Chapter 10- Photosynthesis

Question 1

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.

Answer 1

O2

Question 2

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

Answer 2

ATP and NADPH

Question 3

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.

Answer 3

Fossil Fuels

Question 4

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

Answer 4

Stroma of the chloroplast

Question 5

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

Answer 5

Autotrophs

Question 6

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

Answer 6

In the cytosol

Question 7

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.

Answer 7

splitting water molecules

Question 8

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?

Answer 8

Blue and violet

Question 9

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?

Answer 9

Blue and red

Question 10

10) In the thylakoid membranes, what is the main role of the antenna pigment molecules?

Answer 10

harvest photons and transfer light energy to the reaction-center chlorophyll

Question 11

11) Which of the events listed below occurs in the light reactions of photosynthesis?

Answer 11

Light is absorbed and funneled to reaction-center chlorophyll a.

Question 12

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.

Answer 12

D) The electron vacancies in P680+ are filled by electrons derived from water.

Question 13

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

Answer 13

B) receiving electrons from the thylakoid membrane electron transport chain

Question 14

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.

Answer 14

B) to test for liberation of O2 in the light.

Question 15

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

Answer 15

C) ATP and NADPH

Question 16

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

Answer 16

C) cyclic electron flow

Question 17

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+

Answer 17

D) the synthesis of ATP

Question 18

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

Answer 18

A) establishment of a proton gradient across the thylakoid membrane

Question 19

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.

Answer 19

The isolated chloroplasts will make ATP.

Question 20

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

Answer 20

thylakoid membrane and inner mitochondrial membrane

Question 21

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.

Answer 21

the stroma to the thylakoid space.

Question 22

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.

Answer 22

B) Photosynthesis stores energy in complex organic molecules, whereas respiration releases it.

Question 23

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

Answer 23

A) thylakoid membranes of chloroplasts

Question 24

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.

Answer 24

C) both photosynthesis and respiration.

Question 25

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.

Answer 25

B) respiration only.

Question 26

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

Answer 26

A) photosynthesis.

Question 27

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.

Answer 27

D) neither photosynthesis nor respiration.

Question 28

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.

Answer 28

C) both photosynthesis and respiration.

Question 29

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.

Answer 29

B) They are inversely related.

Question 30

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.

Answer 30

D) This molecule has a stronger attraction for electrons than oxygen, to obtain electrons from water

Question 31

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.

Answer 31

B) Photosynthesis with only photosystem I is more ancestral.

Question 32

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

Answer 32

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

Question 33

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.

Answer 33

B) They protect against oxidative damage from excessive light energy.

Question 34

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).

Answer 34

D) on the stromal side of the membrane.

Question 35

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

Answer 35

E) both oxidize and reduce during electron transport

Question 36

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.

Answer 36

A) the light reactions alone.

Question 37

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.

Answer 37

A) the light reactions alone.

Question 38

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.

Answer 38

C) with the origin of cyanobacteria that had both photosystem I and photosystem II

Question 39

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.

Answer 39

D) The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark.

Question 40

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

Answer 40

A) stroma of the chloroplast

Question 41

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

Answer 41

E) synthesize simple sugars from carbon dioxide

Question 42

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.

Answer 42

B) the Calvin cycle alone.

Question 43

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

Answer 43

D) neither the light reactions nor the Calvin cycle.

Question 44

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.

Answer 44

A) reactions initiated in photosystem I.

Question 45

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.

Answer 45

B) the Calvin cycle alone.

Question 46

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.

Answer 46

A) The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, i, and NADP+ to the light reactions.

Question 47

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.

Answer 47

D) The formation of sucrose and starch in plants involves assembling G3P molecules, with or without further rearrangements.

Question 48

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+

Answer 48

D) regeneration of RuBP

Question 49

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

Answer 49

A) The pH within the thylakoid is less than that of the stroma.

Question 50

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

Answer 50

D) all known photoautotrophs, both bacterial and eukaryotic.

Question 51

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

Answer 51

B) O2.

Question 52

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

Answer 52

A) C4 plant.

Question 53

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 are adapted to cold, wet climates.
D) They conserve water more efficiently.
E) They exclude oxygen from their tissues.

Answer 53

B) They use PEP carboxylase to initially fix CO2.

Question 54

54) CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they
A) fix CO2 into organic acids during the night.
B) fix CO2 into sugars in the bundle-sheath cells.
C) fix CO2 into pyruvate in the mesophyll cells.
D) use the enzyme phosphofructokinase, which outcompetes rubisco for CO2.
E) use photosystem I and photosystem II at night.

Answer 54

A) fix CO2 into organic acids during the night.

Question 55

55) Photorespiration lowers the efficiency of photosynthesis by
A) carbon dioxide molecules.
B) 3-phosphoglycerate molecules.
C) ATP molecules.
D) ribulose bisphosphate molecules.
E) RuBP carboxylase molecules.

Answer 55

B) 3-phosphoglycerate molecules.

Question 56

56) 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.
E) C4 plants allow less water loss but CAM plants allow more water loss.

Answer 56

C) Both minimize photorespiration but expend more ATP during carbon fixation.

Question 57

57) If plant gene alterations cause the 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) Less ATP would be generated.
D) There would be more light-induced damage to the cells.
E) Less oxygen would be produced.

Answer 57

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

Question 58

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

Answer 58

A) can continue to fix CO2 even at relatively low CO2 concentrations and high oxygen concentrations.

Question 59

59) If atmospheric CO2 concentrations increase twofold or more, how will plants be affected, disregarding any changes in climate?
A) All plants will experience increased rates of photosynthesis.
B) C3 plants will have faster growth; C4 plants will be minimally affected.
C) C4 plants will have faster growth; C3 plants will be minimally affected.
D) C3 plants will have faster growth; C4 plants will have slower growth.
E) Plant growth will not be affected because atmospheric CO2 concentrations are never limiting for plant growth.

Answer 59

B) C3 plants will have faster growth; C4 plants will be minimally affected.

Question 60

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

Answer 60

C) both in light and dark.