Photosynthesis

Question 1

The region of the chloroplast between the inner membrane and the thylakoid membrane is called
a. the stroma.
b. the thylakoid space.
c. the intermembrane
space.
d. the grana

Answer 1

a. stroma

Question 2

In chloroplasts,
a. the light reactions take place in the thylakoid disks, whereas the dark reactions occur in the stroma

b. the dark reactions take place in the thylakoid disks, whereas the light reactions occur in the stroma

c. the light reactions take place in the thylakoid space, whereas the dark reactions occur in the stroma

d. the dark reactions take place in the thylakoid space, whereas the light reactions occur in the stroma

e. none of these

Answer 2

a. the light reactions take place in the thylakoid disks, whereas the dark reactions occur in the stroma

Question 3

In which part of the chloroplast does production of oxygen during photosynthesis primarily
occur?
a. Grana.
b. Thylakoid disks.
c. Stroma
d. Thylakoid space.
e. It is not known where this reaction occurs in the chloroplast.

Answer 3

b. Thylakoid disks.

Question 4

In which part of the chloroplast does reduction of CO2 during photosynthesis primarily occur?
a. Grana.
b. Thylakoid disks.
c. Stroma.
d. Thylakoid space.
e. It is not known where this reaction occurs in the
chloroplast.

Answer 4

c. Stroma.

Question 5

Accessory pigments
a. transfer electrons to reaction center chlorophylls.
b. transfer energy to reaction center chlorophylls.
c. transfer electrons from reaction center chlorophylls to
phaeophytins.
d. transfer electrons from reaction center chlorophylls to ferredoxin.
e. All of these statements are true.

Answer 5

b. transfer energy to reaction center chlorophylls

Question 6

Photosynthetic bacteria which do not use water as the ultimate source of electrons
a. only contain chlorophyll a.
b. only contain chlorophyll b.
c. do not produce oxygen.
d. have two photosystems.
e. none of these

Answer 6

c. do not produce oxygen.

Question 7

The key element at the center of chlorophyll is
a. chlorine.
b. copper.
c. iron.
d. magnesium
e. manganese.

Answer 7

d. magnesium

Question 8

Cyanobacteria contain
a. only chlorophyll a.
b. only chlorophyll b.
c. both chlorophyll a and chlorophyll b.
d. bacteriochlorophyll.
e. no chlorophyll at all

Answer 8

a. only chlorophyll a.

Question 9

Two different types of chlorophyll are used by most plants for the following reason:
a. Two chlorophylls allow for absorbing light from a larger portion of the light spectrum.
b. The different chorophylls are used in different parts of the photosynthesis process.
c. One type is used in photosystem I and the other in photosystem II.
d. The different chlorophylls are located in different compartments of the chloroplast.
e. It is not know why there are two different chlorophylls.

Answer 9

a. Two chlorophylls allow for absorbing light from a larger portion of the light spectrum.

Question 10

Wavelengths of what color are mostly responsible for the reactions in the light phase of
photosynthesis?
a. Blue.
b. Green.
c. Red
d. Blue and red.
e. All three colors.

Answer 10

d. Blue and red.

Question 11

Green plants contain
a. only chlorophyll a.
b. only chlorophyll b.
c. both chlorophyll a and chlorophyll b.
d. bacteriochlorophyll.
e. chlorophyll a, chlorophyll b, and
bacteriochlorophyll

Answer 11

c. both chlorophyll a and chlorophyll b.

Question 12

Which of the following is true concerning chlorophyll?
a. It abosrbs green light, which is why leaves are green
b. Chlorophyll a and b each have peaks of absorption at two different wavelengths
c. Chlorophyll a has a maximum absorption at 600 nm
d. Between the two chlorophylls, light is absorbed between 400 and 700 nm
e. none of these

Answer 12

b. Chlorophyll a and b each have peaks of absorption at two different wavelengths

Question 13

Chlorophyll differs from heme because it
a. has a cyclohexene ring fused to the tetrapyrrole ring
system.
b. has a 16-carbon unbranched side chain.
c. contains magnesium rather than iron.
d. has a fully saturated tetrapyrrole ring.

Answer 13

c. contains magnesium rather than iron.

Question 14

While chlorophyll contains a different metal ion, its ring structure is very similar to the ring
structure in steroids.
a. True
b. False

Answer 14

b. False

Question 15

Light with short wavelengths has less energy than light with long wavelengths.
a. True
b. False

Answer 15

b. False

Question 16

A specialized pair of chlorophylls exists at
a. the antenna complexes.
b. the accessory pigments.
c. the reaction centers.
d. the stroma.
e. the bottom of the roots in most
plants

Answer 16

c. the reaction centers.

Question 17

The light reactions drive the redox process that involves the following pairs of
reactants/products
a. H2O/O2 and NADP+/NADPH
b. H2O/O2 and NADH/NAD+
c. O2/H2O and NADPH/NADP+
d. H2O/O2 and FAD/FADH2

Answer 17

a. H2O/O2 and NADP+/NADPH

Question 18

19. The light phase of photosynthesis is closest to which other metabolic process?
    a. Anaerobic Glycolysis.
    b. The Pentose Monophosphate Pathway.
    c. The Kreb’s Cycle.
    d. The Electron Transport System
    e. The reactions in the light phase are not similar to any other pathway.

Answer 18

d. The Electron Transport System

Question 18

Which of the following is not a component of the electron transport chain that links Photosystem I and Photosystem II?
a. NADPH
b. pheophytin
c. plastoquinone
d. cytochrome f

Answer 18

a. NADPH

Question 19

The process of ATP synthesis in chloroplasts is referred to as
a. oxidative phosphorylation.
b. photophosphorylation
c. reductive phosphorylation
d. substrate-level
phosphorylation.
e. none of these

Answer 19

b. photophosphorylation

Question 20

Which of the following statements concerning the light reactions of photosynthesis is false?
a. Photophosphorylation results from the proton gradient across the thylakoid
membrane.
b. Photosystem II is devoted to water oxidation.
c. P700 is Photosystem II.
d. Photosystem I is devoted to NADP+ reduction.

Answer 20

c. P700 is Photosystem II.

Question 21

The transfer of electrons from water to NADP+ to produce oxygen and NADPH is a highly exergonic process.
a. True
b. False

Answer 21

b. False

Question 22

The terminal electron acceptor during the light phase of photosynthesis in green plants is
a. Hydrogen (H2 → H2O).
b. NAD+ ( → NADH).
c. NADP+ ( → NADPH).
d. Oxygen (O2 → H2O).
e. Sulfur ( → H2S).

Answer 22

c. NADP+ ( → NADPH).

Question 23

Which of the following statements concerning the light reactions of photosynthesis is false?
a. There are two photosystems linked by an electron transport chain
b. Electron transport is coupled to production of ATP
c. The production of NADPH is carried out by Photosystem I, whereas the splitting of
water is carried out by Photosystem II
d. Carbon dioxide fixation takes place

Answer 23

d. Carbon dioxide fixation takes place

Question 24

Light energy absorbed in chloroplasts is used in the light phase for all of these reactions, except: a. To reduce water. b. To make ATP. c. To generate NADPH. d. To reduce water and to generate oxygen, O2. e. All of these occur during the light phase.

Answer 24

d. To reduce water and to generate oxygen, O2.

Question 25

The oxygen evolving complex consists of a. accessory pigments. b. a manganese-containing protein. c. the reaction center chlorophylls. d. ferredoxin. e. none of these

Answer 25

b. a manganese-containing protein.

Question 26

The electrons used in photosynthesis come first from this molecule or atom: a. Hydrogen (H2). b. Manganese atom (Mn). c. NADPH d. Oxygen (O2). e. Water (H2O).

Answer 26

e. Water (H2O).

Question 27

The reactions during the light phase of photosynthesis include the following: 1. Light absorption in photosystem I 2. Light absorption in photosystem II 3. Formation of O2 from water 4. Formation of NADPH 5. Formation of ATP The order of the reactions is as follows: a. 4 → 2 → 3 → 1 → 5. b. 3 → 2 → 5 → 1 → 4. c. 3 → 1 → 5 → 2 → 4. d. 4 → 1 → 5 → 2 → 3. e. 5 → 2 → 4 → 1 → 3.

Answer 27

b. 3 → 2 → 5 → 1 → 4.

Question 28

Which of the following correctly describes a major difference between pheophytins and chlorophylls? a. Pheophytins contain iron in their centers while chlorophylls contain magnesium. b. Chlorophylls contain iron in their centers while pheophytins contain magnesium. c. Pheophytins contain no metal ion in their centers. d. Pheophytins aren't at all like chlorophylls, but are quinones. e. none of these

Answer 28

c. Pheophytins contain no metal ion in their centers.

Question 29

Which of the following statements concerning the photosynthetic reaction center of Rhodopseudomonas viridis is false? a. There is a pair of chlorophylls in a special environment. b. Accessory pigments play a role in trapping of light. c. A separation of charge represents stored energy. d. The electrons being transferred can take either of two possible paths.

Answer 29

d. The electrons being transferred can take either of two possible paths.

Question 30

Which of the following is true? a. A protein with a manganese ion is key to the conversion of O2 to water b. The electron transport chain in photosynthesis is identical to the one in mitochondria c. Parts of the electron transport chain in photosynthesis are similar to the electron transport chain in mitochondria d. Photosynthesis is the exact opposite of respiration e. none of these

Answer 30

c. Parts of the electron transport chain in photosynthesis are similar to the electron transport chain in mitochondria

Question 31

Which of the following is the mobile electron carrier from Photosystem II to the cytochrome b6f complex? a. cyctochrome c b. pheophytin c. plastocyanin d. ferredoxin e. none of these

Answer 31

e. none of these

Question 32

During cyclic electron transport a. only Photosystem II is involved. b. only Photosystem I is involved. c. both photosystems are involved. d. neither photosystem is involved.

Answer 32

b. only Photosystem I is involved.

Question 33

During Z-scheme photosynthesis, ferredoxin oxidizes NADPH. a. True b. False

Answer 33

b. False

Question 34

Ferredoxin is important in photosynthesis in forming NADH. a. True b. False

Answer 34

b. False

Question 35

It is believed that the ratio of cyclic electron transport to Z-scheme photosynthesis changes in response to metabolic demands. If a plant were actively synthesizing starch from the glucose produced, how would it alter these processes compared to a plant just performing the Calvin cycle to produce glucose? a. More cyclic photophosphorylation, less Z-scheme. b. More Z-scheme photosynthesis, less cyclic photophosphorylation. c. No significant difference. d. Impossible to predict from the information provided.

Answer 35

a. More cyclic photophosphorylation, less Z-scheme.

Question 36

It is believed that the ratio of cyclic electron transport to Z-scheme photosynthesis changes in response to metabolic demands. If a plant were using the C4 Hatch-Slack pathway, how would it alter these processes compared to a plant just performing the standard C3 Calvin cycle to produce glucose? a. More cyclic photophosphorylation, less Z-scheme. b. More Z-scheme photosynthesis, less cyclic photophosphorylation. c. No significant difference. d. Impossible to predict from the information provided.

Answer 36

a. More cyclic photophosphorylation, less Z-scheme.

Question 37

It is believed that the ratio of cyclic electron transport to Z-scheme photosynthesis changes in response to metabolic demands. If a plant were actively engaged in a large amount of reductive biosynthesis, requiring NADPH, how would it alter these processes compared to a plant just performing the Calvin cycle to produce glucose? a. More cyclic photophosphorylation, less Z-scheme. b. More Z-scheme photosynthesis, less cyclic photophosphorylation. c. No significant difference. d. Impossible to predict from the information provided.

Answer 37

b. More Z-scheme photosynthesis, less cyclic

Question 38

While actively engaging in photosynthesis under illumination, a. the pH of the thylakoid space would be lower than that of the stroma. b. the pH of the thylakoid space would be greater than that of the stroma. c. the pH of the thylakoid space and of the stroma would be about the same. d. it would be impossible to predict the relative pH's of the thylakoid space and of the stroma.

Answer 38

a. the pH of the thylakoid space would be lower than that of the stroma.

Question 39

40. The synthesis of ATP in chloroplasts uses a proton gradient similar to the one used in mitochondria. a. True b. False

Answer 39

a. True

Question 40

The ATP synthase in photosynthesis is similar in structure and function to its mitochondrial counterpart. a. True b. False

Answer 40

a. True

Question 41

The production of ATP in photosynthesis a. is not linked to a proton gradient across a membrane b. does not involve membrane-bound proteins c. does not require the presence of light d. provides the energy for production of sugars e. occurs only in the dark

Answer 41

d. provides the energy for production of sugars

Question 42

43. Anaerobic, photosynthetic bacteria differ from green plants in that they only have one type of chlorophyll. a. True b. False

Answer 42

b. False

Question 43

Bacterial products of photosynthesis, other than oxygen and sugars, can include all of these, except: a. H2S b. NH3 c. CH4 d. Water e. All of these are products of photosynthetic bacteria.

Answer 43

d. Water

Question 44

The earliest photosynthetic organisms most likely used water as an electron source. a. True b. False

Answer 44

b. False

Question 45

After the reaction with Rubisco, the major difference between the Calvin Cycle and gluconeogenesis in liver is the following reaction: a. The reduction of 1,3 bisphosphoglyceric acid uses NADPH instead of NADH b. The formation of 1,3 bisphosphoglyceric acid from 3-phosphoglyceric acid uses GTP instead of ATP. c. Phosphatases are not required in plants. d. The reduction of 1,3 bisphosphoglyceric acid uses NADH instead of NADPH e. More than one of these reactions is substantially different in plants compared to liver.

Answer 45

a. The reduction of 1,3 bisphosphoglyceric acid uses NADPH instead of NADH

Question 46

Where does the actual CO2 fixation process takes place? a. the stroma. b. the thylakoid space. c. the intermembrane space. d. the cytosol. e. none of these

Answer 46

a. the stroma.

Question 47

The dark phase of photosynthesis is closest to this other metabolic process: a. Anaerobic Glycolysis. b. The Pentose Phosphate Pathway. c. The Kreb's Cycle. d. The Electron Transport System e. The reactions in the dark phase are not similar to any other pathway.

Answer 47

b. The Pentose Phosphate Pathway

Question 48

The actual CO2 fixation process in photosynthesis is the addition of CO2 into a 5 carbon compound to yield a. ribulose 5-phosphate. b. ribulose 1,5-bisphosphate. c. erythrose 4-phosphate. d. 3-phosphoglycerate. e. glucose 6-phosphate

Answer 48

d. 3-phosphoglycerate.

Question 49

The enzyme ribulose 1,5-bisphosphate carboxylase a. consists of eight catalytic subunits encoded by a chloroplast and eight regulatory subunits encoded by a nuclear gene. b. is difficult to isolate and study because it occurs in small amount in plant cells. c. is nonallosteric. d. is not involved in reactions linked to oxygen.

Answer 49

a. consists of eight catalytic subunits encoded by a chloroplast and eight regulatory subunits encoded by a nuclear gene.

Question 50

The Calvin Cycle for CO2 fixation uses most of the same reactions as the pentose phosphate pathway. a. True b. False

Answer 50

a. True

Question 51

In the first reaction of carbon dioxide fixation in photosynthesis, CO2 reacts with a. ribulose 5-phosphate. b. ribulose 1,5-bisphosphate. c. ribose 5-phosphate. d. xylulose 5-phosphate. e. glyceraldehyde 3-phosphate

Answer 51

b. ribulose 1,5-bisphosphate.

Question 52

After the CO2 fixation step in photosynthesis, the production of sugars takes place a. as a reversal of glycolysis. b. as a reversal of the citric acid cycle. c. in the same manner as gluconeogenesis. d. as a reversal of the pentose phosphate pathway. e. the same as in glycolysis

Answer 52

c. in the same manner as gluconeogenesis.

Question 53

For the net synthesis of one six-carbon sugar from CO2 in photosynthesis there is a requirement for a. 12 ATP and 12 NADPH. b. 18 ATP and 18 NADPH. c. 12 ATP and 18 NADPH. d. 18 ATP and 12 NADPH.

Answer 53

d. 18 ATP and 12 NADPH

Question 54

The fixation of CO2 to form sugars requires the following: a. Oxygen, O2. b. ATP. c. NADPH. d. Both ATP and NADPH. e. All 3 of these are required to convert CO2 to sugar.

Answer 54

d. Both ATP and NADPH.

Question 55

In the Calvin cycle a reshuffling of intermediates is necessary a. to ensure uniform incorporation of CO2 into newly synthesized sugars b. to regenerate the key intermediate with which CO2 initially reacts c. to use as little ATP as possible d. to use as little NADPH as possible

Answer 55

b. to regenerate the key intermediate with which CO2 initially reacts

Question 56

Which of these statements concerning the Calvin Cycle is false? a. There is significant overlap between these reactions and glycolysis. b. During the process, ATP is used with an ADP product. c. Fructose 1,6 bisphosphate is an intermediate in this pathway. d. NADP+ is converted to NADPH during this pathway. e. At least one reduction reaction occurs during this pathway.

Answer 56

d. NADP+ is converted to NADPH during this pathway

Question 57

The efficiency of energy use in photosynthesis is approximately a. 99% b. 65% c. 30% d. 2%

Answer 57

c. 30%

Question 58

The stoichiometric balance of the Calvin Cycle has 6 ribulose 1,5 bisphosphate and 6 CO2 forming twelve 3-phosphoglycerate. Of these 12 molecules, two are used to make glucose and the other ten are used to regenerate the ribulose 1,5 bisphosphate. a. True b. False

Answer 58

a. True

Question 59

The nuclear gene for Rubisco codes for the catalytic subunit, while the regulatory gene is found in the chloroplast. a. True b. False

Answer 59

b. False

Question 60

After the formation of 3-phosphoglyceric acid, the reactions in the dark phase of photosynthesis are essentially the same as those in gluconeogenesis. a. True b. False

Answer 60

b. False

Question 61

The enzyme, ribulose 1,5 bisphosphate carboxylase (Rubisco), is: a. one of the most abundant proteins in nature. b. about 15% of the protein content of the chloroplast c. a multisubunit enzyme d. consistent with the endosymbiotic origin for organelles such as chloroplasts and mitochondria e. all of these

Answer 61

e. all of these

Question 62

Rubisco is a rare example of an enzyme whose genetic information is found in two different cellular compartments. a. True b. False

Answer 62

a. True

Question 63

In order to regenerate ribulose 1,5 bisphosphate, the following reaction is required: a. A phosphate group must be added to ribulose-1-phosphate. b. The enzyme involved is phosphoribulose kinase. c. ATP is used as a source of phosphate. d. Both phosphoribulose kinase and ATP are needed. e. All of these statements are true.

Answer 63

a. A phosphate group must be added to ribulose-1-phosphate.

Question 64

The essential enzyme for the C4 pathway is a. ribulose bisphosphate carboxylase:oxygenase b. phosphoenolpyruvate carboxylase c. ferredoxin-thioredoxin reductase d. glyoxylate oxygenase e. none of these

Answer 64

b. phosphoenolpyruvate carboxylase

Question 65

Which of the following is NOT an intermediate in the C4 pathway? a. phosphoenolpyruvate b. oxaloacetate c. malate d. fumarate

Answer 65

d. fumarate

Question 66

The C4 pathway for carbon dioxide fixation has what requirement compared to the Calvin cycle? a. requires more ATP b. requires less ATP c. requires more NADPH d. requires less NADPH e. none of these

Answer 66

a. requires more ATP

Question 67

In plants that use the C4 pathway there is less likelihood for the occurrence of which process compared to plants that rely exclusively on the Calvin cycle? a. gluconeogenesis b. photorespiration c. the pentose phosphate pathway d. lipid anabolism

Answer 67

b. photorespiration

Question 68

Of the two photosynthetic pathways, Calvin Cycle or Hatch-Slack Pathway, only the Calvin Cycle uses the pentose phosphate pathway. a. True b. False

Answer 68

a. True

Question 69

One very important reason for the Hatch-Slack Pathway of photosynthesis is to increase the concentration of CO2 in the chloroplast. a. True b. False

Answer 69

a. True

Question 70

The Hatch-Slack Pathway is important in tropical zones since, in order to conserve water, the pores of tropical leaves are very small. a. True b. False

Answer 70

a. True

Question 71

The first CO2 fixing reaction of the Hatch-Slack pathway is: a. Conversion of phosphoenolpyruvate and CO2 to oxaloacetate. b. Conversion of succinate and CO2 to α-ketoglutarate. c. Conversion of acetate and CO2 to pyruvate. d. Conversion of acetate and CO2 to malonate. e. More than one of these reactions can initiate the Hatch-Slack Pathway.

Answer 71

d. Conversion of acetate and CO2 to malonate.

Question 72

Presence of oxygen can poison the reaction of Rubisco, due to an alternate reaction in which the ribulose 1,5 bisphosphate is oxidized, rather than reacting with CO2 a. True b. False

Answer 72

a. True

Question 73

Which of the following is not true regarding the C4 pathway? a. The C4 pathway allows for the concentration of CO2 b. the KM for CO2 is lower with Rubisco than for phosphoenolpyruvate carboxylase c. Rubisco also has an oxygenase activity that appears to be a wasteful process in terms of energy production d. The C4 pathway alleviates some of the wastefulness of the oxygenase activity of Rubisco by concentrating CO2 in the interior of the plant.

Answer 73

b. the KM for CO2 is lower with Rubisco than for phosphoenolpyruvate carboxylase

Question 74

Which of the following types of bacteria contain bacteriochlorophylls, but do not use water as the ultimate source of electrons for the redox reactions of photosynthesis and do not produce oxygen? a. Acidobacteria and cyanobacteria b. Green and purple sulfur bacteria c. Chlamydiae and fusobacteria d. Spirochaetes and actinobacteria

Answer 74

b. Green and purple sulfur bacteria

Question 75

Which of the following types of chlorophyll increases the portion of the visible spectrum that is absorbed and thus enhances the efficiency of photosynthesis in green plants compared with cyanobacteria? a. Chlorophyll a b. Chlorophyll b c. Chlorophyll c d. Chlorophyll d

Answer 75

b. Chlorophyll b

Question 76

Which of the following is a similarity between light reaction and dark reaction? a. Both reactions fix CO2. b. Both reactions split water into hydrogen and oxygen. c. Both reactions carry out redox reactions. d. Both reactions involve the Calvin cycle.

Answer 76

c. Both reactions carry out redox reactions.

Question 77

____ is a photosynthetic pigment that differs from chlorophyll only in having two hydrogens atoms in place of one magnesium atom. a. Phycobiliprotein b. Bacteriorhodopsin c. Xanthophyll d. Pheophytin

Answer 77

d. Pheophytin