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Which process is most directly driven by light energy?


A) creation of a pH gradient by pumping protons across the thylakoid membrane
B) reduction of NADP+ molecules
C) removal of electrons from chlorophyll molecules
D) ATP synthesis

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Which of the following statements correctly describes a reaction associated with photosystem II?


A) Light energy excites electrons in the thylakoid membrane electron transport chain.
B) Electrons released from the P680 chlorophyll are replaced by electrons derived from water.
C) The P680 chlorophyll donates a pair of electrons directly to NADP+,producing NADPH.
D) Electrons are passed from the P680 chlorophyll to oxygen (O2) .

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The enzyme rubisco plays a critical role in carbon fixation in which of the following types of plants?


A) C3 plants only
B) C4 plants only
C) C3 and C4 plants only
D) C4 and CAM plants only
E) C3,C4,and CAM plants

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Where is the electron transport chain associated with photophosphorylation located in plant cells?


A) thylakoid membranes of chloroplasts
B) stroma of chloroplasts
C) outer membrane of chloroplasts
D) inner membrane of mitochondria

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Photophosphorylation in photosynthesis is most similar to which of the following processes associated with cellular respiration?


A) substrate-level phosphorylation in glycolysis
B) pyruvate oxidation in the production of acetyl-CoA
C) oxidation of NADH in anerobic fermentation
D) oxidative phosphorylation in mitochondria

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Which of the following statements is a correct distinction between autotrophs and heterotrophs?


A) Autotrophs,but not heterotrophs,can nourish themselves beginning with CO2 and other nutrients that are inorganic.
B) Only heterotrophs require chemical compounds from the environment.
C) Cellular respiration is unique to heterotrophs.
D) Only heterotrophs have mitochondria.

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Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?


A) CO2 and glucose
B) H2O and O2
C) ADP,℗i,and NADP+
D) electrons and H+
E) ATP and NADPH

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Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?


A) The light reactions provide ATP and NADPH to the Calvin cycle,and the Calvin cycle returns ADP,℗i,and NADP+ to the light reactions.
B) The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle,and the Calvin cycle provides water and electrons to the light reactions.
C) The light reactions supply the Calvin cycle with CO2 to produce sugars,and the Calvin cycle supplies the light reactions with sugars to produce ATP.
D) The light reactions provide the Calvin cycle with oxygen for carbon fixation,and the Calvin cycle provides the light reactions with sugars to produce ATP.

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CAM plants keep stomata closed in daytime,thus reducing loss of water.They can do this because they


A) fix CO2 into organic acids during the night when temperatures are cooler.
B) fix CO2 into organic acids in the bundle-sheath cells,which do not rely on stomata.
C) fix CO2 into organic acids in the mesophyll cells,which do not rely on stomata.
D) fix CO2 into by combining it with RuBP in the Calvin cycle.
E) obtain CO2 through their roots during the day.

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In photosynthetic cells,which reactions is (are) responsible for the synthesis of ATP by chemiosmosis?


A) photosynthesis only
B) cellular respiration only
C) both photosynthesis and cellular respiration
D) cyclic photophosphorylation only

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P680+ is often considered the strongest biological oxidizing agent.Given its function,why is this necessary?


A) It is the receptor for the most excited electrons in either photosystem.
B) It is the molecule that transfers electrons to the photosynthetic electron transport chain.
C) It transfers its electrons directly to NADP+ to produce NADPH.
D) It obtains electrons from the oxygen atom in a water molecule,so it must have a greater affinity for electrons than oxygen has.
E) It has a positive charge.

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Chemiosmosis in chloroplasts involves which of the following processes?


A) establishment of a proton gradient across the thylakoid membrane
B) diffusion of electrons through the thylakoid membrane
C) reduction of water to produce oxygen
D) formation of glucose from carbon dioxide

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What is the primary function of cyclic electron flow?


A) to produce additional NADPH
B) to produce additional ATP
C) to produce additional oxygen
D) to produce additional carbon dioxide

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How is photosynthesis similar in C4 plants and CAM plants?


A) In both cases,electron transport is not used.
B) Both types of plants make sugar without the Calvin cycle.
C) In both cases,rubisco is not used to fix carbon initially.
D) Both types of plants make most of their sugar in the dark.

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What is the primary function of the pigment molecules in a light-harvesting complex?


A) to split water and release oxygen to the reaction-center chlorophyll
B) to transfer light energy to the reaction-center chlorophyll
C) to synthesize ATP from ADP and ℗i
D) to transfer electrons to the primary electron acceptor

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If plants are grown in the light with CO2 containing a radioactive isotope of oxygen (18O) ,subsequent analysis will show that 18O incorporated in organic molecules first appears in


A) the thylakoid space.
B) the thylakoid membranes.
C) the stroma.
D) mitochondria.

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A reduction in the amount of NADP+ available in plant cells in the light will ultimately result in which of the following effects?


A) an increase in the rate of the Calvin cycle
B) a decrease in the rate of linear electron flow
C) a decrease in the rate of cyclic electron flow
D) an increase in the rate of oxygen production

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Why are C4 plants able to photosynthesize with no apparent photorespiration?


A) They do not participate in the Calvin cycle.
B) They keep their stomata open most of the time in hot,dry climates,which allows for water loss to prevent photorespiration.
C) They keep their stomata closed most of the time in hot,dry climates,which conserves water and oxygen to inhibit photorespiration.
D) They do not use rubisco to fix CO2.
E) They exclude oxygen from their tissues.

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Theodor W.Engelmann illuminated a filament of algae with light that passed through a prism,thus exposing different segments of algae to different wavelengths of light.He added aerobic bacteria and then noted in which areas the bacteria congregated.He found that the largest groups were found in the areas illuminated by the red and blue light.What did Engelmann conclude about the congregation of bacteria in the red and blue areas?


A) Bacteria congregated in these areas due to a local increase in temperature generated by illumination by red and blue light.
B) Bacteria released excess carbon dioxide in these areas.
C) Bacteria congregated in these areas because they are attracted to red and blue light.
D) Bacteria congregated in these areas because they were the areas where the most oxygen was released by the algae.

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Where do the enzymatic reactions of the Calvin cycle take place?


A) stroma of the chloroplast
B) thylakoid membranes
C) matrix of the mitochondria
D) thylakoid space

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