Chapter 10 Flashcards
Plants are green because
A. chlorophylls absorb blue and orange-red wavelengths of light and reflect green light.
B. chloroplasts capture energy of green photons for photosynthesis.
C. energized chlorophyll a emits green light.
D. plants only have green pigments.
E. chlorophyll molecules absorb green light for photosynthesis.
A
Photosynthesis and respiration have which of the following in common?
A. In eukaryotes, both processes reside in specialized organelles.
B. ATP synthesis in both processes relies on the chemiosmotic mechanism.
C. Both use electron transport.
D. Both require light.
E. a, b, and c
E
The Calvin cycle uses ___ to produce carbohydrate.
A. CO2
B. ATP
C. NADPH
D. rubisco
E. All of the above
E
Which of the following statements is false concerning photosynthesis?
A. Photosynthesis is an andergonic process.
B. Photosynthesis converts light energy to chemical energy.
C. Photosynthesis involves electron transport through two electron transport chains.
D. Photosynthesis is exactly cellular (aerobic) respiration in reverse.
E. Photosynthesis is an anabolic process.
D
Which of the following is the revised, balanced equation for photosynthesis?
A. 6 CO2 + 6 H2O –> C6H12O6 + O2
B. 6 CO2 + 12 H2O –> C6H12O6 + 6 O2 + 6 H2O
C. 6 CO2 + 6 H2O –> C6H12O6 + 6 O2
D. 12 CO2 + 12 H2O –> 2 C6H12O6 + 2 O2
E. None of the above
B
The precise moment when light energy is captured in chemical energy is the point at which
A. light shines on chlorophyll.
B. water is hydrolyzed.
C. chlorophyll is oxidized.
D. chlorophyll is reduced.
E. the CO2 from air is captured in a sugar.
C
The first phase of photosynthesis, a series of reactions that requires the absorption of photos to form ATP and NADPH, is referred to as the ___ phase.
A. reduction
B. dark reactions
C. carbon fixations
D. light reactions (or photophosphorylation)
E. None of the above
D
In photosynthesis, light energy is sued to extract hydrogen atoms from ___ and ultimately transfer therm to ___.
A. glucose; water
B. chlorophyll; glucose
C.water; CO2
D. water; oxygen
E. None fo the above
C
Which of the following occurs during the light-independent reactions of photosynthesis?
A. Water is split into hydrogen and oxygen.
B. CO2 is ocnverted into sugars.
C. Chlorophyll is oxidized.
D. ATP is synthesized.
E. All of the above
B
The O2 gas produced during photosynthesis is derived from
A. CO2.
B. glucose.
C. water.
D. CO.
E. bicarbonate ions.
C
The Calvin cycle results int eh production of
A. glucose.
B. starch.
C. rubisco.
D. G3P.
E. ATP.
D
In plant cells, the electron transport chains of photosynthesis
A. are located in the thylakoid membranes ot the chloroplasts.
B. are located int eh stroma of the chloroplasts.
C. are located in the cristae of the mitochondria.
D. hydrolyze ATP rather than synthesize it.
E. are directly involved in sugar synthesis.
A
In noncyclic photosynthetic electron transport, water is used to
A. excite chlorophyll.
B. hydrolyze ATP.
C. reduce Pi.
D. oxidize NADPH.
E. reduce chlorophyll.
E
Which statement about light is true?
A. An absorption spectrum is a plot of biological effectiveness versus wavelength.
B. An absorption spectrum may be a good means of identifying a pigment.
C. Light need not be absorbed to produce a biological effect.
D. A given kind of molecule can occupy any energy level.
E. A pigment loses energy as it absorbs a photon.
B
Which statement about chlorophylls is not true?
A. Chlorophylls absorb light near both ends of the visible spectrum.
B. Chlorophylls can accept energy from other pigments, such as carotenoids.
C. Excited chlorophyll can either reduce another substance or release light energy.
D. Excited chlorophyll cannot be an oxidizing agent.
E. Chlorophylls contain magnesium.
D
In cyclic electron transport,
A. oxygen gas is released.
B. ATP is formed.
C. water donates electrons and protons.
D. NADPH forms.
E. CO2 reacts with RuBP.
B
Which of the following does not happen in noncyclic electron transport?
A. Oxygen gas is released.
B. ATP forms.
C. Water donates electrons and protons.
D. NADPH forms.
E. CO2 reacts with RuBP.
E
In chloroplasts,
A. light leads to the flow of protons out of the thylakoids.
B. ATP is formed when protons flow into the thylakoid lumen.
C. light causes the thylakoid lumen to become less acidic than the stroma.
D. protons return passively to the stroma through protein channels.
E. proton pumping requires ATP.
D
Which statement about the Calvin cycle is not true?
A. CO2 reacts with RuBP to form 3PG.
B. RuBP forms by the metabolism of 3PG.
C. ATP and NADPH form when 3PG is oxidized.
D. The concentration of 3PG rises if the light is switched off.
E. Rubisco catalyzes the reaction of CO2 and RuBP.
D
In C4 photosynthesis,
A. 3PG is the first product of CO2 fixation.
B. rubisco catalyzes the first step in the pathway.
C. 4-carbon acids are formed by PEP carboxylase in bundle sheath cells.
D. photosynthesis continues at lower CO2 levels than in C3 plants.
E. CO2 released from RuBP is transferred to PEP.
D
Photosynthesis in green plants occurs only during the day. Respiration in plants occurs
A. only at night.
B. only when there is enough ATP.
C. only during the day.
D. all the time.
E. in the chloroplast after photosynthesis.
D
Photorespiration
A. takes place only in C4 plants.
B. includes reactions carried out in peroxisomes.
C. increases the yield of photosynthesis.
D. is catalyzed by PEP carboxylase.
E. is independent of light intensity.
B
Which of the following statements about photosynthesis is false?
A. The light-independent reactions occur in the dark.
B. The Calvin cycle takes place in the stroma.
C. Oxygen is produced by thylakoid membranes.
D. ATP and NADPH link the light reactions and the light-independent reactions.
E. CO2 is reduced to sugars.
A
Which of the following statements regarding light absorption and photosynthesis is false?
A. Red and blue light are effective in driving photosynthesis.
B. Chlorophyll appears green because it absorbs green light.
C. Light energy absorbed by chlorophyll may be transferred to a neighboring molecule.
D. The action spectrum for photosynthesis resembles the absorption spectrum of chlorophyll.
E. Absorption of a photon can boost a molecule to an excited, higher energy state.
B
Which statement about a photosystem is false?
A. Only the reaction center chlorophyll becomes oxidized in the light.
B. The majority of pigment molecules serve as antennae or light harvesting molecules.
C. Most of the light absorbed is re-emitted as fluorescence.
D. Chemical work is done.
E. Energy transfer among pigments takes place.
C
Which of the following statements about the activities of photosystems I and II is false?
A. Water is oxidized by photosystem II.
B. Photons are required to drive both photosystems.
C. The reaction center chlorophylls differ in the two photosystems.
D. Sustained, noncyclic ATP production requires the activities of both photosystem I and photosystem II.
E. The reduction of NADP+ to NADPH is carried out by photosystem II.
E
Which of the following statements related to electron transport in photosynthesis is true?
A. Water is a strong reducing agent.
B. Reaction center chlorophylls are not part of the electron transport chain.
C. NADPH is a weak reducing agent.
D. Non-cyclic electron transport may be represented as: H2O + NADP+ → ½ O2 + NADPH + H+.
E. Non-cyclic electron transport is not coupled to ATP synthesis.
D
Which of the following statements correctly describes cyclic electron transport? (See figure.)
A. Cyclic electron transport requires both photosystems I and II.
B. Cyclic electron transport produces NADPH.
C. Cyclic electron transport involves photosystem I, ferredoxin, and the electron transport chain between the two photosystems.
D. There is a net oxidation of P700 during cyclic electron transport.
E. There is no product of cyclic electron transport.
C
Based on the figure here, which of the following partial reactions of the chloroplast electron transport chain would generate a proton-motive force in the light?
A. H2O to PQ
B. : PC to Fd
C. Fd to NADP+
D. PQ to PC
E. A and D
E
Which of the following statements about the Calvin cycle (see figure) is false?
A. The reactions of the Calvin cycle cease shortly after the light is switched off.
B. Carbon dioxide fixation produces a compound called 3-phosphoglycerate (3PG).
C. Ribulose bisphosphate (RuBP) reacts with CO2.
D. CO2 reduction requires ATP and NADPH.
E. 3-Phosphoglycerate is a phosphorylated sugar.
E
This statement is false. 3PG is a carboxylic acid. The COOH group of 3PG is reduced by NADPH to an aldehyde group. The resulting compound, glyceraldehyde 3-phosphate, is a phosphorylated sugar.
Photorespiration
A. consumes CO2 and releases O2.
B. occurs in all green plants.
C. is initiated by the oxygenation of RuBP.
D. is most rapid when the ratio of CO2 to O2 in chloroplasts is high.
E. occurs in the dark.
C
The accompanying figure shows the arrangement of cells in the leaves of a C3 plant and of a C4 plant. Which of the following is not a difference between C3 and C4 plants?
A. The bundle sheath cells of C4 plants have rubisco, whereas bundle sheath cells in the C3 plant have little rubisco.
B. The first product of photosynthesis in C3 plants is a 3-carbon molecule (3PG).
C. C4 plants have two enzymes for carbon fixation, whereas C3 plants have only one.
D. Photosynthesis in C3 plants occurs in the mesophyll.
E. C3 plants have high rates of photorespiration.
D
This figure shows two cells from a C4 plant. Select the answer that correctly completes this sentence: The lower cell in this figure is characterized by a _______ carbon fixation pathway, a _______ CO2/O2 ratio in the cell, and the major carbon fixation enzyme is _______.
A. C3; Low; Rubisco
B. C3; High; Rubisco
C. C3 and C4; High; Rubisco
D. C3 and C4; High; PEP Carboxylase
E. C4; Low; PEP Carboxylase
C
Which of the following statements about the Calvin cycle and cellular respiration is false?
A. The carbohydrates synthesized in the dark reactions are used to fuel cellular respiration.
B. Both cellular respiration and fermentation can occur in plants.
C. G3P produced in the Calvin cycle can be converted to pyruvate.
D. Cellular respiration in leaves occurs only at night
E. Most of the G3P from the Calvin cycle can be used for sucrose synthesis in the cytoplasm.
D
Plants that carry out crassulacean acid metabolism (CAM) differ from C4 plants in that
A. CAM plants do not contain PEP carboxylase.
B. CAM plants open their stomata only at night.
C. the first product of CO2 fixation in CAM plants is 3PG.
D. CAM plants are adapted to wet environments.
E. CAM plants have high rates of photorespiration.
B
The Calvin cycle maybe divided into three phases: CO2 fixation (A), Reduction (B), and Regeneration of RuBP (C). Per CO2 fixed, how many molecules of ATP are used in each phase of the cycle?
A. A–0, B–1, C–2
B. A–0, B–2, C–1
C. A–1, B–1, C–1
D. A–0, B–1, C–1
E. A–0, B–3, C–0
B
Which statement about activation of the Calvin cycle in the light is false?
A. NADPH is the source of electrons for the reduction of disulfide bond to dithiols.
B. Four enzymes of the cycle are reduced in the light.
C. Reduced ferredoxin reduces thioredoxin.
D. Reduced thioredoxin reduces disulfide bonds in the enzymes.
E. The reduced enzymes are more active than the oxidized enzymes.
A
Calvin cycle
stage in photosynthesis in which CO2 reacts with RuBP to form 3PG, which is then reduced to a sugar, and RuBP is regenerated
other products are released to the rest of the plant
Calvin cycle
light rxns
initial phase of photosynthesis; light energy is converted to chemical energy
Calvin cycle
