Deck 19: Photosynthesis

Question 1

In the dark reactions of photosynthesis, glyceraldehyde-3-phosphate is converted to dihydroxyacetone phosphate by___.

A)phosphoglucoisomerase
B)triose phosphate isomerase
C)glyceraldehyde-3-phosphate dehydrogenase
D)phosphotriose epimerase
E)phosphoglycerate kinase

Answer 1

triose phosphate isomerase

Question 2

Matching
Choose the correct answer from the list below. Not all the answers will be used.
In the Calvin cycle, ______ is "fixed" to generate carbohydrate molecules.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Answer 2

CO₂

Question 3

Electron transfer in PbRC is approximately ____ efficient.

A)25%.
B)50%.
C)75%.
D)96%.
E)100%.

Answer 3

100%.

Question 4

Matching
Choose the correct answer from the list below. Not all the answers will be used.
______ carries electrons between PSII and PSI.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 5

Which of the following is TRUE regarding the oxygen evolving complex (OEC)?
I.All states have high reduction potentials that exceed that of water.
II.The OEC is made up of magnesium atoms that bridge oxygen atoms together.
III.Current evidence indicates that the OEC cycles between five states in which the metal atoms exist in a variety of combinations of oxidation states.
IV.During the course of reaction, protons and electrons are abstracted from one water molecule yielding one O₂.

A)I, II, III, IV
B)I, III
C)I, II
D)III only
E)III, IV

Question 6

The groups that initially absorb light in the Rps.viridis photosynthetic reaction center are observed to be arranged with ______, and are called the ______.

A)twofold symmetry, special pair
B)anti-parallel symmetry, RHC
C)trifold symmetry, tri-harvest center
D)shared menaquinone prosthetic groups, shared pair
E)none of the above

Question 7

Matching
Choose the correct answer from the list below. Not all the answers will be used.
The electron pathway from water to NADP⁺, referred to as the ____, allows two loci for photochemical events.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 8

An assembly of antenna pigments, or light harvesting complex,

A)are often cytosolic proteins containing multiple chlorophylls.
B)are nearly identical in structure from species to species.
C)are likely optimized to allow efficient transfer of energy throughout pigments.
D)contain an alternating structure of lipid molecules and chlorophylls allowing maximal incorporation in the membrane.
E)none of the above

Question 9

Which statement about carotenoids is FALSE?

A)( $\beta$ -Carotene is an example of a common accessory pigment..)
B)Carotenoids are often used ensure complete coverage of the spectrum.
C)Carotenoids are contained in the prosthetic ring structure of chlorophylls.
D)( $\beta$ -Carotene aides in light absorption for photosynthesis..)
E)All of the above statements are true.

Question 10

Matching
Choose the correct answer from the list below. Not all the answers will be used.
The light reactions of photosynthesis occur in the _____ membrane of the chloroplast.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 11

The photosynthetic electron transport system includes the transmembrane complexes PSI, PSII and

A)PSIII.
B)cytochrome a₃.
C)cytochrome b₆f.
D)cytochrome c.
E)proton translocating ATP synthase

Question 12

Matching
Choose the correct answer from the list below. Not all the answers will be used.
Light-harvesting antennas gather photons and pass the energy to the ______ .

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 13

Synthesis of sucrose requires which of the following?
I.glyceraldehyde-3-phosphate and/or dihydroxyacetone phosphate
II.sucrose phosphate kinase
III.sucrose phosphate phosphatase
IV.UTP

A)I, II, III, IV
B)I, II, IV
C)I, III, IV
D)II, III
E)II, III, IV

Question 14

Matching
Choose the correct answer from the list below. Not all the answers will be used.
PSII oxidizes ____.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 15

Matching
Choose the correct answer from the list below. Not all the answers will be used.
Electron transport through the cytochrome b₆f complex generates a _____ gradient.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 16

Matching
Choose the correct answer from the list below. Not all the answers will be used.
The most abundant biological catalyst is ______.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 17

Light dependent ATP synthesis is called

A)photophosphorylation.
B)substrate-level phosphorylation.
C)oxidative phosphorylation.
D)pyrophosphorylation.
E)none of the above

Question 18

Which of the following is the site of ATP synthesis in chloroplasts?

A)smooth outer membrane
B)inner membrane space
C)stroma
D)thylakoid membrane
E)thylakoid compartment

Question 19

Matching
Choose the correct answer from the list below. Not all the answers will be used.
The chloroplast ATP synthase is also called ______.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 20

Matching
Choose the correct answer from the list below. Not all the answers will be used.
The electrons abstracted by the oxygen evolving center (OEC)are relayed to a ______.

A)photosynthetic reaction center
B)tyrosyl radical
C)thylakoid
D)H₂O
E)CF₁CF₀
F)Z-scheme
G)NADPH
H)plastoquinone
I)H+
J)RuBP carboxylase
K)CO₂
L)2 OH–
M)O₂

Question 21

Based on comparison of oxidative phosphorylation to photophosphoylation, which of the following is TRUE?

A)Photophosphoylation cannot be uncoupled by an ionophore like can be done with oxidative phosphorylation.
B)The formation of a proton gradient is required for adequate function of both photo- and oxidative phosphorylation.
C)Although sequence similarities exist between the ATP synthases from each process, little structural similarity is observed.
D)Photophosphorylation is not dependent on spontaneous electron flow whereas oxidative phosphorylation requires that electron flow be spontaneous.
E)None of the above is true.

Question 22

Which of the following is(are)FALSE about photorespiration?

A)RuBP carboxylase oxygenates ribulose bisphosphate to form 2-phosphoglycolate and 3-phosphoglycerate.
B)The reaction provides an additional mechanism to generate ATP and NADPH.
C)The C₄ cycle minimizes the need for photorespiration.
D)CO₂ and O₂ compete for binding the RuBP carboxylase active site.
E)Photorespiration is thought to function as a protective mechanism to allow dissipation of unused energy.

Question 23

Which of the following correctly identifies the products and amounts produced from noncyclic electron transport?

A)4 ATP per O₂ plus 2 NADPH per 4 electrons liberated from 2 H₂O
B)5 ATP per O₂ plus 1 NADPH per 4 electrons liberated from 2 H₂O
C)2.5 ATP per O₂ plus 2 NADPH per 2 electrons liberated from 2 H₂O
D)9 ATP per O₂ plus 2 NADPH per 4 electrons liberated from 2 H₂O
E)5 ATP equivalents

Question 24

The major difference between pheophytins and chlorophylls is

A)pheophytins contain iron in their centers while chlorophylls contain magnesium.
B)chlorophylls contain iron in their centers while pheophytins contain magnesium.
C)pheophytins contain no metal ion in their centers.
D)pheophytins are linear, rather than cyclic tetrapyrroles.
E)none of the above

Question 25

The oxygen evolving center
I.is a part of PSI known as the water splitting enzyme.
II.breaks two H₂O molecules into four protons, four electrons and O₂.
III.requires four light-dependent reactions to generate O₂.
IV.frees an electron from oxygen for replacement of the photooxidized electron in P680.

A)I, II, III, IV
B)I, II
C)II, III, IV
D)II, III
E)I, IV

Question 26

Which of the following statements concerning Z-scheme photosynthesis is TRUE?

A)Water is reduced by a Mn-containing cluster.
B)Electrons are carried by lipid-soluble plastoquinones, which participate in a Q cycle.
C)Ferredoxin oxidizes NADPH.
D)Transfer occurs stepwise from PSI to PSII with increasing potential.
E)A proton gradient is not generated to drive ATP synthesis.

Question 27

Which of the following statements about photosynthetic pigments is FALSE?

A)Carotenoid pigments absorb light in the 400-500 nm range
B)Chlorophylls a and b absorb both long and short wavelength light
C)Phycoerythrin absorbs blue and green light.
D)Phycocyanin absorbs yellow light around the 600 nm range
E)Bacteriochlorophyll a overlaps the absorption wavelengths of chlorophylls a and b

Question 28

Binding of oxygen to RuBisCo

A)destroys enzymatic function because oxygen is a suicide inhibitor of the enzyme.
B)targets the enzyme for proteolytic degradation.
C)decreases the enzyme's K_m for oxygen since binding is cooperative.
D)activates the enzyme for carbon fixing reactions.
E)costs the cell ATP since energy is required to replace intermediates necessary for carbon fixation.

Question 29

Which of the following are possible functions for the activated electrons from PSI?
I.reduction of NAD⁺
II.reduction of NADP⁺
III.formation of ATP
IV.formation of a proton gradient
V.formation of an ionic gradient

A)I, II
B)I, III
C)II, III
D)II, IV
E)I, V

Question 30

It is believed that the ratio of cyclic photophosphorylation to Z-scheme photosynthesis changes in response to metabolic demands.How would this ratio in chloroplasts performing the following reaction compare to that in chloroplasts performing only the Calvin cycle? Calvin cycle + reduction of nitrite (NO₂^-)to NH₃

A)The ratio of cyclic photophosphotylation to Z-scheme is increased in chloroplasts performing the above reaction compared to those performing only the Calvin cycle
B)The ratio of cyclic photophosphotylation to Z-scheme is decreased in chloroplasts performing the above reaction compared to those performing only the Calvin cycle
C)The ratio of cyclic photophosphotylation to Z-scheme is depends primarily on the level of light available and would therefore not be altered by the above reaction
D)The ratio of cyclic photophosphotylation to Z-scheme is depends primarily on the availability of plastocyanin and would therefore not be altered by the above reaction
E)none of the above

Question 31

A houseplant is treated with a compound that inactivates plastocyanin.Which of following might allow the plant to survive?

A)supplement with light with a wavelength of 680 nm or less
B)supplement with light with a wavelength greater than 680 nm
C)addition of an uncoupling agent thus allowing ATP synthesis to resume
D)addition of an oxidant capable of oxidizing NADPH, thus decreasing photorespiration.
E)none of the above

Question 32

A radioactive labeled carbon entering the Calvin cycle as ¹⁴CO₂

A)would be removed from the cycle as various carbohydrate side products in the first round of the cycle.
B)could be identified only in the triose intermediates within the cycle.
C)would only be observed in intermediates following three rounds of the cycle.
D)could be observed in any of the intermediates within the cycle during the first or subsequent rounds of the cycle.
E)would be rapidly removed by transketolase catalyzed reactions.

Question 33

Which of the following statements concerning crassulacean acid metabolism (CAM)is TRUE?

A)It allows desert plants to collect CO₂ at night for use during the day in the Calvin cycle.
B)Desert plants utilize CAM to transport CO₂ to bundle sheath cells where the Calvin cycle takes place.
C)It permanently fixes CO₂ in place of RuBisCo, avoiding the oxygenase reaction.
D)CAM facilitates transport of photorespiration products back to the Calvin cycle.
E)All of the above are true.

Question 34

Which of the following statements about the OEC is FALSE?
I.It is located at the lumenal surface of the D1 subunit
II.It has a low reduction potential in all states
III.It contains Mn₄CaO₄ or Mn₄CaO₅
IV.Part of the cluster is liganded to the amino acids Asp and Glu

A)II, III
B)II only
C)III only
D)II, IV
E)II, III

Question 35

In plants and cyanobacteria, PSII ______, and PSI ______.

A)oxidizes H₂O, reduces NAD⁺
B)oxidizes H₂O, reduces NADP⁺
C)oxidizes O₂, reduces FAD
D)oxidizes H₂O, reduces FAD
E)none of the above are true

Question 36

The major sugar transported to nonphotosynthesizing cells is

A)sucrose.
B)fructose.
C)UDP-glucose.
D)fructose-6-phosphate.
E)glyceraldehyde-3-phosphate.

Question 37

Which of the following statements concerning cyclic photophosphorylation is FALSE?

A)Only PSI is used.
B)Plastocyanin is oxidized by the photosystem.
C)NADPH donates electrons to the plastoquinone pool.
D)Ferredoxin accepts electrons from the photosystem and reduces the cytochrome bf complex.
E)This system is used to pump protons and form an electrochemical gradient to drive the formation of ATP.

Question 38

Which mechanism is the method by which antenna complex chlorophylls funneled energy toward the reaction centers?

A)fluorescence
B)internal conversion
C)resonance energy transfer (exciton transfer)
D)electron transfer
E)none of the above

Question 39

Which of the following would decrease the activity of RuBP carboxylase?
I.a change in the pH of the stroma from 6.7 to 7.9
II.an increase in the concentration of Mn²⁺ in the stroma
III.an uncoupling protein embedded in the thylakoid membrane
IV.presence of the transition state analog CA1P

A)I, II, III, IV
B)I, III, IV
C)II, III, IV
D)III, IV
E)I, III

Question 40

A houseplant has been mutated so that its chlorophyll is more efficient at fluorescence than normal.What will be the likely result?

A)Both forms of the light reactions will improve and the plant will better tolerate low light conditions.
B)Z-scheme photosynthesis will be favored over cyclic photophosphorylation, making additional illumination at long wavelengths necessary.
C)Cyclic photophosphorylation will be favored over Z-scheme, making additional illumination at short wavelengths necessary.
D)√Both forms of the light reaction will be impaired and the plant will be less tolerant to low light conditions.
E)none of the above

Question 41

In photorespiration, reduction of hydroxypyruvate to glycerate requires ____ and occurs in the ____.

A)NADPH; mitochondrion
B)NADH; peroxisome
C)NADPH; chloroplast
D)NADH; chloroplast
E)none of the above

Question 42

Which of the following is a product of the Calvin cycle?
I.ATP
II.Glyceraldehyde-3-phosphate
III.NADPH
IV.CO₂

A)I only
B)I, III
C)II only
D)II, IV
E)I, III, IV

Question 43

Electrons from FB in PSI that follow the cyclic pathways are returned from ____ via ____ to the plastoquinone pool.

A)plastocyanin; plastoquinone
B)PSI; cytochrome b₆
C)PSI; plastoquinone
D)plastocyanin; cytochrome b₆
E)cytochrome b₆; plastoquinone

Question 44

Electrons abstracted from water by ___ are relayed to ___ via formation of a ____.

A)OEC; P680⁺; plastoquinone
B)PSII; cytochrome b₆; plastoquinone
C)OEC; P680⁺; tyrosyl radical
D)OEC; cytochrome b₆; tyrosyl radical
E)OEC; P960⁺; tyrosyl radical

Question 45

Light activation of P680 results in which of the following?
I.electron transfer as follows: Q_A $\rarr$ Q_B $\rarr$ Chlα $\rarr$ Pheoα
II.electron transfer from PSI directly back to the Pheoα-Q_A complex
III.reduction of S₄ of the OEC to S₁ of the OEC
IV.reduction of cytochrome b₆f

A)I, III, IV
B)I, II
C)II, III
D)I only
E)IV only

Question 46

The protein which passes electrons to NADP⁺ thus forming the NADPH generated from noncyclic electron transport is

A)ferridoxin-NADP⁺ reductase.
B)ferridoxin NADPH dehydrogenase.
C)ferridoxin FAD dehydrogenase.
D)FAD reductase.
E)FAD dehydrogenase.

Question 47

The redox centers PSII, PbRC, PbRC from Rps.viridis, and cytochrome b₆f

A)have identical prosthetic groups that differ only in sequence of arrangement and spatial orientation.
B)have some degree of symmetry either based on their prosthetic groups or based on tertiary protein structure.
C)all become reduced due to activity of the OEC.
D)all of the above
E)none of the above

Question 48

Which of the following correctly represents the Q cycle? (Note: Portions are omitted for simplicity)

A)

B)

C)

D)

E)

Question 49

Which of the following is TRUE regarding the difference between chlorophyll structures and heme?

A)Chlorophyll structures contain copper rather than iron.
B)Chlorophyll structures typically have five rings while heme typically has four.
C)Chlorophyll often has fewer R groups attached to the ring system that heme.
D)Chlorophyll metal atoms coordinate to the nitrogen atoms from the ring where as heme iron atoms coordinate to carbon atoms.
E)all of the above

Question 50

Synthesis of starch requires
I.ATP
II.glucose-1-phosphate
III.ADP-glucose phosphatase
IV.ADP-glucose

A)I, II, III
B)II, III, IV
C)I, III, IV
D)I, II, IV
E)II, III