Deck 22: Photosynthesis

Question 1

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 1

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

Question 2

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 2

The Electron Transport System

Question 3

The key element at the center of chlorophyll is

A) chlorine.
B) copper.
C) iron.
D) magnesium.
E) manganese.

Answer 3

magnesium.

Question 4

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.

Question 5

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

Question 6

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.

Question 7

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

Question 8

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

Question 9

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

Question 10

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

Question 11

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

Question 12

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

Question 13

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.

Question 14

Cyanobacteria contain

A) only chlorophyll a.
B) only chlorophyll b.
C) both chlorophyll a and chlorophyll b.
D) bacteriochlorophyll.
E) no chlorophyll at all

Question 15

Light with short wavelengths has less energy than light with long wavelengths.

Question 16

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

Question 17

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

Question 18

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.

Question 19

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

Question 20

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.

Question 21

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.

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).

Question 23

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

Question 24

Ferredoxin is important in photosynthesis in forming NADH.

Question 25

Which of the following is the mobile electron carrier from Photosystem II to the cytochrome b₆ f complex?

A) cyctochrome c
B) pheophytin
C) plastocyanin
D) ferredoxin
E) none of these

Question 26

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.

Question 27

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

Question 28

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

Question 29

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

Question 30

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

Question 31

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).

Question 32

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.

Question 33

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

Question 34

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.

Question 35

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.

Question 36

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.

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.

Question 38

During Z-scheme photosynthesis, ferredoxin oxidizes NADPH.

Question 39

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.

Question 40

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.

Question 41

In the first reaction of carbon dioxide fixation in photosynthesis, CO₂ reacts with

A) ribulose 5-phosphate.
B) ribulose 1,5- bis phosphate.
C) ribose 5-phosphate.
D) xylulose 5-phosphate.
E) glyceraldehyde 3-phosphate

Question 42

The enzyme ribulose 1,5- bis phosphate 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.

Question 43

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

Question 44

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

Question 45

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.

Question 46

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

Question 47

The earliest photosynthetic organisms most likely used water as an electron source.

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- bis phosphate.
C) erythrose 4-phosphate.
D) 3-phosphoglycerate.
E) glucose 6-phosphate

Question 49

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 bis phosphoglyceric acid uses NADPH instead of NADH
B) The formation of 1,3 bis phosphoglyceric acid from 3-phosphoglyceric acid uses GTP instead of ATP.
C) Phosphatases are not required in plants.
D) The reduction of 1,3 bis phosphoglyceric acid uses NADH instead of NADPH
E) More than one of these reactions is substantially different in plants compared to liver.

Question 50

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 bis phosphate 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.

Question 51

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.

Question 52

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.

Question 53

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

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.

Question 55

The ATP synthase in photosynthesis is similar in structure and function to its mitochondrial counterpart.

Question 56

The stoichiometric balance of the Calvin Cycle has 6 ribulose 1,5 bis phosphate 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 bis phosphate.

Question 57

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

Question 58

The efficiency of energy use in photosynthesis is approximately

A) 99%
B) 65%
C) 30%
D) 2%

Question 59

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

Question 60

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

Question 61

​ 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.

Question 62

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

Question 63

Presence of oxygen can poison the reaction of Rubisco, due to an alternate reaction in which the ribulose 1,5 bis phosphate is oxidized, rather than reacting with CO₂

Question 64

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

Question 65

​ _____ 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

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

Question 67

The essential enzyme for the C₄ pathway is

A) ribulose bis phosphate carboxylase:oxygenase
B) phosphoenolpyruvate carboxylase
C) ferredoxin-thioredoxin reductase
D) glyoxylate oxygenase
E) none of these

Question 68

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.

Question 69

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

Question 70

​ 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

Question 71

​ 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

Question 72

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

Question 73

In order to regenerate ribulose 1,5 bis phosphate, 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.

Question 74

The enzyme, ribulose 1,5 bis phosphate 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

Question 75

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

Question 76

Which of the following is not true regarding the C₄ pathway?

A) The C₄ pathway allows for the concentration of CO₂
B) the K_M 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.

Question 77

Which of the following is NOT an intermediate in the C₄ pathway?

A) phosphoenolpyruvate
B) oxaloacetate
C) malate
D) fumarate

Question 78

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

Question 79

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