Campbell’s Biology, 9e (Reece et al.)
Chapter 10 Photosynthesis
Students find this chapter quite challenging. Fortunately, some of the key concepts, such as
chemiosmosis and redox, were discussed previously in the chapter on respiration and fermentation. The
new key concepts are light as energy, light absorption and energy conversion by pigments, and linear
and cyclic electron flow. Students are challenged to identify the relationships between the light reactions
and the Calvin cycle, as well as the adaptive significance of C4 and CAM pathways. Comparison and
contrast between photosynthesis and respiration, the significance of photosynthesis to Earth history and
evolution of life, and the role of photosynthesis in global carbon cycles and environmental change are
important topics to engage students.
Multiple-Choice Questions
1) If photosynthesizing green algae are provided with CO2 synthesized with heavy oxygen (18O), later
analysis will show that all but one of the following compounds produced by the algae contain the 18O
label. That one is
A) 3-phosphoglycerate.
B) glyceraldehyde 3-phosphate (G3P).
C) glucose.
D) ribulose bisphosphate (RuBP).
E) O2.
2) 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, i, and NADP+
D) electrons and H+
E) ATP and NADPH
3) Photosynthesis is not responsible for
A) oxygen in the atmosphere.
B) the ozone layer.
C) most of the organic carbon on Earth’s surface.
D) atmospheric CO2.
E) fossil fuels.
4) Where does the Calvin cycle take place?
A) stroma of the chloroplast
B) thylakoid membrane
C) cytoplasm surrounding the chloroplast
D) interior of the thylakoid (thylakoid space)
E) outer membrane of the chloroplast
5) In any ecosystem, terrestrial or aquatic, what group(s) is (are) always necessary?
A) autotrophs and heterotrophs
B) producers and primary consumers
C) photosynthesizers
D) autotrophs
E) green plants
6) In autotrophic bacteria, where are the enzymes located that can carry on carbon fixation (reduction of
carbon dioxide to carbohydrate)?
A) in chloroplast membranes
B) in chloroplast stroma
C) in the cytosol
D) in the nucleoid
E) in the infolded plasma membrane
7) When oxygen is released as a result of photosynthesis, it is a direct by-product of
A) reducing NADP+.
B) splitting water molecules.
C) chemiosmosis.
D) the electron transfer system of photosystem I.
E) the electron transfer system of photosystem II.
8) 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) red and yellow
B) blue and violet
C) green and yellow
D) blue, green, and red
E) green, blue, and yellow
9) Halobacterium has a photosynthetic membrane that is colored purple. Its photosynthetic action
spectrum is exactly complementary (opposite to) the action spectrum for green plants. What
wavelengths of light do the Halobacterium photosynthetic pigments absorb?
A) red and yellow
B) blue, green, and red
C) green and yellow
D) red and green
E) blue and red
10) In the thylakoid membranes, what is the main role of the antenna pigment molecules?
A) split water and release oxygen to the reaction-center chlorophyll
B) harvest photons and transfer light energy to the reaction-center chlorophyll
C) synthesize ATP from ADP and i
D) transfer electrons to ferredoxin and then NADPH
E) concentrate photons within the stroma
11) Which of the events listed below occurs in the light reactions of photosynthesis?
A) NADP is produced.
B) NADPH is reduced to NADP+.
C) Carbon dioxide is incorporated into PGA.
D) ATP is phosphorylated to yield ADP.
E) Light is absorbed and funneled to reaction-center chlorophyll a.
12) Which statement describes the functioning of photosystem II?
A) Light energy excites electrons in the thylakoid membrane electron transport chain.
B) Photons are passed along to a reaction-center chlorophyll.
C) The P680 chlorophyll donates a pair of protons to NADP+, which is thus converted to NADPH.
D) The electron vacancies in P680+ are filled by electrons derived from water.
E) The splitting of water yields molecular carbon dioxide as a by-product.
13) Which of the following are directly associated with photosystem I?
A) harvesting of light energy by ATP
B) receiving electrons from the thylakoid membrane electron transport chain
C) generation of molecular oxygen
D) extraction of hydrogen electrons from the splitting of water
E) passing electrons to the thylakoid membrane electron transport chain
14) 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 determine if they have thylakoids in the chloroplasts.
B) to test for liberation of O2 in the light.
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.
15) What are the products of linear photophosphorylation?
A) heat and fluorescence
B) ATP and P700
C) ATP and NADPH
D) ADP and NADP
E) P700 and P680
16) 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) photosystem II
B) photosystem I
C) cyclic electron flow
D) linear electron flow
E) chlorophyll
17) 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 splitting of water
B) the absorption of light energy by chlorophyll
C) the flow of electrons from photosystem II to photosystem I
D) the synthesis of ATP
E) the reduction of NADP+
18) What does the chemiosmotic process in chloroplasts involve?
A) establishment of a proton gradient across the thylakoid membrane
B) diffusion of electrons through the thylakoid membrane
C) reduction of water to produce ATP energy
D) movement of water by osmosis into the thylakoid space from the stroma
E) formation of glucose, using carbon dioxide, NADPH, and ATP
19) 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) The isolated chloroplasts will make ATP.
B) The Calvin cycle will be activated.
C) Cyclic photophosphorylation will occur.
D) The isolated chloroplasts will generate oxygen gas.
E) The isolated chloroplasts will reduce NADP+ to NADPH.
20) In a plant cell, where are the ATP synthase complexes located?
A) thylakoid membrane only
B) plasma membrane only
C) inner mitochondrial membrane only
D) thylakoid membrane and inner mitochondrial membrane
E) thylakoid membrane and plasma membrane
21) In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space,
whereas in chloroplasts, chemiosmosis translocates protons from
A) the stroma to the photosystem II.
B) the matrix to the stroma.
C) the stroma to the thylakoid space.
D) the intermembrane space to the matrix.
E) the thylakoid space to the stroma.
22) 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, whereas respiration releases it.
C) Photosynthesis occurs only in plants and respiration occurs only in animals.
D) ATP molecules are produced in photosynthesis and used up in respiration.
E) Respiration is anabolic and photosynthesis is catabolic.
23) Where are the molecules of the electron transport chain found in plant cells?
A) thylakoid membranes of chloroplasts
B) stroma of chloroplasts
C) outer membrane of mitochondria
D) matrix of mitochondria
E) cytoplasm
24) In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during
A) photosynthesis only.
B) respiration only.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration only.
25) Reduction of oxygen to form water occurs during
A) photosynthesis only.
B) respiration only.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration only.
26) Reduction of NADP+ occurs during
A) photosynthesis.
B) respiration.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration.
27) The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during
A) photosynthesis.
B) respiration.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration.
28) Generation of proton gradients across membranes occurs during
A) photosynthesis.
B) respiration.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration.
29) 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 inversely related.
C) They are logarithmically related.
D) They are separate phenomena.
E) They are only related in certain parts of the spectrum.
30) P680+ is said to be the strongest biological oxidizing agent. Why?
A) It is the receptor for the most excited electron in either photosystem.
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) This molecule has a stronger attraction for electrons than oxygen, to obtain electrons from water.
E) It has a positive charge.
31) 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 was selected against in some species.
B) Photosynthesis with only photosystem I is more ancestral.
C) Photosystem II may have evolved to be more photoprotective.
D) Linear electron flow is more primitive than cyclic flow of electrons.
E) Cyclic flow is more necessary than linear electron flow.
32) Cyclic electron flow may be photoprotective (protective to light-induced damage). Which of the
following experiments could provide information on this phenomenon?
A) 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
B) 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
C) use bacteria that have only cyclic flow and look for their frequency of mutation damage at different
light intensities
D) use bacteria with only cyclic flow and measure the number and types of photosynthetic pigments
they have in their membranes
E) use plants with only photosystem I operative and measure how much damage occurs at different
wavelengths
33) 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.
E) They take up and remove toxins from the groundwater.
34) 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 side facing the thylakoid space.
B) on the ATP molecules themselves.
C) on the pigment molecules of photosystem I and photosystem II.
D) on the stromal side of the membrane.
E) built into the center of the thylakoid stack (granum).
35) 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) donate electrons
B) act as reducing agents
C) act as oxidizing agents
D) transport protons within the mitochondria and chloroplasts
E) both oxidize and reduce during electron transport
36) In a cyanobacterium, the reactions that produce NADPH occur in
A) the light reactions alone.
B) the Calvin cycle alone.
C) both the light reactions and the Calvin cycle.
D) neither the light reactions nor the Calvin cycle.
E) the chloroplast, but is not part of photosynthesis.
37) The reactions that produce molecular oxygen (O2) take place in
A) the light reactions alone.
B) the Calvin cycle alone.
C) both the light reactions and the Calvin cycle.
D) neither the light reactions nor the Calvin cycle.
E) the chloroplast, but are not part of photosynthesis.
38) The accumulation of free oxygen in Earth’s atmosphere began
A) with the origin of life and respiratory metabolism.
B) with the origin of photosynthetic bacteria that had photosystem I.
C) with the origin of cyanobacteria that had both photosystem I and photosystem II.
D) with the origin of chloroplasts in photosynthetic eukaryotic algae.
E) with the origin of land plants.
39) 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 always be higher.
B) The dissolved oxygen in the flask with algae will always be lower.
C) The dissolved oxygen in the flask with algae will be higher in the light, but the same in the dark.
D) The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark.
E) The dissolved oxygen in the flask with algae will not be different from the control flask at any time.
40) Where do the enzymatic reactions of the Calvin cycle take place?
A) stroma of the chloroplast
B) thylakoid membranes
C) matrix of the mitochondria
D) cytosol around the chloroplast
E) thylakoid space
41) What is the primary function of the Calvin cycle?
A) use ATP to release carbon dioxide
B) use NADPH to release carbon dioxide
C) split water and release oxygen
D) transport RuBP out of the chloroplast
E) synthesize simple sugars from carbon dioxide
42) In C3 photosynthesis, the reactions that require ATP take place in
A) the light reactions alone.
B) the Calvin cycle alone.
C) both the light reactions and the Calvin cycle.
D) neither the light reactions nor the Calvin cycle.
E) the chloroplast, but is not part of photosynthesis.
43) In a plant leaf, the reactions that produce NADH occur in
A) the light reactions alone.
B) the Calvin cycle alone.
C) both the light reactions and the Calvin cycle.
D) neither the light reactions nor the Calvin cycle.
E) the chloroplast, but is not part of photosynthesis.
44) The NADPH required for the Calvin cycle comes from
A) reactions initiated in photosystem I.
B) reactions initiated in photosystem II.
C) the citric acid cycle.
D) glycolysis.
E) oxidative phosphorylation.
45) Reactions that require CO2 take place in
A) the light reactions alone.
B) the Calvin cycle alone.
C) both the light reactions and the Calvin cycle.
D) neither the light reactions nor the Calvin cycle.
E) the chloroplast, but is not part of photosynthesis.
46) Which of the following statements best represents the relationships between the light reactions and
the Calvin cycle?
A) The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, i,
and NADP+ to the light reactions.
B) The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the
cycle provides water and electrons to the light reactions.
C) The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle
supplies the light reactions with sugars to produce ATP.
D) The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle
provides the light reactions with water to split.
E) There is no relationship between the light reactions and the Calvin cycle.
47) Three “turns” of the Calvin cycle generate a “surplus” molecule of glyceraldehyde 3-phosphate
(G3P). Which of the following is a consequence of this?
A) Formation of a molecule of glucose would require nine “turns.”
B) G3P more readily forms sucrose and other disaccharides than it does monosaccharides.
C) Some plants would not taste sweet to us.
D) The formation of sucrose and starch in plants involves assembling G3P molecules, with or without
further rearrangements.
E) Plants accumulate and store G3P.
48) 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) inactivation of RuBP carboxylase enzyme
C) regeneration of ATP from ADP
D) regeneration of RuBP
E) regeneration of NADP+