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

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

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

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

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

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

Question 7

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

Answer 7

d

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

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 phototsystem 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

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

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

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

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.
e. none of these

Answer 13

c

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

Question 15

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

Answer 15

b

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

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

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

Question 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 19

d

Question 20

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 20

b

Question 21

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 21

c

Question 22

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

Answer 22

b

Question 23

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 23

c

Question 24

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 24

d

Question 25

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 25

d

Question 26

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 26

b

Question 27

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 27

e

Question 28

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 28

b

Question 29

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 29

c

Question 30

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 30

d

Question 31

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 31

c

Question 32

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 32

e

Question 33

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 33

b

Question 34

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

Answer 34

b

Question 35

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

Answer 35

b

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 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 36

a

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 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 37

a

Question 38

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 38

b

Question 39

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 39

a

Question 40

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

Answer 40

a

Question 41

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

Answer 41

a

Question 42

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 42

d

Question 43

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

Answer 43

b

Question 44

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 44

d

Question 45

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

Answer 45

b

Question 46

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 46

a

Question 47

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 47

a

Question 48

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 48

b

Question 49

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 49

d

Question 50

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 50

a

Question 51

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

Answer 51

a

Question 52

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 52

b

Question 53

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 53

c

Question 54

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 54

d

Question 55

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 55

d

Question 56

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 56

b

Question 57

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 57

d

Question 58

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

Answer 58

c

Question 59

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 59

a

Question 60

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

Answer 60

b

Question 61

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 61

b

Question 62

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 62

e

Question 63

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

Answer 63

a

Question 64

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 64

a

Question 65

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 65

b

Question 66

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

Answer 66

d

Question 67

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 67

a

Question 68

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 68

b

Question 69

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 69

a

Question 70

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 70

a

Question 71

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 71

a

Question 72

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 72

d

Question 73

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 73

a

Question 74

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 74

b

Question 75

Explain the significance of thylakoid disks in the process of photosynthesis.

Answer 75

Thylakoid disks are contained within chloroplasts and function as sites for a light-trapping reaction. They are formed by the folding of a third membrane within the chloroplast. The folding of the thylakoid membrane creates two spaces in the chloroplast in addition to the intermembrane space. The stroma lies within the inner membrane and outside the thylakoid membrane. In addition to the stroma, there is a thylakoid space within the thylakoid disks. The trapping of light and the production of oxygen take place in the thylakoid disks. The dark reactions, in which CO2 is fixed to carbohydrates, take place in the stroma.

Question 76

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 76

b

Question 77

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 77

b

Question 78

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 78

c

Question 79

_____ 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 79

d