ribulose-1,5-
bisphosphate
e.
Both a and b occur
54. During photosynthesis-linked carbohydrate synthesis in plants, the products of photosynthesis are
required for the actual fixation of carbon. Which of the following correctly explains the use of the
products of photosynthesis?
a.
NADPH is required for the actual reduction of CO2 by the RUBISCO enzyme.
b.
ATP is used primarily during the regeneration of ribulose-1,5-bisphosphate
c.
Oxygen is used during the oxidation of glyceraldehyde-3-phosphate to 1,3-
bisphosphoglycerate
d.
Protons from the formation of the proton gradient are required to activate the RUBISCO
enzyme
e.
Both A and B are correct
55. Which of the following is true regarding CO2 fixation in plants?
a.
CAM plants work by storing carbon dioxide at night in the form of oxaloacetate
b.
The RUBISCO enzyme has a higher affinity for oxygen than for CO2, making it very
difficult to effectively fix CO2
c.
At high temperatures, C4 plants are more efficient than C3 plants because they are able to
fix CO2 with minimal photorespiration
d.
The RUBISCO enzyme contains a Mg2+ that acts as a Lewis base, binding to CO2 and
making it more susceptible to nucleophilic attack
e.
None of the above are true
56. The general flow of electrons in plant photosynthesis is from PSII to PSI. Which of the following
correctly explains the events that occur during this process?
a.
The oxidation of water occurs at PSI with the electrons being passed to ferredoxin to
reduce NADP+.
b.
Protons are pumped into the lumen at PSII during water reduction and also by the
cytochrome bf complex allowing for ATP synthesis to occur.
c.
A cyclic flow of electrons is created between ferredoxin, cytochrome bf complex, and PSI
that allows for the production of NADPH without the generation of ATP.
d.
For each electron removed from a water molecule, 2 photons are required to transfer it to
ferredoxin.
e.
None of the above
57. A new photosystem from a plant with yellow-colored leaves was discovered to have a potential
difference of 2.73 volts between the ground and excited states. What wavelength of light is required to
excite an electron in this photosystem?
a.
228 nm
b.
455 nm
c.
683 nm
d.
910 nm
e.
none of the above