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The light reactions of photosynthesis supply the Calvin cycle with
A. light energy.
B. CO2 and ATP.
C. H2O and NADPH.
D. ATP and NADPH.
E. sugar and O2 .

D

Which of the following sequences correctly represents the flow of electrons during photosynthesis?
A. H20- NADPH - Calvin cycle
B. NADPH - electron transport chain-O2
C.NADPH -O2-CO2
D. NADPH - chlorophyll - Calvin cycle
E. H20- photosystem I - photosystem II

A

How is photosynthesis similar in C4 plants and CAM plants?
A. In both cases, thylakoids are not involved in photosynthesis.
B. In both cases, rubisco is not used to fix carbon initially.
C. In both cases, only photosystem I is used.
D. Both types of plants make most of their sugar in the dark.
E. Both types of plants make sugar without the Calvin cycle.

B

Which of the following statements is a correct distinction between autotrophs and heterotrophs?
A. Only heterotrophs require chemical compounds from the environment.
B. Only heterotrophs have mitochondria.
C. Only heterotrophs require oxygen.
D. Autotrophs, but not heterotrophs, can nourish themselves beginning CO2 with and other nutrients that are inorganic.
E. Cellular respiration is unique to heterotrophs.

D

Which of the following does not occur during the Calvin cycle?
A.consumption of ATP
B. carbon fixation
C. oxidation of NADPH
D. regeneration of the CO2 acceptor
E. release of oxygen

E

In mechanism, photophosphorylation is most similar to
A. the Calvin cycle.
B. reduction of NADP+.
C. carbon fixation.
D. oxidative phosphorylation in cellular respiration.
E. substrate-level phosphorylation in glycolysis.

D

Which process is most directly driven by light energy?
A. removal of electrons from chlorophyll molecules
B. ATP synthesis
C. reduction of NADP+ molecules
D. carbon fixation in the stroma
E. creation of a pH gradient by pumping protons across the thylakoid membrane

A

Plants are photoautotrophs. What does this mean?
A.They synthesize their own food from inorganic materials.
B. They use light energy to drive the synthesis of organic molecules from inorganic materials.
C. They generate oxygen.
D. They are attracted to light.
E. They are the primary consumers of the biosphere.

B

The ultimate source of energy to support most life on Earth is _____.
A. sunlight
B. the carbon cycle
C. chemosynthetic microbes
D. geothermal heat
E. photosynthetic plants

A

Select the most accurate statement describing the basic function of the light reactions of photosynthesis.
A. The basic function of the light reactions of photosynthesis is the conversion of solar energy to chemical energy.
B. The basic function of the light reactions of photosynthesis is the trapping of light energy.
C. The basic function of the light reactions of photosynthesis is the production of glucose.

A

Select the correct molecule that is the main product of the Calvin cycle.
A. Glucose
B. NADPH
C. G3P

C

What is the basic role of CO2 in photosynthesis?
A. CO2 is fixed or incorporated into organic molecules.
B. CO2 is a source of electrons in the formation of organic molecules.
C. CO2 is taken in by plants as a form of inverse respiration, in which carbon dioxide is "breathed in" and oxygen is "breathed out."

A

Select the correct statement about the Calvin cycle.
A. The Calvin cycle has three phases: carbon fixation, reduction, and regeneration of RuBP.
B. The Calvin cycle takes place primarily in the dark.
C. The basic function of the Calvin cycle is the conversion of solar energy to chemical energy.

A

Why are plants classified as producers?
A. Plants are classified as producers because they fix inorganic carbon into organic molecules.
B. Plants are classified as producers because they produce oxygen.
C. Plants are classified as producers because they are at the bottom of the food chain.

A

The photosynthetic membranes are found in the _____ in plant cells.
A. mitochondria
B. nucleus
C. endoplasmic reticulum
D. chloroplasts
E. Golgi apparatus

D

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
A. H2O and O2
B. ADP, i, and NADP+
C. electrons and H+
D. CO2 and glucose
E. ATP and NADPH

E

Where does the Calvin cycle take place?
A. cytoplasm surrounding the chloroplast
B. outer membrane of the chloroplast
C. stroma of the chloroplast
D. interior of the thylakoid (thylakoid space)
E. thylakoid membrane

C

In any ecosystem, terrestrial or aquatic, what group(s) is (are) always necessary?
A. autotrophs and heterotrophs
B. autotrophs
C. producers and primary consumers
D. green plants
E. photosynthesizers

B

When oxygen is released as a result of photosynthesis, it is a direct by-product of
A. the electron transfer system of photosystem I.
B. chemiosmosis.
C. the electron transfer system of photosystem II.
D. reducing NADP+.
E. splitting water molecules.

E

If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), later analysis will show that all of the following molecules produced by the algae contain 18O except
A. ribulose bisphosphate (RuBP).
B. O2.
C. 3-phosphoglycerate.
D. glyceraldehyde 3-phosphate (G3P).
E. glucose.

B

In autotrophic bacteria, where is chlorophyll located?
A. in chloroplast stroma
B. in the nucleoid
C. in chloroplast membranes
D. in the infolded plasma membrane
E. in the ribosomes

D

In the electromagnetic spectrum, the type of radiation that we call visible light occurs between _____.
A. infrared radiation and radio waves
B. X-rays and ultraviolet radiation
C. ultraviolet radiation and infrared radiation
D. radio waves and microwaves
E. infrared radiation and microwaves

C

Which of the following is a product of the light reactions of photosynthesis?
A. NADP+ and RuBP
B. water and CO2
C. oxygen, ATP, and NADPH
D. high-energy photons
E. glyceraldehyde-3-phosphate

C

When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by _____.
A. breaking down ATP
B. removing them from NADPH
C. oxidizing glucose
D. splitting water
E. fixing carbon

D

Photosynthesis is a redox reaction. This means that H2O is _____ during the light reactions and CO2 is _____ during the Calvin cycle.
A. Consumed...reduced
B. oxidized...reduced
C. reduced...reduced
D. consumed...consumed
E. reduced...oxidized

B

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?
A. blue, green, and red
B. green and yellow
C. green, blue, and yellow
D. red and yellow
E. blue and violet

E

Which of the events listed below occurs in the light reactions of photosynthesis?
A. Light is absorbed and funneled to reaction-center chlorophyll a.
B. ATP is phosphorylated to yield ADP.
C. NADP is produced.
D. Carbon dioxide is incorporated into PGA.
E. NADPH is reduced to NADP+.

A

Which statement describes the functioning of photosystem II?
A. The splitting of water yields molecular carbon dioxide as a by-product.
B. The P680 chlorophyll donates a pair of protons to NADP+, which is thus converted to NADPH.
C. The electron vacancies in P680+ are filled by electrons derived from water.
D. Light energy excites electrons in the thylakoid membrane electron transport chain.
E. Photons are passed along to a reaction-center chlorophyll.

C

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be
A. to test for liberation of O2 in the light.
B. to determine if they have thylakoids in the chloroplasts.
C. to test for CO2 fixation in the dark.
D. to do experiments to generate an action spectrum.
E. to test for production of either sucrose or starch.

A

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30,000 molecules of ATP consumed, but only 20,000 molecules of NADPH. Where did the extra ATP molecules come from?
A. chlorophyll
B. linear electron flow
C. photosystem II
D. cyclic electron flow
E. photosystem I

D

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
A. the reduction of NADP+
B. the absorption of light energy by chlorophyll
C. the synthesis of ATP
D. the splitting of water
E. the flow of electrons from photosystem II to photosystem I

C

What does the chemiosmotic process in chloroplasts involve?
A. reduction of water to produce ATP energy
B. diffusion of electrons through the thylakoid membrane
C. movement of water by osmosis into the thylakoid space from the stroma
D. establishment of a proton gradient across the thylakoid membrane
E. formation of glucose, using carbon dioxide, NADPH, and ATP

D

In a plant cell, where are the ATP synthase complexes located?
A. plasma membrane only
B. thylakoid membrane only
C. inner mitochondrial membrane only
D. thylakoid membrane and plasma membrane
E. thylakoid membrane and inner mitochondrial membrane

E

In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from
A. the matrix to the stroma.
B. the thylakoid space to the stroma.
C. the intermembrane space to the matrix.
D. the stroma to the photosystem II.
E. the stroma to the thylakoid space.

E

Which of the following statements best describes the relationship between photosynthesis and respiration?
A. Respiration is anabolic and photosynthesis is catabolic.
B. Photosynthesis occurs only in plants and respiration occurs only in animals.
C. Photosynthesis stores energy in complex organic molecules, whereas respiration releases it.
D. ATP molecules are produced in photosynthesis and used up in respiration.
E. Respiration runs the biochemical pathways of photosynthesis in reverse.

C

Where are the molecules of the electron transport chain found in plant cells?
A. outer membrane of mitochondria
B. cytoplasm
C. matrix of mitochondria
D. thylakoid membranes of chloroplasts
E. stroma of chloroplasts

D

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during
A. neither photosynthesis nor respiration.
B. photosynthesis only.
C. photorespiration only.
D. respiration only.
E. both photosynthesis and respiration.

E

The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during
A. both photosynthesis and respiration.
B. photosynthesis.
C. respiration.
D. neither photosynthesis nor respiration.
E. photorespiration.

D

Generation of proton gradients across membranes occurs during
A. photorespiration.
B. both photosynthesis and respiration.
C. respiration.
D. photosynthesis.
E. neither photosynthesis nor respiration.

B

What is the relationship between wavelength of light and the quantity of energy per photon?
A. They have a direct, linear relationship.
B. They are only related in certain parts of the spectrum.
C. They are logarithmically related.
D. They are separate phenomena.
E. They are inversely related.

E

Some photosynthetic bacteria (e.g., purple sulfur bacteria) have only photosystem I, whereas others (e.g., cyanobacteria) have both photosystem I and photosystem II. Which of the following might this observation imply?
A. Photosystem II may have evolved to be more photoprotective.
B. Cyclic flow is more necessary than linear electron flow.
C. Photosynthesis with only photosystem I is more ancestral.
D. Linear electron flow is more primitive than cyclic flow of electrons.
E. Photosystem II was selected against in some species.

C

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?
A. They protect against oxidative damage from excessive light energy.
B. They reflect orange light and enhance red light absorption by chlorophyll.
C. They serve as accessory pigments to increase light absorption.
D. They take up and remove toxins from the groundwater.
E. They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation.

A

In thylakoids, protons travel through ATP synthase from the thylakoid space to the stroma. Therefore, the catalytic "knobs" of ATP synthase would be located
A. on the stromal side of the membrane.
B. on the pigment molecules of photosystem I and photosystem II.
C. on the ATP molecules themselves.
D. built into the center of the thylakoid stack (granum).
E. on the side facing the thylakoid space.

A

In metabolic processes of cell respiration and photosynthesis, prosthetic groups such as heme and iron-sulfur complexes are encountered in components of the electron transport chain. What do they do?
A. transport protons within the mitochondria and chloroplasts
B. both oxidize and reduce during electron transport
C. act as reducing agents
D. act as oxidizing agents
E. donate electrons

B

In a cyanobacterium, the reactions that produce NADPH occur in
A. the chloroplast, but is not part of photosynthesis.
B. both the light reactions and the Calvin cycle.
C. neither the light reactions nor the Calvin cycle.
D. the light reactions alone.
E. the Calvin cycle alone.

D

The reactions that produce molecular oxygen (O2) take place in
A. the Calvin cycle alone.
B. both the light reactions and the Calvin cycle.
C. the chloroplast, but are not part of photosynthesis.
D. the light reactions alone.
E. neither the light reactions nor the Calvin cycle.

D

The accumulation of free oxygen in Earth's atmosphere began
A. with the origin of chloroplasts in photosynthetic eukaryotic algae.
B. with the origin of land plants.
C. with the origin of photosynthetic bacteria that had photosystem I.
D. with the origin of cyanobacteria that had both photosystem I and photosystem II.
E. with the origin of life and respiratory metabolism.

D

A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask.
A. The dissolved oxygen in the flask with algae will not be different from the control flask at any time.
B. The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark.
C. The dissolved oxygen in the flask with algae will always be higher.
D. The dissolved oxygen in the flask with algae will always be lower.
E. The dissolved oxygen in the flask with algae will be higher in the light, but the same in the dark.

B

The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
A. Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.
B. Other pigments absorb light in addition to chlorophyll a.
C. Oxygen given off during photosynthesis interferes with the absorption of light.
D. Bright sunlight destroys photosynthetic pigments.
E. Green and yellow wavelengths inhibit the absorption of red and blue wavelengths.

B

What wavelength of light in the figure is most effective in driving photosynthesis?
A. 730 mm
B. 420 mm
C. 625 mm
D. 575 mm
E. 475 mm

B

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 noted 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 released excess carbon dioxide in these areas.
B. Bacteria congregated in these areas due to an increase in the temperature of the red and blue light.
C. Bacteria are attracted to red and blue light and thus these wavelengths are more reactive than other wavelengths.
D. Bacteria congregated in these areas because these areas had the most oxygen being released.
E. Bacteria congregated in these areas due to an increase in the temperature caused by an increase in photosynthesis.

D

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 noted that the largest groups were found in the areas illuminated by the red and blue light.
An outcome of this experiment was to help determine
A. the relationship between wavelengths of light and the rate of photosynthesis.
B. the relationship between wavelengths of light and the amount of heat released.
C. the relationship between the concentration of carbon dioxide and the rate of photosynthesis.
D. the relationship between heterotrophic and autotrophic organisms.
E. the relationship between wavelengths of light and the rate of aerobic respiration.

A

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 noted that the largest groups were found in the areas illuminated by the red and blue light.
If you ran the same experiment without passing light through a prism, what would you predict?
A. The number of bacteria present would decrease due to an increase in the carbon dioxide concentration.
B. There would be no difference in results.
C. The number of bacteria would decrease due to a decrease in the temperature of the water.
D. The bacteria would be relatively evenly distributed along the algal filaments.
E. The number of bacteria present would increase due to an increase in the carbon dioxide concentration.

D

In the thylakoid membranes, what is the main role of the pigment molecules in a light-harvesting complex?
A. transfer electrons to ferredoxin and then NADPH
B. synthesize ATP from ADP and i
C. transfer light energy to the reaction-center chlorophyll
D. split water and release oxygen to the reaction-center chlorophyll
E. concentrate photons within the stroma

C

What are the products of linear electron flow?
A. heat and fluorescence
B. ADP and NADP+
C. P700 and P680
D. ATP and NADPH
E. ATP and P700

D

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen?
A. Cyclic photophosphorylation will occur.
B. The isolated chloroplasts will generate oxygen gas.
C. The Calvin cycle will be activated.
D. The isolated chloroplasts will reduce NADP+ to NADPH.
E. The isolated chloroplasts will make ATP.

E

Reduction of oxygen to form water occurs during
A. respiration only.
B. neither photosynthesis nor respiration.
C. the dark reactions only.
D. both photosynthesis and respiration.
E. photosynthesis only.

A

P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?
A. It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.
B. It transfers its electrons to reduce NADP+ to NADPH.
C. It has a positive charge.
D. It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system.
E. It is the receptor for the most excited electron in either photosystem.

A

A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed.
What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure?
A. UV light
B. green light
C. full-spectrum white light
D. a mixture of blue and red light
E. yellow light

D

Halobacterium has a photosynthetic membrane that appears purple. Its photosynthetic action spectrum is the inverse of the action spectrum for green plants. (That is, the Halobacterium action spectrum has a peak where the green plant action spectrum has a trough.) What wavelengths of light do the Halobacterium photosynthetic pigments absorb?
A. blue, green, and red
B. green and yellow
C. red and yellow
D. blue and red
E. red and green

B

Reduction of NADP+ occurs during
A. neither photosynthesis nor respiration.
B. photosynthesis.
C. respiration.
D. both photosynthesis and respiration.

B

A gardener is concerned that her greenhouse is getting too hot from too much light, and seeks to shade her plants with colored translucent plastic sheets, the color of which allows passage of only that wavelength. What color should she use to reduce overall light energy, but still maximize plant growth?
A. blue
B. any color will work equally well
C. green
D. yellow
E. orange

A

Which of the following are directly associated with photosystem I?
A. generation of molecular oxygen
B. extraction of hydrogen electrons from the splitting of water
C. harvesting of light energy by ATP
D. passing electrons to the thylakoid membrane electron transport chain
E. receiving electrons from the thylakoid membrane electron transport chain

E

Cyclic electron flow may be photoprotective (protective to light-induced damage). Which of the following experiments could provide information on this phenomenon?
A. use plants that can carry out both linear and cyclic electron flow, or only one or another of these processes, and compare their light absorbance at different wavelengths and different light intensities
B. use mutated organisms that can grow but that cannot carry out cyclic flow of electrons and compare their abilities to photosynthesize in different light intensities against those of wild-type organisms
C. use bacteria with only cyclic flow and measure the number and types of photosynthetic pigments they have in their membranes
D. use plants with only photosystem I operative and measure how much damage occurs at different wavelengths
E. use bacteria that have only cyclic flow and look for their frequency of mutation damage at different light intensities

B

Which of the following products of the light reactions of photosynthesis is consumed during the Calvin cycle?
A. oxygen
B. water
C. ADP + Pi
D. sugar
E. NADPH

E

The overall function of the Calvin cycle is _____.
A. oxidizing glucose
B. capturing sunlight
C. splitting water
D. producing carbon dioxide
E. making sugar

E

Where do the enzymatic reactions of the Calvin cycle take place?
A. thylakoid membranes
B. cytosol around the chloroplast
C. matrix of the mitochondria
D. stroma of the chloroplast
E. thylakoid space

D

What is the primary function of the Calvin cycle?
A. transport RuBP out of the chloroplast
B. synthesize simple sugars from carbon dioxide
C. split water and release oxygen
D. use NADPH to release carbon dioxide
E. use ATP to release carbon dioxide

B

In C3 photosynthesis, the reactions that require ATP take place in
A. both the light reactions and the Calvin cycle.
B. the chloroplast, but is not part of photosynthesis.
C. the light reactions alone.
D. neither the light reactions nor the Calvin cycle.
E. the Calvin cycle alone.

E

The NADPH required for the Calvin cycle comes from
A. the citric acid cycle.
B. oxidative phosphorylation.
C. reactions initiated in photosystem II.
D. glycolysis.
E. reactions initiated in photosystem I.

E

Reactions that require CO2 take place in
A. both the light reactions and the Calvin cycle.
B. the light reactions alone.
C. the Calvin cycle alone.
D. the chloroplast, but is not part of photosynthesis.
E. neither the light reactions nor the Calvin cycle.

C

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 carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions.
B. There is no relationship between the light reactions and the Calvin cycle.
C. The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split.
D. 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.
E. The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, i, and NADP+ to the light reactions.

E

In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle?
A. regeneration of ATP from ADP
B. addition of a pair of electrons from NADPH
C. regeneration of NADP+
D. inactivation of RuBP carboxylase enzyme
E. regeneration of RuBP

E

The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find?
A. The pH of the thylakoid space is higher than that anywhere else in the cell.
B. The pH of the stroma is lower than that of the other two measurements.
C. There is no consistent relationship.
D. The pH within the thylakoid is less than that of the stroma.
E. The pH of the stroma is higher than that of the thylakoid space but lower than that of the cytosol.

D

The phylogenetic distribution of the enzyme rubisco is limited to
A. all known photoautotrophs, both bacterial and eukaryotic.
B. all photosynthetic eukaryotes.
C. all living cells.
D. C3 and C4 plants.
E. C3 plants only.

A

Use the following figure and the compounds labeled A, B, C, D, and E to answer the following question.
If ATP used by this plant is labeled with radioactive phosphorus, which molecule or molecules of the Calvin cycle will be radioactively labeled first?
A. B, C, D, and E
B. B and E only
C. B, C, and D only
D. B only
E. B and C only

B

Use the following figure and the compounds labeled A, B, C, D, and E to answer the following question.
Which molecule(s) of the Calvin cycle is (are) also found in glycolysis?
A. B, C, and E only
B. B, C, D, and 3-phosphoglycerate only
C. 3-phosphoglycerate only
D. B, C, E, and 3-phosphoglycerate
E. E only

B

Use the following figure and the compounds labeled A, B, C, D, and E to answer the following question.
To identify the molecule that accepts CO2, Calvin and Benson manipulated the carbon-fixation cycle by either cutting off CO2 or cutting off light from cultures of photosynthetic algae. They then measured the concentrations of various metabolites immediately following the manipulation. How would these experiments help identify the CO2 acceptor? Study the figure to help you in determining the correct answer.
A. The CO2 acceptor concentration would increase when either the CO2 or light are cut off.
B. The CO2 acceptor concentration would increase when the CO2 is cut off, but decrease when the light is cut off.
C. The CO2 acceptor concentration would stay the same regardless of the CO2 or light.
D. The CO2 acceptor concentration would decrease when the CO2 is cut off, but increase when the light is cut off.
E. The CO2 acceptor concentration would decrease when either the CO2 or light are cut off.

B

A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed.
If the power fails and the lights go dark, what will happen to CO2 levels?
A. CO2 will remain balanced because plants will continue to fix CO2 in the dark.
B. CO2 will fall because plants will cease to respire in the dark.
C. CO2 will rise as a result of animal respiration only.
D. CO2 will rise as a result of both animal and plant respiration.
E. CO2 will fall because plants will increase CO2 fixation.

D

What compound provides the reducing power for the Calvin cycle reactions?
A. ATP
B. NADH
C. NADP+
D. NADPH
E. NAD+

D

Use the following figure and the compounds labeled A, B, C, D, and E to answer the following question.
If the carbon atom of each of the incoming molecules is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?
A. B and D only
B. C only
C. B and C only
D. C, D, and E only
E. B, C, D, and E

E

C4 plants occur more commonly in desert conditions because _____.
A. the stomata open at night and close in the day
B. they store carbon by incorporating CO2 into organic acids that are later catabolized
C. they produce carbon dioxide internally via photorespiration
D. they produce water as a product of their photosynthetic pathways
E. they can fix carbon at the lower CO2 concentrations that develop when the stomata are closed

E

Photorespiration occurs when rubisco reacts RuBP with
A. NADPH.
B. glyceraldehyde 3-phosphate.
C. O2.
D. 3-phosphoglycerate.
E. CO2.

C

In an experiment studying photosynthesis performed during the day, you provide a plant with radioactive carbon (14C) dioxide as a metabolic tracer. The 14C is incorporated first into oxaloacetate. The plant is best characterized as a
A. C3 plant.
B. heterotroph.
C. chemoautotroph.
D. CAM plant.
E. C4 plant.

E

Why are C4 plants able to photosynthesize with no apparent photorespiration?
A. They use PEP carboxylase to initially fix CO2.
B. They are adapted to cold, wet climates.
C. They conserve water more efficiently.
D. They do not participate in the Calvin cycle.
E. They exclude oxygen from their tissues.

A

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.
B. use the enzyme phosphofructokinase, which outcompetes rubisco for CO2.
C. fix CO2 into sugars in the bundle-sheath cells.
D. fix CO2 into pyruvate in the mesophyll cells.
E. use photosystem I and photosystem II at night.

A

The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why?
A. C4 plants allow less water loss but CAM plants allow more water loss.
B. C4 compromises on water loss and CAM compromises on photorespiration.
C. Each one minimizes both water loss and rate of photosynthesis.
D. CAM plants allow more water loss, while C4 plants allow less CO2 into the plant.
E. Both minimize photorespiration but expend more ATP during carbon fixation.

E

If plant gene alterations cause the plants to be deficient in photorespiration, what would most probably occur?
A. Less ATP would be generated.
B. Photosynthetic efficiency would be reduced at low light intensities.
C. There would be more light-induced damage to the cells.
D. Less oxygen would be produced.
E. Cells would carry on the Calvin cycle at a much slower rate.

C

Compared to C3 plants, C4 plants
A. have higher rates of photorespiration.
B. make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria.
C. do not use rubisco for carbon fixation.
D. grow better under cool, moist conditions.
E. can continue to fix CO2 even at relatively low CO2 concentrations and high oxygen concentrations.

E

Plants photosynthesize only in the light. Plants respire
A. in the light only.
B. never-they get their ATP from photophosphorylation.
C. in the dark only.
D. only when excessive light energy induces photorespiration.
E. both in light and dark.

E

Referring to the figure, oxygen would inhibit the CO2 fixation reactions in
A. both cell I and cell II.
B. cell I only.
C. cell I during the night and cell II during the day.
D. neither cell I nor cell II.
E. cell II only.

E

Photorespiration lowers the efficiency of photosynthesis by
A. consuming carbon dioxide.
B. denaturing rubisco.
C. producing ribulose bisphosphate.
D. reducing the amount of 3-phosphoglycerate forme.
E. generating excess ATP.

D

What would be the expected effect on plants if the atmospheric CO2 concentration was doubled?
A. Plant growth will not be affected because atmospheric CO2 concentrations are never limiting for plant growth.
B. C4 plants will have faster growth; C3 plants will be minimally affected.
C. C3 plants will have faster growth; C4 plants will be minimally affected.
D. C3 plants will have faster growth; C4 plants will have slower growth.
E. All plants will experience increased rates of photosynthesis.

C

Which of the following statements is true concerning the figure?
A. It represents the type of cell structures found in CAM plants.
B. It represents a C3 photosynthetic system.
C. It represents a relationship between plant cells that photosynthesize and those that cannot.
D. It represents an adaptation that maximizes photorespiration.
E. It represents cell processes involved in C4 photosynthesis.

E

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