Fill in the Blank
1. During the light reactions of photosynthesis, the synthesis of _______ is coupled to the diffusion of protons.
Answer: ATP
2. Atmospheric CO
2
enters plant leaves through openings called _______.
Answer: stomata
3. In the 1800s, the summarized chemical reaction for photosynthesis was incorrect because it left out _______ as a product.
Answer: water
4. In noncyclic photophosphorylation, the electrons for the reduction of chlorophyll in photosystem II come from _______.
Answer: water
5. When _______ are exposed to light and CO
2
, four-carbon compounds are the first carbon-containing products.
Answer: C
4
plants
6. During the process of _______ , rubisco catalyzes the reaction of RuBP with oxygen.
Answer: photorespiration
7. A group of scientists led by _______ conducted experiments demonstrating that RuBP is the CO
2
acceptor in the dark reactions of photosynthesis.
Answer: Calvin
8. When researchers shifted isolated chloroplasts from a low pH solution to a more alkaline solution, ATP synthesis occurred, even in the absence of light. This experiment was used to support the _______ mechanism of ATP formation in chloroplasts.
Answer: chemiosmotic
9. During cyclic photophosphorylation, the energy of photons is converted to the chemical energy of the product, _______.
Answer: ATP
10. In C
3
plants, the Calvin–Benson cycle occurs in the chloroplasts of _______ cells, whereas in C
4
plants the cycle occurs in the _______ cells.

Answer: mesophyll; bundle sheath
11. In both photosynthesis and respiration, _______ synthesis is coupled to the diffusion of protons across a membrane.
Answer: ATP
12. The dark reactions take place in the (dark/light) _______.
Answer: light
13. NADP is the abbreviation for _______.
Answer: nicotinamide adenine dinucleotide phosphate
14. The Calvin–Benson cycle is sometimes called the _______.
Answer: dark reactions
15. The O
2
found in Earth’s atmosphere is generated from the photosystem _______ of noncyclic photophosphorylation.
Answer: II
16. During cyclic photophosphorylation, _______ rather than NADP
+
receives the electron from ferredoxin.
Answer: plastoquinone
17. The most abundant enzyme in the biosphere is _______.
Answer: rubisco (or RuBP carboxylase)
18. The absorption spectrum of chlorophyll a is (different from/similar to) _______ the action spectrum of chlorophyll a .
Answer: similar to
19. The wide range of wavelengths that photons can have is shown by the _______.
Answer: electromagnetic spectrum
Multiple Choice
1. How do red and blue light differ from one another? a. They differ in intensity. b. They have a different number of photons in each quantum. c. Their wavelengths are different. d. They differ in duration. e. Red is radiant, whereas blue is electromagnetic.
Answer: c
2. The wavelength of X rays is shorter than the wavelength of infrared rays. Which of the following is true? a. X rays have more energy per photon than infrared rays have.

b. X rays have a smaller value for Planck’s constant than do infrared waves. c. X rays have a different absorption spectrum than do infrared waves. d. X rays and infrared waves have the same frequency. e. Infrared waves are in the ground state, whereas X rays are in the excited state.
Answer: a
3. A molecule has an absorption spectrum that shows maximum absorption within the wavelengths of visible light. This molecule is a. a reducing agent. b. a quantum. c. a photon. d. electromagnetic radiation. e. a pigment.
Answer: e
4. When white light strikes a blue pigment, blue light is a. reduced. b. absorbed. c. converted to chemical energy. d. scattered or transmitted. e. used to synthesize ATP.
Answer: d
5. A graph that plots the rate at which CO
2
is converted to glucose versus the wavelength of light illuminating a leaf is called a. a Planck equation. b. an absorption spectrum. c. enzyme kinetics. d. an electromagnetic spectrum. e. an action spectrum.
Answer: e
6. The photosynthetic pigment chlorophyll a absorbs a. infrared light. b. orange-red and blue light. c. X rays. d. gamma rays. e. white light.
Answer: b
7. Accessory pigments a. play no role in photosynthesis. b. transfer energy from chlorophyll to the electron transport chain. c. absorb only in the red wavelengths. d. allow plants to absorb visible light of intermediate wavelengths. e. transfer electrons to NADP.

Answer: d
8. Why is the absorption spectrum of chlorophyll a not identical to the action spectrum of photosynthesis? a. Accessory pigments contribute energy to drive photosynthesis. b. Chlorophyll a absorbs both red and blue light. c. Chlorophyll a reflects green light. d. Different wavelengths of light have different energies. e. Chlorophyll a can be activated by absorbing a photon of light.
Answer: a
9. In cyclic photophosphorylation, chlorophyll is reduced by a. NADPH. b. a chemiosmotic mechanism. c. plastoquinone. d. ATP. e. hydrogen ions liberated by the splitting of a water molecule.
Answer: c
10. The energy difference between an electron excited by a photon and its ground state is a. less than the energy of the photon. b. greater than the energy of the photon. c. equal to the energy of the photon. d. related to the wavelength of the photon. e. Both c and d
Answer: e
11. 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 CO
2
from air is captured in a sugar.
Answer: c
12. Free energy is released in cyclic photophosphorylation a. by the formation of ATP. b. during the excitation of chlorophyll. c. during the fluorescence of chlorophyll. d. during each of the redox reactions of the electron transport chain. e. when electrons are transferred from photosystem I to photosystem II.
Answer: d
13. During cyclic photophosphorylation, the energy to produce ATP is provided by a. heat.

b. NADPH. c. ground-state chlorophyll. d. the redox reactions of the electron transport chain. e. the Calvin–Benson cycle.
Answer: d
14. In noncyclic photophosphorylation, water is used for the a. hydrolysis of ATP. b. excitation of chlorophyll. c. reduction of chlorophyll. d. oxidation of NADPH. e. synthesis of chlorophyll.
Answer: c
15. Photophosphorylation provides the Calvin–Benson cycle with a. protons and electrons. b. CO
2
and glucose. c. water and photons. d. light and chlorophyll. e. ATP and NADPH.
Answer: e
16. In noncyclic photophosphorylation, the chlorophyll in photosystem I is reduced by a. water. b. an electron from the transport chain of photosystem II. c. two photons of light. d. NADPH. e. ATP.
Answer: b
17. The enzyme ATP synthase couples the synthesis of ATP to a. the diffusion of protons. b. the reduction of NADP + . c. the excitation of chlorophyll. d. the reduction of chlorophyll. e. CO
2
fixation.
Answer: a
18–19. A suspension of algae is incubated in a flask in the presence of both light and
CO
2
. When it is transferred to the dark, the reduction of 3-phosphoglycerate to glyceraldehyde 3-phosphate is blocked.
18. Why does this reaction stop when the algae are placed in the dark? a. It requires CO
2
. b. It is an exergonic reaction. c. It requires ATP and NADPH + H
+
.

d. It requires O
2
. e. Chlorophyll is not synthesized in the dark.
Answer: c
19. When the reduction of 3-phosphoglycerate (3PG) to glyceraldehyde 3-phosphate
(G3P) is blocked, why does the concentration of ribulose bisphosphate (RuBP) decline? a. Ribulose bisphosphate is synthesized from glyceraldehyde 3-phosphate. b. Glyceraldehyde 3-phosphate is converted to glucose. c. Ribulose bisphosphate is used to synthesize 3-phosphoglycerate. d.
Both a and b e.
Both a and c
Answer: e
20. The enzyme rubisco is found in a. chloroplasts. b. mitochondria. c. the cytoplasm. d. the nucleus. e. yeast.
Answer: a
21. During CO
2
fixation, CO
2
combines with a. NADPH. b. 3PG. c. G3P. d. water. e. 1,5-ribulose bisphosphate.
Answer: e
22. How many moles of CO
2
must enter the Calvin–Benson cycle for the synthesis of one mole of glucose? a. 1 b. 2 c. 3 d. 6 e. 12
Answer: d
23. The NADPH required for the reduction of 3PG to G3P comes from a. the dark reactions. b. the light reactions. c. the synthesis of ATP. d. the Calvin–Benson cycle. e. oxidative phosphorylation.
Answer: b

24. In C
4
plants, the function of the four-carbon compound that is synthesized in the mesophyll cells is to a. reduce NADP + . b. combine with CO
2
to produce glucose. c. carry CO
2
to the bundle sheath cells. d. drive the synthesis of ATP. e. close the stomata.
Answer: c
25. In C
4
plants, starch grains are found in the chloroplasts of a. the thylakoids. b. mesophyll cells. c. the intracellular space. d. the stroma. e. bundle sheath cells.
Answer: e
26. During photorespiration, rubisco uses _______ as a substrate. a. CO
2 b. O
2 c. glyceraldehyde 3-phosphate d. 3-phosphoglycerate e. NADPH
Answer: b
27. Photorespiration starts in a. mitochondria. b. chloroplasts. c. C
4
plants only. d. the microbodies. e. the cytoplasm.
Answer: b
28. In plants, the reactions of glycolysis occur a. in C
3
plants only. b. in the mitochondria. c. in the chloroplasts. d. only in the presence of light. e. in the cytosol.
Answer: e
29. In both photosynthesis and respiration, protons are pumped across a membrane during a. electron transport. b. photolysis. c. CO
2
fixation. d. reduction of O
2
.

e. glycolysis.
Answer: a
30. The enzyme PEP carboxylase a. can trap CO
2
even at relatively low CO
2
concentrations. b. catalyzes the synthesis of RuBP. c. catalyzes the synthesis of 3PG. d. is found in the chloroplasts of bundle sheath cells. e. couples the synthesis of ATP to the diffusion of protons.
Answer: a
31. The function of photorespiration is a. CO
2
fixation. b. unknown. c. ATP production. d. the generating of a proton gradient. e. synthesis of glucose.
Answer: b
32. The NADPH required for CO
2
fixation is formed a. by the reduction of O
2
. b. by the hydrolysis of ATP. c. during the light reactions. d. in C
4
plants only. e. in the mitochondria.
Answer: c
33. The O
2
gas produced during photosynthesis is derived from a. CO
2
. b. glucose. c. water. d. carbon monoxide. e. bicarbonate ions.
Answer: c
34. 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
Answer: e
35. When a photon interacts with molecules such as those within chloroplasts, the photons may a. bounce off the molecules, having no effect.

b. pass through the molecules, having no effect. c. be absorbed by the molecules. d. Both a and c e. a, b, and c
Answer: e
36. Which of the following scientific tools “cracked” the Calvin–Benson cycle? a. Isotopes b. Paper chromatography c. Crystallography d. Centrifugation and electron microscopy e. Both a and b
Answer: e
37. In noncyclic photophosphorylation, electrons from which source replenish chlorophyll molecules that have given up electrons? a. CO
2 b. Water c. NADPH + H
+ d. O
2
gas e. None of the above
Answer: b
38. Which of the following biological groups is dependent on photosynthesis for its survival? a. Vertebrates b. Class Mammalia c. Fishes d. Both a and b e. a, b, and c
Answer: e
39. Photosynthesis is divided into two main phases, the first of which is a series of reactions that requires the absorption of photons. This phase is referred to as the a. reduction phase. b. dark reactions phase. c. carbon fixation phase. d. light reactions phase, or photophosphorylation. e. None of the above
Answer: d
40. The energy to hydrolyze water comes from a. oxidized chlorophyll. b. reduced chlorophyll. c. the proton gradient. d. ATP.

e. NADPH + H
+
.
Answer: a
41. Heterotrophs are dependent on autotrophs for their food supply. Autotrophs can make their own food by a. feeding on bacteria and converting the nutrients into usable energy. b. using light and simple chemicals to make reduced carbon compounds. c. synthesizing it from water and CO
2
. d. All of the above e. None of the above
Answer: b
42. Photosynthesis is the process that uses light energy to extract hydrogen atoms from which of the following sources? a. Glucose b. Chlorophyll c. CO
2 d. Water e. None of the above
Answer: d
43. Which of the following occurs during the dark reactions of photosynthesis? a. Water is converted into hydrogen and water. b. CO
2
is converted into sugars. c. Chlorophyll acts as an enzyme. d. Nothing occurs; the plant rests in the dark. e. None of the above
Answer: b
44. In bright light, the pH of the thylakoid space a. can become more acidic. b. can become more alkaline. c. stays the same; the pH of the thylakoid space never changes. d. can become neutral. e. None of the above
Answer: a
45. When a photon is absorbed by a molecule, what happens to the photon? a. It loses its ability to generate any energy. b. It raises the molecule from a ground state of low energy to an excited state. c. The exact relationship of the photon to the molecule is not clearly understood. d. It causes a change in the velocity of the wavelengths. e. None of the above
Answer: b

46. A range of energy that cannot be seen by human eyes, but which has slightly more energy per photon than visible light, is a. adaptive radiation. b. solar radiation. c. gamma radiation. d. ultraviolet radiation. e. None of the above
Answer: d
47. The main photosynthetic pigments in plants are a. chlorophyll s and chlorophyll a . b. chlorophyll x and chlorophyll y . c. retinal pigment and accessory pigment. d. chlorophyll a and chlorophyll b . e. None of the above
Answer: d
48. Compared to long wavelength photons, short-wavelength photons have a. an insignificant amount of energy. b. more energy. c. energy not available to plant cells. d. a ladder of energy. e. an equal amount of energy.
Answer: b
49. The chemiosmotic hypothesis states that the energy for the production of ATP comes from a. the transfer of phosphate from intermediate compounds. b. the reduction of NADP. c. a proton gradient set up across the thylakoid membrane. d. the oxidation of CO
2
. e. Both a and b
Answer: c
50. When CO
2
is added to RuBP, the first stable product synthesized is a. pyruvate. b. glyceraldehyde 3-phosphate. c. phosphoglycerate. d. ATP. e. Both a and b
Answer: c
51. Photosynthesis takes place in plants only in the light. Respiration takes place a. in the dark only. b. in the light only. c. in all organisms except for plants.

d. both with and without light. e. None of the above
Answer: d
52. The revised, balanced equation for the generation of sugar from sunlight, water, and
CO
2
is a. 6 CO
2
+ 6 H
2
O → C
6
H
12
O
6
+ O
2
. b. 6 CO
2
+ 12 H
2
O → C
6
H
12
O
6
+ 6 O
2
+ 6 H
2
O. c. 6 CO
2
+ 6 H
2
O →C
6
H
12
O
6
+ 6 O
2
. d. 12 CO
2
+ 12 H
2
O →2 C
6
H
12
O
6
+ 2 O
2
. e. None of the above
Answer: b
53. The net energy outcome of cyclic photophosphorylation is a. ATP. b. ATP and NADH. c. NADPH. d. ATP and NADPH. e. sugar.
Answer: a
54. The concentration of O
2
in the air is _______ percent. a. 70 b. 21 c. 2.1 d. 0.21 e. 0.02
Answer: b
55. In C
4
plants, CO
2
is first fixed into a compound called a. pyruvate. b. glucose. c. oxaloacetate. d. ribulose bisphosphate. e. 3-phosphoglycerate.
Answer: c
56. In cacti, CO
2
is stored for use in the Calvin–Benson cycle a. in the stems, roots, and leaves. b. during the evening. c. in glucose molecules. d. in the stroma. e. Both a and d
Answer: b
57. Plants classified as CAM store CO
2

a. by making oxaloacetate. b. by making PEP carboxylase. c. in malic acid. d. in crassulacean acid. e. Both a and c
Answer: e
58. Which of the following statements about photosynthesis is false ? a. The water for photosynthesis in land plants comes primarily from the soil. b. CO
2
is taken in, and water and O
2
are released through stomata. c. Light is absolutely necessary for the production of O
2
and carbohydrates. d. Photosynthesis is the reverse of cellular respiration. e. All the O
2
gas produced during photosynthesis comes from water.
Answer: d
59. What is the difference between chlorophyll a and chlorophyll b ? a. Chlorophyll a has a complex ring structure whereas chlorophyll b has a linear structure. b. Chlorophyll a has a magnesium atom at its center whereas chlorophyll b has a phosphate group at its center. c. Chlorophyll a has a methyl group whereas chlorophyll b has an aldehyde group. d. A hydrocarbon tail is found only in chlorophyll a . e. Chlorophyll a fluoresces whereas chlorophyll b passes the absorbed energy to another molecule.
Answer: c
60. The energy source for the synthesis of carbohydrates in the Calvin–Benson cycle is a. ATP only. b. photons. c. energized chlorophyll a . d. NADPH + H
+
. e. NADPH + H
+
and ATP only.
Answer: e
61. Cyclic electron transport a. occurs when the ratio of NADPH + H
+
to NADP
+
in the chloroplasts of some organisms is high. b. is a series of redox reactions. c. stores its released energy as a proton gradient. d. is completed when the electron returns to P
700
+ . e. All of the above
Answer: e
62. How does rubisco “decide” whether to act as an oxygenase or a carboxylase? a. Rubisco has 10 times more affinity for O
2
than CO
2
; therefore, it favors O
2
fixation. b. If O
2
is relatively abundant, rubisco acts as a carboxylase.

c. If O
2
predominates, rubisco fixes it and the Calvin-Benson cycle occurs. d. Photorespiration is more likely at low temperatures. e. As the ratio of CO
2
to O
2
falls in the leaf, the reaction of rubisco with O
2
is favored and photorespiration proceeds.
Answer: e
63. When RuBP reacts with O
2
, a. it cannot react with CO
2
. b. carbohydrate production increases. c. plant growth is stimulated. d. net carbon fixation increases by 25 percent. e. two carbon molecules combine to form the four-carbon phosphoglycolate.
Answer: a
64. Photosynthesis and respiration are linked through the a. Calvin–Benson cycle. b. the citric acid cycle. c. glycolysis. d. Both a and c e. a, b, and c
Answer: e
65. What happens when a photon is absorbed by chlorophyll? a. Chlorophyll becomes “excited,” or energized. b. A greater number of light wavelengths can be absorbed. c. ATP is split into ADP, phosphate, and energy. d. Hydrogen ions are released. e. The chlorophyll molecules fluoresce.
Answer: a
Knowledge and Synthesis Questions
1. The main purpose of photosynthesis is to a. consume CO
2
. b. produce ATP. c. convert light energy to chemical energy. d. produce starch.
2. Which of the following best represent the components that are necessary for photosynthesis to take place? a. Mitochondria, accessory pigments, visible light, water, and CO
2 b. Chloroplasts, accessory pigments, visible light, water, and CO
2 c. Mitochondria, chlorophyll, visible light, water, and O
2

d. Chloroplasts, chlorophyll, visible light, water, and CO
2
3. Chlorophyll is suited for the capture of light energy because a. certain wavelengths of light raise it to an excited state. b. in its excited state chlorophyll gives off electrons. c. chlorophyll’s structure allows it to attach to thylakoid membranes. d. All of the above
4. Plants give off O
2
because a. O
2
results from the incorporation of CO
2
into sugars. b. plants do not respire because they photosynthesize. c. water is the initial proton donor, leaving O
2
as a photosynthetic by-product. d. All of the above
5. Cyclic and noncyclic electron flow are used in plants to a. meet the ATP demands of the Calvin–Benson cycle. b. avoid producing excess NADPH + H
+
. c. balance ATP and NADPH + H
+
ratios in the chloroplast. d. All of the above
6. Which of the following statements concerning the light reactions of photosynthesis is true? a. Photosystem I can operate independently of photosystem II. b. Photosystems I and II are activated by different wavelengths of light. c. Photosystems I and II transfer electrons and create proton gradients across the thylakoid membrane. d. All of the above
7. ATP is produced during the light reactions via a. CO
2
fixation. b. chemiosmosis. c. reduction of water. d. All of the above
8. Because of the properties of chlorophyll, plants need adequate __________ light to grow properly. a. green b. blue and red c. infrared d. ultraviolet
9. Which of the following statements concerning the Calvin–Benson cycle is not true? a. Light energy is not required for the cycle to proceed. b. CO
2
is assimilated into sugars. c. RuBP is regenerated. d. It uses energy stored in ATP and NADPH + H
+
.

10. Which of the following statements concerning rubisco is true? a. Rubisco is an enzyme. b. Rubisco catalyzes both the beginning steps of photorespiration and the Calvin–Benson cycle. c. Rubisco is the most abundant protein on earth. d. All of the above
11. Which of the following begins the Calvin–Benson cycle and is the commitment step that results in the entire pathway being carried out? a. 3PG is reduced to G3P using ATP and NADPH + H
+
. b. RuBP is regenerated. c. CO
2
and RuBP join forming 3PG. d. As a cycle, it can start at any point.
12. The Calvin–Benson Cycle results in the production of a. glucose. b. starch. c. rubisco. d. G3P.
13. Which of the following statements regarding photorespiration is true? a. Photorespiration is a metabolically expensive pathway. b. Photorespiration is avoided when CO
2
is abundant. c. Photorespiration reduces the overall CO
2
that is converted to carbohydrates. d. All of the above
14. The fixation of CO
2
by PEP carboxylase functions to a. concentrate CO
2
for use in photosynthetic cells. b. allow plants to close stomata without having photorespiration occur. c. allow plants to photosynthesize in the dark. d. Both a and b
15. CAM plants differ from C
4
plants in that a. CO
2
is stored as malic acid. b. photosynthesis can occur at night in these plants. c. their stomata close during periods that favor photorespiration. d. they use PEP carboxylase to fix CO
2
.
16. Which of the following statements is true regarding the relationship between photosynthesis and cellular respiration in plants? a. Photosynthesis occurs in specialized photosynthetic cells. b. Cellular respiration occurs in specialized respiratory cells. c. Cellular respiration and photosynthesis can occur in the same cell. d. Both a and c
Answers

Knowledge and Synthesis Questions
1.
c.
Photosynthetic organisms are the only life forms capable of trapping light energy and converting it to chemical energy. Because of this they form the basis of food chains.
2.
d.
Chloroplasts are the site of the photosynthetic reactions; chlorophyll is excited by photons of light and serve as reaction centers for the photosystems; visible light is necessary to excite chlorophyll and accessory pigments; water is the initial electron donor for the pathway; and CO
2
is necessary to make precursor molecules for energy storage.
3.
d.
The “tails” of chlorophyll molecules are associated with the thylakoid membranes of the chloroplasts. This close membrane association assists with establishing the protonmotive force that will drive ATP synthesis. When excited by light, the chlorophyll moves into an excited state and passes electrons to acceptor molecules. This begins to set up the proton gradient across the membrane that will drive ATP synthesis.
4. c.
Water is split at photosystem II to donate electrons to the reaction center. The resulting protons are moved across the membrane to establish the proton-motive force and O
2
is given off as a by-product.
5.
d. ATP is required at higher levels in the Calvin–Benson cycle than NADPH + H
+
is; therefore, there must be a mechanism for producing additional ATP. Cyclic electron flow provides that mechanism. If noncyclic electron flow were to be sped up to meet ATP needs, an excess of NADPH + H
+
would result. Shifting between cyclic and noncyclic flow balances ATP/NADPH + H
+
ratios.
6. d.
Photosystems I and II operate depending on whether electron flow is cyclic or noncyclic. Activity is controlled by the ATP levels in the chloroplast. Photosystem II is activated by light of a higher energy level than photosystem I. Both photosystems transfer electrons and create proton gradients across the thylakoid membranes.
7.
b.
In the light reactions, ATP synthesis occurs when protons flow through an ATP synthase channel protein in the thylakoid membrane. This is a chemiosmotically driven process.
8.
b.
Chlorophyll and accessory pigments absorb light in the blue and orange-red wavelengths of visible light. Green light is reflected; therefore, plants appear green.
9. a.
Light energy is required for the Calvin–Benson cycle to proceed. ATP synthesis is dependent on light energy, and the Calvin–Benson cycle is dependent on ATP.
10.
d.
Rubisco, the most abundant enzyme on earth, has both oxygenase and carboxylase activities.
11.
c.
The first step of the Calvin–Benson cycle is the fixation of CO
2
into 3PG. This is the regulatory step, and it requires ATP and NADPH + H
+
.

12.
d.
The Calvin–Benson cycle produces only G3P. G3P can then be metabolized into storage products like sugars and starch.
13.
d.
Photorespiration uses as much ATP as photosynthesis, but results in no energy gains for the plant and reduces net carbon fixation by 25 percent compared with the
Calvin–Benson cycle. If CO
2
is abundantly available, rubisco acts as a carboxylase rather than an oxygenase.
14. d.
Plants do not photosynthesize in the dark. PEP carboxylase allows the fixation of
CO
2
and the concentration of it at rubisco.
15.
a.
CAM plants functionally store CO
2
as malic acid.
16.
d.
Photosynthesis occurs only in cells that have the necessary structures, but cellular respiration occurs in every living cell.
1. In noncyclic photosynthetic electron transport, water is used to a. excite chlorophyll. b. hydrolyze ATP. c. reduce chlorophyll. d. oxidize NADPH. e. synthesize chlorophyll.
2. 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.
3. Which statement about chlorophylls is not true? a. They absorb light near both ends of the visible spectrum. b. They can accept energy from other pigments, such as carotenoids. c. Excited chlorophyll can either reduce another substance or fluoresce. d. Excited chlorophyll may be an oxidizing agent. e. They contain magnesium.
4. In cyclic electron transport, a. oxygen gas is released. b. ATP is formed. c. water donates electrons and protons. d. NADPH + H
+
forms.

e. CO
2
reacts with RuBP.
5. 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 + H
+
forms. e. CO
2
reacts with RuBP.
6. In the chloroplasts, a. light leads to the pumping of protons out of the thylakoids. b. ATP forms when protons are pumped into the thylakoids. c. light causes the stroma to become more basic than the thylakoids. d. protons return passively to the stroma through protein channels. e. proton pumping requires ATP.
7. Which statement about the Calvin–Benson cycle is not true? a. CO
2
reacts with RuBP to form 3PG. b. RuBP forms by the metabolism of 3PG. c. ATP and NADPH + H
+
form when 3PG is reduced. d. The concentration of 3PG rises if the light is switched off. e. Rubisco catalyzes the reaction of CO
2
and RuBP.
8. In C
4
photosynthesis, a. 3PG is the first product of CO
2
fixation. b. rubisco catalyzes the first step in the pathway. c. four-carbon acids are formed by PEP carboxylase in bundle sheath cells. d. photosynthesis continues at lower CO
2
levels than in C
3
plants. e. CO
2
released from RuBP is transferred to PEP.
9. 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.
10. Photorespiration a. takes place only in C
4
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.
Answers

1. c
2. b
3. d
4. b
5. e
6. c
7. c
8. d
9. d
10. b
1.The overall reaction CO
2
+ H
2
O + NADPH + ATP → sugar + NADP + ADP + P a.describes the light reactions of photosynthesis. b.is exergonic. c.occurs only at night. d.requires many enzymes. e.occurs only in the thylakoid membranes.
Answer: d
2.The light reactions of photosynthesis a.convert light energy into chemical energy. b.occur in all plant and animal cells. c.occur only at night. d.occur in both chloroplasts and mitochondria. e.produce ADP from ATP.
Answer: a
3.Which statement about accessory pigments is not true? a.Phycobilins absorb yellow-green, yellow and orange wavelengths. b.Accessory pigments absorb photons intermediate in energy between the red and blue wavelengths. c.Accessory pigments absorb blue and red wavelengths. d.Carotenoids absorb photons in the blue and blue-green wavelengths and appear deep yellow. e.Accessory pigments transfer a portion of energy to chlorophylls.
Answer: c
4.In noncyclic electron flow, a.light energy is used to reduce water. b.ATP and NADPH + H
+
is formed. c.only NADPH + H
+
is formed. d.only ATP is formed. e.water is split to transfer oxygen to chlorophyll.

Answer: b
5.The chemical source of molecular oxygen O
2
in photosynthesis is a.CO
2.
b.C
6
H
12
O
6.
c.H
2
O. d.NADP. e.chlorophyll.
Answer: c
6.The NADPH required for CO
2
fixation is formed a.by the reduction of oxygen. b.by the hydrolysis of ATP. c.during photosystem I in noncyclic photosynthesis. d.only in C
4
plants. e.in the mitochondria.
Answer: c
7.Which of the following is not a process of the Calvin–Benson Cycle? a.For every "turn" of the cycle, with one CO
2
fixed, the CO
2
acceptor is regenerated. b.CO
2
combines with RuMP forming 3PG. c.One-sixth of the G3P is used to make sugars. d.Five-sixths is processed in the complex reactions that produce RuMP. e.3PG is reduced to G3P in a two-step reaction requiring ATP and NADPH + H
+
.
Answer: b
8.In C
3
photosynthesis, a.PEP is the primary CO
2
acceptor. b.there are two classes of chloroplasts. c.the photosynthetic cells of the leaf are mesophyll and bundle sheath. d.there can be extensive photorespiration. e.the first product of CO
2
fixation is a 4-carbon compound.
Answer: d
9.Light reactions and the Calvin–Benson cycle occur in the a.stroma. b.chloroplasts. c.cell wall. d.mitochondria. e.thykaloids.
Answer: e
10.Which of the following is true of photorespiration? a.It takes place only in C
4
plants. b.It includes reactions carried out in peroxisomes. c.It increases the yield of photosynthesis.

d.It is catalyzed by PEP carboxylase. e.It is independent of light intensity.
Answer: b
11.Movement of hydrogen ions through the ATP synthetase pore fuels the later stages of photosynthesis. a. true b. false
Answer: a
12.Which of the following statements concerning photophosphorylation is false? a. In the electron transport chain, electrons are passed through electron carriers via redox reactions. b. Pigment molecules capture energy until the energy reaches a chlorophyll molecule. c. Plastoquinone is reduced and cytochrome is oxidized when electrons move from one to the other. d. NADP reductase reduces NADP+, producing NADPH and H+. e. The reaction center is where light energy from a photon is absorbed and transferred to a chlorophyll molecule.
Answer: c
13.Chloroplasts a. contain thylakoids, which are flattened sacs with chlorophyll inside. b. are found in the mitochondria. c. are found in both animal and plant cells. d. are found only in plant cells. e. a and d.
Answer: e
14.During cyclic photophosphorylation, which is (are) reduced using excited electrons form chlorophyll? a. P 680 b. NADP c. P 690 d. water e. None of the above
Answer: e
15.The excited electrons that are removed from chlorophyll may be used to reduce a. NADP. b. water. c. oxygen. d. ATP. e. glucose.
Answer: b