Campbell Biology 10th Edition: ch9-10 Flashcards

1) Substrate-level phosphorylation occurs _____.

A) in glycolysis
B) in the citric acid cycle
C) in both glycolysis and the citric acid cycle

D) during oxidative phosphorylation

2) The molecule that functions as the reducing agent (electron donor) in a redox or oxidation- reduction reaction _____.
A) gains electrons and gains potential energy
B) loses electrons and loses potential energy

C) gains electrons and loses potential energy
D) loses electrons and gains potential energy

3) When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is _____.
A) reduced, and energy is released
B) reduced, and energy is consumed

C) oxidized, and energy is consumed
D) oxidized, and energy is released

4) Which of the listed statements describes the results of the following reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

A) C6H12O6 is oxidized and O2 is reduced.

B) O2 is oxidized and H2O is reduced.
C) CO2 is reduced and O2 is oxidized.
D) O2 is reduced and CO2 is oxidized.

5) When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes _____.
A) hydrolyzed
B) oxidized

C) reduced
D) an oxidizing agent

7) Which of the following statements about NAD+ is true?
A) NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. B) NAD+ has more chemical energy than NADH.
C) NAD+ can donate electrons for use in oxidative phosphorylation.

D) In the absence of NAD+, glycolysis can still function.

8) The oxygen consumed during cellular respiration is involved directly in which process or event?
A) glycolysis
B) accepting electrons at the end of the electron transport chain

C) the citric acid cycle
D) the oxidation of pyruvate to acetyl CoA

10) A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply?
A) He or she has to sit down and rest.
B) Catabolic processes are activated that generate more ATP.

C) ATP is transported into the cell from the circulatory system.
D) Other cells take over, and the muscle cells that have used up their ATP cease to function.

11) Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?
A) 0%
B) 2%

C) 38%
D) 100%

13) Starting with one molecule of glucose, the energy-containing products of glycolysis are _____.

A) 2 NAD+, 2 pyruvate, and 2 ATP

B) 2 NADH, 2 pyruvate, and 2 ATP

C) 2 FADH2, 2 pyruvate, and 4 ATP

D) 6 CO2, 2 pyruvate, and 2 ATP

14) In glycolysis, for each molecule of glucose oxidized to pyruvate _____.

A) two molecules of ATP are used and two molecules of ATP are produced.

B) two molecules of ATP are used and four molecules of ATP are produced.

C) four molecules of ATP are used and two molecules of ATP are produced.

D) two molecules of ATP are used and six molecules of ATP are produced.

15) Which kind of metabolic poison would most directly interfere with glycolysis?

A) an agent that reacts with oxygen and depletes its concentration in the cell
B) an agent that binds to pyruvate and inactivates it
C) an agent that closely mimics the structure of glucose but is not metabolized

D) an agent that reacts with NADH and oxidizes it to NAD+

16) Most of the CO2 from the catabolism of glucose is released during _____.

A) glycolysis
B) electron transport
C) chemiosmosis
D) the citric acid cycle

17) Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _____.

A) acetyl-CoA
B) glucose

C) pyruvate
D) NADH

18) Which electron carrier(s) function in the citric acid cycle?

A) NAD+ only
B) NADH and FADH2

C) the electron transport chain
D) ADP and ATP

19) If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production?
A) There would be no change in ATP production, but we would observe an increased rate of carbon dioxide production.

B) The rates of ATP production and carbon dioxide production would both increase.
C) The rate of ATP production would decrease, but the rate of carbon dioxide production would increase.
D) Rates of ATP and carbon dioxide production would probably both decrease.

20) Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

A) glycolysis and the oxidation of pyruvate to acetyl CoA
B) oxidation of pyruvate to acetyl CoA and the citric acid cycle

C) oxidative phosphorylation and fermentation
D) fermentation and glycolysis

21) If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle?
A) 1/6
B) 1/3

C) 2/3
D) all of it

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A.

25) The three listed steps result in the formation of _____.

A) acetyl CoA, O2, and ATP

B) acetyl CoA, FADH2, and CO2

C) acetyl CoA, NADH, and CO2

D) acetyl CoA, NAD+, ATP, and CO2

26) Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?

A) glyceraldehyde 3-phosphate
B) oxaloacetate
C) acetyl CoA
D) citrate

27) Which of the following events takes place in the electron transport chain?
A) the breakdown of glucose into two pyruvate molecules
B) the breakdown of an acetyl group to carbon dioxide
C) the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle

D) substrate-level phosphorylation

28) The electron transport chain _____.

A) is a series of redox reactions
B) is a series of substitution reactions

C) is driven by ATP consumption

D) takes place in the cytoplasm of prokaryotic cells

29) The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains _____.
A) how ATP is synthesized by a proton motive force
B) how electron transport can fuel substrate-level phosphorylation

C) the sequence of the electron transport chain molecules
D) the reduction of oxygen to water in the final steps of oxidative metabolism

30) During aerobic respiration, electrons travel downhill in which sequence?

A) glucose → NADH → electron transport chain → oxygen
B) glucose → pyruvate → ATP → oxygen
C) glucose → ATP → electron transport chain → NADH

D) food → glycolysis → citric acid cycle → NADH → ATP

31) Where are the proteins of the electron transport chain located?

A) mitochondrial outer membrane
B) mitochondrial inner membrane
C) mitochondrial intermembrane space

D) mitochondrial matrix

32) During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
A) NADH
B) ATP

C) ADP + Pi
D) FADH2

33) The primary role of oxygen in cellular respiration is to _____.
A) yield energy in the form of ATP as it is passed down the respiratory chain

B) act as an acceptor for electrons and hydrogen, forming water
C) combine with carbon, forming CO2

D) combine with lactate, forming pyruvate

34) During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?
A) carbon dioxide (CO2)

B) glucose (C6H12O6)
C) molecular oxygen (O2)

D) pyruvate (C3H3O3-)

35) In chemiosmosis, what is the most direct source of energy that is used to convert ADP + Pi to ATP?

A) energy released as electrons flow through the electron transport system
B) energy released from substrate-level phosphorylation
C) energy released from movement of protons through ATP synthase, down their electrochemical gradient
D) No external source of energy is required because the reaction is exergonic.

36) Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?
A) mitochondrial outer membrane
B) mitochondrial inner membrane

C) mitochondrial intermembrane space
D) mitochondrial matrix

37) When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the _____.
A) formation of ATP

B) reduction of NAD+
C) creation of a proton-motive force
D) lowering of pH in the mitochondrial matrix

38) Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?

A) 2
B) 4
C) 18-24
D) 30-32

39) The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of _____.

A) active transport
B) an endergonic reaction coupled to an exergonic reaction

C) a reaction with a positive ΔG
D) allosteric regulation

40) If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
A) 0

B) 12
C) 14
D) 26

42) You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave his body?
A) It was released as CO2 and H2O.
B) It was converted to heat and then released.

C) It was converted to ATP, which weighs much less than fat. D) It was converted to urine and eliminated from the body.

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP.

43) After the disruption, when electron transfer and ATP synthesis still occur, what must be present?
A) all of the electron transport proteins and ATP synthase
B) all of the electron transport system and the ability to add CoA to acetyl groups

C) the ATP synthase system
D) the electron transport system

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP.

44) These inside-out membrane vesicles will _____.
A) become acidic inside the vesicles when NADH is added
B) become alkaline inside the vesicles when NADH is added
C) make ATP from ADP and Pi if transferred to a pH 4 buffered solution after incubation in a

pH 7 buffered solution
D) hydrolyze ATP to pump protons out of the interior of the vesicle to the exterior

45) Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in _____.

A) all cells, but only in the presence of oxygen
B) only eukaryotic cells, in the presence of oxygen
C) only in mitochondria, using either oxygen or other electron acceptors

D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

46) Which of the following normally occurs regardless of whether or not oxygen (O2) is present?

A) glycolysis
B) fermentation
C) citric acid cycle
D) oxidative phosphorylation (chemiosmosis)

47) Which of the following occurs in the cytosol of a eukaryotic cell?

A) glycolysis and fermentation
B) fermentation and chemiosmosis
C) oxidation of pyruvate to acetyl CoA

D) citric acid cycle

48) In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of _____.
A) ATP, CO2, and ethanol (ethyl alcohol)

B) ATP, CO2, and lactate
C) ATP, NADH, and pyruvate

D) ATP, pyruvate, and acetyl CoA

49) One function of both alcohol fermentation and lactic acid fermentation is to _____.

A) reduce NAD+ to NADH

B) reduce FAD+ to FADH2
C) oxidize NADH to NAD+

D) reduce FADH2 to FAD+

50) An organism is discovered that thrives in both the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism _____.
A) is a normal eukaryotic organism

B) is photosynthetic
C) is an anaerobic organism
D) is a facultative anaerobe

51) Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

A) It produces much less ATP than does oxidative phosphorylation.
B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.

C) It is found in prokaryotic cells but not in eukaryotic cells.
D) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.

52) Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?
A) glucose
B) proteins

C) fatty acids
D) Such yeast cells will not be capable of catabolizing any food molecules, and therefore, will die.

53) What is the oxidizing agent in the following reaction?

Pyruvate + NADH + H+ → Lactate + NAD+

A) NADH

B) NAD+
C) lactate
D) pyruvate

55) Glycolysis is active when cellular energy levels are _____; the regulatory enzyme, phosphofructokinase, is _____ by ATP.
A) low; activated
B) low; inhibited

C) high; activated
D) high; inhibited

57) A young dog has never had much energy. He is brought to a veterinarian for help and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition?

A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
B) His cells cannot move NADH from glycolysis into the mitochondria.
C) His cells lack the enzyme in glycolysis that forms pyruvate.

D) His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.

58) Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in _____.
A) photosynthetic cells in the light, while photosynthesis occurs concurrently
B) cells that are storing glucose only

C) all cells all the time
D) photosynthesizing cells in the light and in other tissues in the dark

60) Fatty acids usually have an even number of carbons in their structures. They are catabolized by a process called beta-oxidation. The end products of the metabolic pathway are acetyl groups of acetyl CoA molecules. These acetyl groups _____.
A) directly enter the electron transport chain

B) directly enter the energy-yielding stages of glycolysis

C) are directly decarboxylated by pyruvate dehydrogenase

D) directly enter the citric acid cycle

1) The process of photosynthesis probably originated _____.

A) in plants
B) in prokaryotes
C) in fungi

D) three separate times during evolution

3) Plants photosynthesize _____.
A) only in the light but respire only in the dark

B) only in the dark but respire only in the light

C) only in the light but respire in light and dark

D) and respire only in the light

4) Early investigators thought the oxygen produced by photosynthetic plants came from carbon dioxide. In fact, it comes from _____.
A) water
B) glucose

C) air
D) electrons from NADPH

5) 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) glyceraldehyde 3-phosphate (G3P)
B) glucose

C) ribulose bisphosphate (RuBP)

D) O2

6) Every ecosystem must have _____.

A) autotrophs and heterotrophs
B) producers and primary consumers

C) photosynthesizers

D) autotrophs

7) When oxygen is released as a result of photosynthesis, it is a direct by-product of _____.

A) splitting water molecules
B) chemiosmosis
C) the electron transfer system of photosystem I

D) the electron transfer system of photosystem II

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.

11) What did Engelmann conclude about the congregation of bacteria in the red and blue areas?

A) Bacteria congregated in these areas due to an increase in the temperature of the red and blue light.
B) Bacteria congregated in these areas because these areas had the most oxygen being released.

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 due to an increase in the temperature caused by an increase in photosynthesis.

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.

12) An outcome of Engelmann's experiment was to help determine the relationship between _____.
A) wavelengths of light and the rate of aerobic respiration
B) wavelengths of light and the amount of heat released

C) wavelengths of light and the rate of photosynthesis
D) the concentration of carbon dioxide and the rate of photosynthesis

15) 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) red and yellow
B) blue, green, and red
C) green and yellow
D) blue and red

16) Why are there several structurally different pigments in the reaction centers of photosystems?
A) Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain.
B) This arrangement enables the plant to absorb light energy of a variety of wavelengths.
C) They enable the plant to absorb more photons from light energy, all of which are at the same wavelength.
D) They enable the reaction center to excite electrons to a higher energy level.

17) If pigments from a particular species of plant are extracted and subjected to paper chromatography, which of the following is most likely?
A) Paper chromatography for the plant would isolate a single band of pigment that is characteristic of that particular plant.

B) Paper chromatography would separate the pigments from a particular plant into several bands.

C) The isolated pigments would be some shade of green.
D) Paper chromatography would isolate only the pigments that reflect green light.

18) In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and _____.
A) carotenoids and other pigments are still present in the leaves
B) the degraded chlorophyll changes into many other colors

C) water supply to the leaves has been reduced
D) sugars are sent to most of the cells of the leaves

19) What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?
A) ATP is synthesized from the energy absorbed.
B) A carboxylation reaction of the Calvin cycle occurs.

C) Electrons are stripped from NADPH.
D) An electron is excited.

20) As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy?
A) It excites electrons of the reaction center of photosystem I.
B) It is lost as heat.

C) It is used to establish and maintain a proton gradient.

D) It is used to phosphorylate NAD+ to NADPH, the molecule that accepts electrons from photosystem I.

21) The final electron acceptor associated with photosystem I is _____.

A) oxygen
B) water
C) NADP

D) NADPH

22) The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come?
A) the electron carrier, plastocyanin
B) photosystem I

C) water
D) oxygen

23) In the thylakoid membranes, the pigment molecules in a light-harvesting complex _____.

A) split water and release oxygen from the reaction-center chlorophyll
B) absorb and transfer light energy to the reaction-center chlorophyll
C) synthesize ATP from ADP and

Pi
D) transfer electrons to ferredoxin and then NADPH

24) Which of the following are directly associated with photosystem I?
A) receiving electrons from the thylakoid membrane electron transport chain

B) generation of molecular oxygen
C) extraction of hydrogen electrons from the splitting of water
D) passing electrons to the cytochrome complex

25) 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 to _____.

A) determine if they have thylakoids in the chloroplasts
B) test for liberation of O2 in the light

C) test for CO2 fixation in the dark
D) do experiments to generate an action spectrum

26) What are the products of linear electron flow?

A) heat and fluorescence
B) ATP and P700
C) ATP and NADPH

D) ADP and NADP+

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

28) Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will most directly affect the _____.
A) splitting of water
B) flow of electrons from photosystem II to photosystem I

C) synthesis of ATP

D) reduction of NADP+

29) In a plant cell, where are the ATP synthase complexes located? A) thylakoid membrane only
B) inner mitochondrial membrane only
C) thylakoid membrane and inner mitochondrial membrane

D) thylakoid membrane and plasma membrane

30) In mitochondria, chemiosmosis moves protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis moves protons from the _____.
A) matrix to the stroma
B) stroma to the thylakoid space

C) intermembrane space to the matrix
D) thylakoid space to the stroma

31) Which of the following statements best describes the relationship between photosynthesis and respiration?
A) Respiration runs the biochemical pathways of photosynthesis in reverse.
B) Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules

C) Photosynthesis occurs only in plants; respiration occurs only in animals.

D) Photosynthesis is catabolic; respiration is anabolic.

32) In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during _____.
A) photosynthesis only
B) respiration only

C) photosynthesis and respiration
D) neither photosynthesis nor respiration

33) Carbon dioxide is split to form oxygen gas and carbon compounds _____.

A) during photosynthesis
B) during respiration
C) during photosynthesis and respiration

D) in neither photosynthesis nor respiration

34) What is the relationship between the wavelength of light and the quantity of energy per photon?
A) They have a direct, linear relationship.
B) They are inversely related.

C) They are logarithmically related.
D) They are separate phenomena.

35) P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?
A) It is the receptor for the most excited electron in either photosystem of photosynthesis.
B) It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system.

C) It transfers its electrons to reduce NADP+ to NADPH.
D) It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.

36) 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 serve as accessory pigments to increase light absorption.
B) They protect against oxidative damage from excessive light energy.

C) They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation.

D) They reflect orange light and enhance red light absorption by chlorophyll.

37) In a plant, the reactions that produce molecular oxygen (O2) take place in _____.

A) the light reactions alone
B) the Calvin cycle alone
C) the light reactions and the Calvin cycle
D) neither the light reactions nor the Calvin cycle

38) The accumulation of free oxygen in Earth's atmosphere began with the origin of _____.

A) life and respiratory metabolism
B) cyanobacteria using photosystem II
C) chloroplasts in photosynthetic eukaryotic algae

D) land plants

39) In its mechanism, photophosphorylation is most similar to _____.

A) substrate-level phosphorylation in glycolysis
B) oxidative phosphorylation in cellular respiration
C) the Calvin cycle

D) reduction of NADP+

40) Which process is most directly driven by light energy?
A) creation of a pH gradient by pumping protons across the thylakoid membrane

B) carbon fixation in the stroma

C) reduction of NADP+ molecules
D) removal of electrons from chlorophyll molecules

41) 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) green
B) blue
C) orange
D) Any color will work equally well.

42) 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. The dissolved oxygen in the flask with algae will _____.

A) always be higher
B) always be lower
C) be higher in the light, but the same in the dark

D) be higher in the light, but lower in the dark

43) Which of the following 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, Pi, and NADP+

D) ATP and NADPH

44) Where does the Calvin cycle take place?

A) stroma of the chloroplast
B) thylakoid membrane
C) interior of the thylakoid (thylakoid space) D) outer membrane of the chloroplast

45) What is the primary function of the Calvin cycle?

A) use NADPH to release carbon dioxide
B) split water and release oxygen
C) transport RuBP out of the chloroplast

D) synthesize simple sugars from carbon dioxide

46) 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) addition of a pair of electrons from NADPH

B) regeneration of ATP from ADP

C) regeneration of RuBP

D) regeneration of NADP+

49) Which of the following sequences correctly represents the flow of electrons during photosynthesis?
A) NADPH → O2 → C O2
B) H2O → NADPH → Calvin cycle

C) NADPH → chlorophyll → Calvin cycle
D) NADPH → electron transport chain → O2

50) Which of the following does NOT occur during the Calvin cycle?

A) oxidation of NADPH
B) release of oxygen
C) regeneration of the CO2 acceptor

D) consumption of ATP

51) What compound provides the reducing power for Calvin cycle reactions?

A) ATP
B) NADH

C) NADP+
D) NADPH

52) What would be the expected effect on plants if the atmospheric CO2 concentration was doubled?

A) All plants would experience increased rates of photosynthesis.
B) C3 plants would have faster growth; C4 plants would be minimally affected.

C) C4 plants would have faster growth; C3 plants would be minimally affected.

D) C3 plants would have faster growth; C4 plants would have slower growth.

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

A) They do not participate in the Calvin cycle.
B) They use PEP carboxylase to initially fix CO2.

C) They conserve water more efficiently.
D) They exclude oxygen from their tissues.

54) CAM plants keep stomata closed in the daytime, thus reducing loss of water. They can do this because they _____.
A) fix CO2 into organic acids during the night
B) fix CO2 into sugars in the bundle-sheath cells

C) fix CO2 into pyruvate in the mesophyll cells

D) use photosystem I and photosystem II at night

55) The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why?

A) Each one minimizes both water loss and rate of photosynthesis.
B) C4 compromises on water loss and CAM compromises on photorespiration.

C) Both minimize photorespiration but expend more ATP during carbon fixation.
D) CAM plants allow more water loss, while C4 plants allow less CO2 into the plant.

56) If plant gene alterations cause plants to be deficient in photorespiration, what would most probably occur?
A) Photosynthetic efficiency would be reduced at low light intensities.
B) Cells would carry on the Calvin cycle at a much slower rate.

C) There would be more light-induced damage to the cells.

D) Less oxygen would be produced.

57) Compared to C3 plants, C4 plants _____.
A) can continue to fix CO2 even at lower CO2 concentrations and higher oxygen concentrations

B) have higher rates of photorespiration
C) do not use rubisco for carbon fixation
D) make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria

60) Photorespiration _____.
A) generates carbon dioxide and consumes ATP and oxygen
B) generates ATP and sugars and consumes oxygen and carbon dioxide

C) generates oxygen and consumes ATP, carbon dioxide, and sugars

D) consumes carbon dioxide and generates ATP, sugars, and oxygen