Raven/Johnson Biology 8e
Chapter 8
1. The light-dependent reactions of photosynthesis are responsible for the production of—
a. glucose
b. CO2
c. ATP and NADPH
d. H2O
The correct answer is c—
A. Answer a is incorrect. Glucose is a product of the Calvin cycle. The reactions that make
up the Calvin cycle depend on the ATP and NADPH produced during the light reactions,
but they can occur in the absence of light.
The correct answer is c—
B. Answer b is incorrect. CO2 is associated with the process of carbon fixation that occurs
during the Calvin cycle. CO2 is consumed, not produced. CO2 production is a property of
cellular respiration.
The correct answer is c—ATP and NADPH
C. Answer c is correct. The energy captured from sunlight is used to generate ATP and
NADPH.
The correct answer is c—
D. Answer d is incorrect. H2O is a product of cellular respiration. During the light reactions
of photosynthesis water is used as an electron and proton donor; it is not produced.
2. Which region of a chloroplast is associated with the capture of light energy?
a. Thylakoid membrane
b. Outer membrane
c. Stroma
d. Both a and c
The correct answer is a—Thylakoid membrane
A. Answer a is correct. The pigment molecules responsible for capturing light are embedded
in the thylakoid membrane.
The correct answer is d—
B. Answer b is incorrect. The outer membrane surrounds the entire organelle but does not
have any of the light-harvesting pigments.
The correct answer is d—
C. Answer c is incorrect. The stroma is the region of the chloroplast that is involved with the
Calvin cycle. It is a compartment that holds the enzymes used in the reactions of carbon
fixation.
The correct answer is d—Both a and c
D. Answer d is incorrect. Option c is incorrect, therefore both cannot be correct.
3. The colors of light that are most effective for photosynthesis are—
a. red, blue, and violet
b. green, yellow, and orange
Raven/Johnson Biology 8e
Chapter 8
c. infrared and ultraviolet
d. all colors of light are equally effective
The correct answer is a—red, blue, and violet
A. Answer a is correct. The pigments associated with photosynthesis specifically absorb light
energy in the wavelengths that correspond to red, blue, and violet light.
The correct answer is a—
B. Answer b is incorrect. These colors are reflected by photosynthetic pigments. Reflected
light is not used in photosynthesis. Light energy must be absorbed to be used in
photosynthesis.
The correct answer is a—
C. Answer c is incorrect. Energy at these two extremes of the spectrum is outside the range
of the photosynthetic pigments. Photosynthetic pigments absorb light within the visible
range.
The correct answer is a—
D. Answer d is incorrect. Photosynthetic pigments have characteristic absorption spectra that
correspond to the chemical properties of each pigment.
4. The colors associated with pigments such as chlorophyll or carotenoids are a product of—
a. the wavelengths of light absorbed by the pigment
b. the wavelengths of light reflected by the pigment
c. the energy transferred between pigments
d. the wavelengths of light emitted by the pigment
The correct answer is b—
A. Answer a is incorrect. When a wavelength of light is absorbed, its energy is transferred to
the pigment molecule and is no longer visible.
The correct answer is b—the wavelengths of light reflected by the pigment
B. Answer b is correct. Reflected light is the “leftover” wavelengths of light that are not
absorbed by the photosynthetic pigments.
The correct answer is b—
C. Answer c is incorrect. The energy transferred between the pigment molecules in a
photosystem is in the form of electrons, not photons.
The correct answer is b—
D. Answer d is incorrect. Pigments within a chloroplast function to absorb light energy, not
give it off.
5. Which of the following best describes a photosystem?
a. A collection of pigment molecules
b. A collection of pigments that transfer energy captured from light to a reaction
center pigment
c. A collection of thylakoid membranes assembled into a structure called a granum
Raven/Johnson Biology 8e
Chapter 8
d. A collection of chlorophyll molecules that capture light energy and use it to make
ATP
The correct answer is b—
A. Answer a is incorrect. Photosystems are made up of pigment molecules; however, these
molecules function as a unit to transfer light energy to a central reaction center pigment.
The correct answer is b—A collection of pigments that transfer energy captured from light to a
reaction center pigment
B. Answer b is correct. The pigments that make up the antenna complex capture light
energy and transfer it in the form of excitation energy to the reaction center chlorophyll.
The correct answer is b—
C. Answer c is incorrect. Photosystems are composed of pigment molecules embedded in the
membrane of the thylakoid. Multiple photosystems exist on a single thylakoid.
The correct answer is b—
D. Answer d is incorrect. A photosystem is composed of pigment molecules that capture
energy; however, the production of ATP occurs through the activity of an electron
transport chain and the enzyme ATP synthase.
6. How is a reaction center pigment different from a pigment in the antenna complex?
a. The reaction center pigment is a chlorophyll molecule.
b. The antenna complex pigment can only reflect light.
c. The reaction center pigment loses an electron when it absorbs light energy.
d. The antenna complex pigments are not attached to proteins.
The correct answer is c—
A. Answer a is incorrect. The antenna complex is made up of chlorophyll and other
pigments.
The correct answer is c—
B. Answer b is incorrect. The antenna complex pigments function by absorbing light energy.
The correct answer is c—The reaction center pigment loses an electron when it absorbs light
energy.
C. Answer c is correct. While the antenna complex pigments transfer excitation energy, the
reaction center pigment loses its excited electron and becomes oxidized.
The correct answer is c—
D. Answer d is incorrect. Both the reaction center pigment and the antenna complex
pigments are organized by a protein scaffold in the membrane of the thylakoid.
7. What happens to the energy from an excited reaction center electron in the cyclic
photophosphorylation of sulfur bacteria?
a. It is used to make ATP.
b. It is used to phosphorylate proteins in an electron transport chain.
c. It is used to generate a new pigment molecule.
d. It is used to excite another pigment molecule within the photosystem.
Raven/Johnson Biology 8e
Chapter 8
The correct answer is a—It is used to make ATP.
A. Answer a is correct. The excited electron is transferred to an electron transport chain that
leads to the production of ATP. The electron is eventually returned to the reaction center
pigment from which it came.
The correct answer is a—
B. Answer b is incorrect. The movement of the electron through an electron transport chain
drives a proton pump, leading to the creation of a proton gradient. Only ADP can be said
to become phosphorylated.
The correct answer is a—
C. Answer c is incorrect. The energy from the excited electron is used to make ATP, not
pigment molecules.
The correct answer is a—
D. Answer d is incorrect. Only the reaction center pigment is capable of donating its
electron. The transfer of energy between pigments occurs with other pigments within the
antenna complex.
8. During noncylic photosynthesis, photosystem I functions to ____________, and
photosystem II functions to ______________.
a. synthesize ATP; produce O2
b. reduce NADP+; oxidize H2O
c. reduce CO2; oxidize NADPH
d. restore an electron to its reaction center; gain an electron from water
The correct answer is b—
A. Answer a is incorrect. Photosystem I only makes ATP during cyclic photosynthesis. O2
production is associated with photosystem II.
The correct answer is b— reduce NADP+; oxidize H2O
B. Answer b is correct. Photosystem I transfers electrons to NADPH, and these electrons are
replaced with electrons from photosystem II. Photosystem II is able to oxidize H2O to
replace electrons transferred to photosystem I via an electron transport chain.
The correct answer is b—
C. Answer c is incorrect. The reduction of CO2 and the oxidation of NADPH is associated
with carbon fixation in the Calvin cycle.
The correct answer is b—
D. Answer d is incorrect. Photosystem I only recycles its electrons to its reaction center
during cyclic photosynthesis. Photosystem II replace its reaction center pigment by
splitting water.
9. Where in a chloroplast would you find the highest concentration of protons?
a. In the stroma
b. In the lumen of the thylakoid
c. In the intermembrane space
Raven/Johnson Biology 8e
Chapter 8
d. In the antenna complex
The correct answer is b—
A. Answer a is incorrect. The stroma provides a source of hydrogen ions; however, protons
are accumulated in the lumen of the thylakoid.
The correct answer is b—In the lumen of the thylakoid
B. Answer b is correct. The electron transport chain found on the thylakoid membrane
functions to pump hydrogen ions into the lumen of the thylakoid.
The correct answer is b—
C. Answer c is incorrect. The intermembrane space is found in a mitochondrion, not a
chloroplast.
The correct answer is b—
D. Answer d is incorrect. The antenna complex is composed of pigment molecules and does
not interact with hydrogen ions.
10. How does the reaction center of photosystem I regain an electron during noncyclic
photosynthesis?
a. The electron is recycled directly back to the reaction center pigment.
b. The electron is donated from H2O.
c. The electron is donated from photosystem II.
d. The electron is donated from NADPH.
The correct answer is c—
A. Answer a is incorrect. Electrons are recycled during cyclic not noncyclic photosynthesis.
During noncyclic photosynthesis the electron from photosystem I is used to reduce
NADP+ to NADPH.
The correct answer is c—
B. Answer b is incorrect. H2O is used to replace the electron lost from photosystem II.
The correct answer is c—The electron is donated from photosystem II.
C. Answer c is correct. The electron from photosystem II moves through the electron
transport chain and is finally accepted by the reaction center pigment of photosystem I.
The correct answer is c—
D. Answer d is incorrect. Photosystem I donates its electron to NADPH. NADPH is then
used in the Calvin cycle to help reduce CO2.
11. Which of the following is NOT associated with the thylakoid membrane?
a. Photosystem II
b. ATP synthase
c. Rubisco
d. B6-f complex
The correct answer is c—
Raven/Johnson Biology 8e
Chapter 8
A. Answer a is incorrect. Photosystem II is made of up a complex of pigment molecules
embedded in the thylakoid membrane.
The correct answer is c—
B. Answer b is incorrect. The ATP synthase enzyme is located in the thylakoid membrane
where it converts ADP to ATP using the movement of hydrogen ions down their
concentration gradient.
The correct answer is c—Rubisco
C. Answer c is correct. Rubisco is the key enzyme involved in the first step of the Calvin
cycle. The Calvin cycle occurs within the stroma of the chloroplast.
The correct answer is c—
D. Answer d is incorrect. The b6-f complex is part of the electron transport chain found in the
thylakoid membrane.
12. Carbon fixation occurs when a molecule of CO2 reacts with a molecule of—
a. ribulose 1,5-bisphosphate (RuBP)
b. glyceraldehydes-3-phosphate (G3P)
c. 3-phosphoglycerate (PGA)
d. pyruvate
The correct answer is a—ribulose 1,5-bisphosphate (RuBP)
A. Answer a is correct. The first step of the Calvin cycle involves the formation of a covalent
bond between CO2 and RuBP.
The correct answer is a—
B. Answer b is incorrect. G3P is the product of carbon fixation.
The correct answer is a—
C. Answer c is incorrect. PGA is the product of the reaction of CO2 with RuBP.
The correct answer is a—
D. Answer d is incorrect. Pyruvate is not associated with photosynthesis.
13. The function of the Calvin cycle is to—
a. absorb light energy
b. synthesize RuBP
c. fix carbon
d. convert glucose to CO2, yielding energy
The correct answer is c—
A. Answer a is incorrect. The reactions of the Calvin cycle require the products of the light
reaction, but do not use light directly.
The correct answer is c—
B. Answer b is incorrect. RuBP is the key intermediate, and the last part of the cycle
involves regenerating RuBP, but the cycle functions to fix carbon.
Raven/Johnson Biology 8e
Chapter 8
The correct answer is c—fix carbon
C. Answer c is correct. The function of the Calvin cycle is to convert CO2 into useful organic
molecules. That is a description of carbon fixation.
The correct answer is c—
D. Answer d is incorrect. CO2 is consumed in the process of carbon fixation.
14. What is photorespiration?
a. The production of chemical energy (ATP) using light energy (photons).
b. Carbon fixation using the energy gained from the light reactions of
photosynthesis.
c. The use of O2 by plants as a final electron acceptor for photosynthesis.
d. The addition of O2 to RuBP leading to the loss of CO2 and ATP.
The correct answer is d—
A. Answer a is incorrect. The production of chemical energy from light energy describes the
light reactions of photosynthesis.
The correct answer is d—
B. Answer b is incorrect. The Calvin cycle uses the ATP and NADPH energy from the light
reactions of photosynthesis to fix carbon.
The correct answer is d—
C. Answer c is incorrect. The pigment molecules function as electron acceptors in
photosynthesis.
The correct answer is d— The addition of O2 to RuBP leading to the loss of CO2 and ATP.
D. Answer d is correct. Photorespiration is a wasteful reaction that uses ATP energy and
releases CO2 as a by-product.
15. The adaptation of fixing CO2 from the atmosphere at night is characteristic of—
a. C3 plants
b. C4 plants
c. CAM plants
d. all of the above
The correct answer is c—
A. Answer a is incorrect. C3 plants are not adapted to prevent photorespiration.
The correct answer is c—
B. Answer b is incorrect. C4 plants have adapted to photorespiration by separating the
process of carbon fixation and the Calvin cycle into different cells.
The correct answer is c—CAM plants
C. Answer c is correct. CAM plants only open their stomata at night and accumulate CO2 in
the form of oxaloacetate.
The correct answer is c—
D. Answer d is incorrect. Only CAM plants are adapted to fix carbon at night.
Raven/Johnson Biology 8e
Chapter 8
Challenge Questions
1. Study the process the Calvin cycle diagrammed in Figure 8.16. Where do the ATP and
NADPH used in this reaction come from? How can a chloroplast generate enough ATP to
support the needs of the Calvin cycle?
Answer—The ATP and NADPH are generated during the noncyclic light reactions of
photosynthesis. This figure illustrates that the Calvin cycle requires more ATP than NADPH.
Additional ATP can be generated through cyclic photosynthesis using only photosystem I.
2. Compare the process of photosynthesis in green plants and sulfur bacteria.
Answer—Similarities
Both use pigments to capture light.
Both use photosystems.
Differences
Types of pigments differ.
Chlorophyll a vs bacteriochlorophyll a.
Plants produce O2, bacteria do not.
Plants use chloroplasts, bacteria have
no separate organelles, just highly
folded plasma membrane.
Some bacteria have a single photosystem,
whereas plants have two.
Light energy causes the movement
of an electron along an electron transport chain.
Both can use cyclic photosynthesis.
Sulfur bacteria split hydrogen sulfide, in
plants, water is split.
3. Do plant cells need mitochondria? Explain your answer.
Answer—Yes. Plants use their chloroplast to convert light energy into chemical energy. During
light reactions ATP and NADPH are created, but these molecules are consumed during the
Calvin cycle and are not available for the cell’s general use. The G3P produced by the Calvin
cycle stores the chemical energy from the light reactions within its chemical bonds. Ultimately,
this energy is stored in glucose and retrieved by the cell through the process of glycolysis and
cellular respiration.