Deck 20: Photosynthesis

Question 1

Which of the following represents the molecules of A and B in the reaction sequence below?
Chl + hv à Chl*
Chl* + A à Chl.⁺ + A-
Chl)⁺ + A- à Chl.⁺ + B⁺

A)chlorophyll
B)electron-transfer
C)proton-donor
D)CO₂

Answer 1

B

Question 2

Which of the following are the primary roles of carotenoids in photosynthesis?

A)accessory light harvesting and photo-oxidation
B)resonance transfer pigments and photo-oxidation
C)accessory light harvesting and photoprotection from reactive oxygen species
D)resonance transfer and photodiffusion protection

Answer 2

C

Question 3

Which of the following structures is formed in chloroplasts when the thylakoid membrane is organized into paired folds?

A)stroma
B)lamellae
C)porin
D)calcium channel

Answer 3

B

Question 4

In which of the following organelles does photosynthesis take place?

A)chloroplasts
B)ribosomes
C)membranes
D)photoplasts

Question 5

Which of the following products is generated when light energy is transduced into chemical energy during photosynthesis?

A)CO₂
B)hexose
C)acetyl CoA
D)NADP+

Question 6

Which of the following is NOT involved in the production of biochemical energy from light?

A)electron transfer
B)Q cycle
C)transmembrane pH gradient
D)ribulose-1-phosphate phosphorylation

Question 7

Which of the following is a property of both the P700 and the P680 reaction centres?

A)involved in light-driven O₂ evolution
B)contain chlorophyll monomers
C)electron acceptors
D)activated by visible light

Question 8

Which of the following is NOT a property of photosystem II (PSII)?

A)light-driven H₂O evolution
B)similar photosystem in photosynthetic bacteria
C)uses quinines as terminal electron acceptors
D)found in cyanobacteria,green algae,and higher plants

Question 9

Which of the following is NOT contained in chloroplasts?

A)thylakoid membrane
B)ribosomes
C)DNA and RNA
D)calcium channels

Question 10

Which of the following best explains the involvement of light reactions in photosynthetic plants?

A)discharge of the proton gradient
B)production of ATP and consumption of NADPH
C)production of ATP and NADPH during cyclic photophosphorylation
D)the splitting of 2 water molecules to produce molecular oxygen

Question 11

In which of the following parts of the chloroplast is chlorophyll located?

A)thylakoid membranes associated with proteins
B)thylakoid spaces associated with rubisco
C)inner membrane space
D)outer membrane

Question 12

Many chlorophyll molecules absorb light and direct the energy to the reactive centres.Which of the following describes the term for the transfer of this absorbed energy?

A)fluorescence transfer
B)resonance energy transfer
C)photochemical emission
D)energy transduction

Question 13

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.Which of the following terms describes this type of reaction?

A)isomerise
B)mutase
C)ligase
D)oxidation-reduction

Question 14

Which of the following statements regarding the light reactions of photosynthesis is correct?

A)There are 2 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)Plastoquinone is a fixed electron transporter in the system located in the inner membrane.

Question 15

In light reactions,which of the following is the reducing agent and the ultimate oxidizing agent respectively?

A)NADP⁺ and NADPH
B)ADP and ATP
C)H?O and NADP⁺
D)NADPH and NADP⁺

Question 16

How many CO₂ molecules (X)are required to balance this reaction?
12 NADPH + 12 H⁺ + 18 ATP + X CO₂ + 12 H₂O à C₆H₁₂O₆ + 12 NADP⁺ + 18 ADP + 18 Pᵢ

A)3
B)6
C)12
D)18

Question 17

Which of the following is NOT a characteristic of chlorophyll?

A)iron-containing porphyrin
B)planar conjugated porphyrin ring
C)delocalized p electrons in the aromatic ring
D)photoexcitable electrons

Question 18

Which of the following is the photochemical event that is the essence of photosynthesis?

A)conversion of H₂O to O₂
B)phosphorylation of ADP
C)light energy transduction to chemical energy
D)fixation of CO₂

Question 19

Which of the following is NOT involved with the function of the photosynthetic unit ?

A)antenna chlorophyll
B)the reactive centre
C)oxidation of chlorophyll to a cationic free radical,Chl.+
D)the cationic free radical is the Mg²⁺ ion

Question 20

Which of the following explains how chloroplasts differ from mitochondria?

A)Chloroplasts cannot 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.

Question 21

Which of the following is an outcome of ferredoxin passing electrons to cytochrome f / cytochrome b₆ complex?

A)NADH reduction
B)cyclic flow of protons
C)proton gradient dissipation
D)ATP synthesis

Question 22

Which of the following is a characteristic of the chloroplast's ATP synthase?

A)is a homomultimer of subunits
B)contains CF1CF0 complex
C)embedded in the plasma membrane
D)has 12 c-subunits in its F0 rotor

Question 23

Which of the following enzymes catalyzes the reaction below?
Erythrose-4-P + dihydroxyacetone phosphate (DHAP)Û sedoheptulose-1,7-bisphosphate

A)aldolase
B)transaldolase
C)transketolase
D)mutase

Question 24

Which of the following describes when does cyclic photophosphorylation take place?

A)when the NADPH/ NADP+ ratio is high and energy is used in generating ATP
B)when NADPH is high and therefore energy is used to drive the citrate cycle
C)when ferredoxin is used to reduce the Mn cluster
D)when the proton gradient is not high enough to go all the way through the system

Question 25

Which of the following statements regarding light is correct?

A)The energy of a photon of light is calculated by E = hn.
B)The energy of 700 nm light is greater than that of 400 nm light.
C)Photosynthesis allows 2 electrons to flow for each pair of photons absorbed per centre.
D)The quantum yield of photosynthesis can be described as CO₂ fixed per photon absorbed,or O₂ evolved per photon absorbed.

Question 26

Photosynthetic phosphorylation and oxidative phosphorylation are similar processes.Which of the following is common to both processes?

A)Both produce NADPH to be used in the reductive pentose phosphate pathway (Calvin cycle).
B)Both contain cytochromes in their electron carrier chains.
C)Both represent a major route of ATP hydrolysis.
D)Both have iron clusters as electron carriers.

Question 27

Which of the following components are produced in the light reactions of photosynthesis and are used to convert carbon dioxide to sugar?

A)ATP and NADPH
B)water and ATP
C)ATP and NADP⁺
D)light and ATP

Question 28

Light-dependent electron flow with the production of ATP can occur without the formation of NADPH.Which of the following photosystems is involved in this cyclic photophosphorylation?

A)P700
B)photosystem II
C)P680
D)ferredoxin

Question 29

Which of the following is NOT a feature of cyclic photophosphorylation?

A)Oxygen is evolved.
B)It utilizes cyt b6 of cyt f / cyt b6 complex.
C)It does not utilize ferredoxin.
D)PS I is involved.

Question 30

Which of the following is the product(s)of the R.viridis photosynthetic reaction centre?

A)mobile reduced quinone
B)NADPH
C)reduced ferredoxin
D)protons

Question 31

Many of the enzymes of the Calvin cycle are also involved in glycolysis and the pentose phosphate pathway.Which of the following molecules is specific for the glyceraldehyde-3-phosphate dehydrogenase of the Calvin cycle?

A)NADPH
B)NADH
C)FADH₂
D)FAD

Question 32

Which of the following is the product of cyclic photophosphorylation?

A)NADPH
B)molecular oxygen
C)ATP
D)electron gradient

Question 33

Where do electrons from water ultimately flow to,via PSI and PSII?

A)NAPDH
B)NADP⁺
C)NAD?
D)NADH

Question 34

Which of the following regarding the reactions of the Calvin cycle is correct?

A)ADP is phosphorylated to ATP.
B)It involves a ribulose-5-phosphate kinase.
C)NADP+ is reduced to NADPH.
D)An intermediate is fructose-6-bisphosphate.

Question 35

Which of the following two components constitute the proton-motive force?

A)an ATP/H⁺ ratio and an ion equilibrium
B)pH gradient and an ATP/H⁺ ratio
C)a membrane potential and a pH gradient
D)an ATP/H⁺ ratio and a membrane potential

Question 36

Which of the following terms defines photophosphorylation?

A)activation of enzymes with light
B)dephosphorylation of ATP,resulting in a photon of light being released
C)ATP synthesis driven by light energy
D)production of hexose from CO₂

Question 37

Which of the following does NOT contribute to the activation of rubisco?

A)carboxylation of E
B)ribulose-1,5-bisphosphate released from E
C)rubisco activase
D)ZN₂+ binding

Question 38

Which of the following statements regarding the enzyme rubisco is correct?

A)It releases 2 molecules of glyceraldehyde-3-phosphate as products.
B)Ribulose-1,5-bisphosphate is the substrate and carbon dioxide is the product.
C)Its catalytic site has both carboxylase and oxygenase activity.
D)It is the least abundant enzyme in plants.

Question 39

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?

A)ATP is generated from the electron gradient accumulated in the light reactions.
B)ATP synthesis stops after the proton gradient dissipates.
C)ATP can be generated in the dark reactions if it becomes necessary for the plant to survive.
D)ATP synthesis can occur in the absence of light and electrons.

Question 40

Which of the following is the equivalent of product formed,as defined by the quantum yield of photosynthesis?

A)photons
B)coenzyme Q
C)light input
D)carbohydrate

Question 41

Which of the following factors assists in avoiding futile cycling of carbohydrates?

A)CO₂ fixation by Calvin cycle procession in the dark
B)citric acid cycle,glycolysis,and oxidative phosphorylation inactivation during the light
C)inhibition of the enzymes of the Calvin cycle by light reactions
D)the absence of glycolytic and citric acid cycle enzymes in plants

Question 42

Which of the following describes how photorespiration avoided in C-4 plants?

A)decreased concentration of phosphoglycolate
B)carbon dioxide carried toward an oxygen-rich area of the plant
C)increased concentration of ribulose-1,5-bisphosphate
D)carbon dioxide transportation from the mesophyll cells to the bundle sheath cells

Question 43

Which of the following sets of pathways is similar between plants and animals?

A)electron transport and the dark reactions of photosynthesis
B)electron transport and pyruvate carboxylase
C)the Hatch-Slack pathway (C-4)and pyruvate carboxylase
D)the Hatch-Slack pathway (C-4)and the dark reactions of photosynthesis

Question 44

Which of the following is NOT a characteristic of a C-4 plant?

A)transport of carbon dioxide and reducing power from the mesophyll cells to the bundle sheath cells
B)pyruvate-Pi dikinase
C)expenditure of 2 high-energy phosphate bonds for each transport of carbon dioxide
D)carbon dioxide uptake in the daytime and fixation at night

Question 45

Which of the following enzymes catalyzes the reaction below?
Sedoheptulose-1,7-bisphosphate + H₂O Û sedoheptulose-7-phosphate + Pᵢ

A)hydrolase
B)isomerase
C)aldolase
D)mutase

Question 46

Which of the following activities does NOT occur during the light-induced changes in chloroplasts?

A)activation of rubisco activase
B)Mg²⁺ efflux from the thylakoid lumen
C)changes in stromal pH
D)generation of oxidizing power

Question 47

Which of the following essential enzymes in C-4 plants is used to conserve CO₂ and avoid photophosphorylation?

A)rubisco
B)PEP carboxylase
C)aldolase
D)ribulose-5-phosphate kinase

Question 48

Which of the following is a characteristic of CAM plants?

A)CO₂ is fixed by rubisco during the night.
B)The stomata are closed during the night and open during the day.
C)They try to avoid loss of water by condensation.
D)During the night,dicarboxylic acid is stored within the vacuoles.

Question 49

Which of the following enzymes catalyzes the reaction below?
Ribulose-5-phosphate + ATP à ribulose-1,5-bisphosphate + ADP

A)phosphopentose isomerase
B)phosphoribulose kinase
C)ribulose bisphosphate carboxylase
D)phosphopentose epimerase

Question 50

Which of the following is NOT accomplished in the dark reactions of photosynthesis?

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)ATP is produced.

Question 51

Which of the following enzymes catalyzes the reaction below?
Sedoheptulose-7-P + glyceraldehyde-3-P Û xylulose-5-P + ribose-5-P

A)isomerase
B)transaldolase
C)transketolase
D)aldolase

Question 52

Which of the following is the ratio of carboxylase to oxygenase activity of rubisco?

A)1 to 1
B)2 to 1
C)3-4 to 1
D)6-8 to 1