Deck 7: Photosynthesis

Question 1

What are the reactants and products that link the light-dependent and the light-independent reactions of photosynthesis?

A)CO₂ and NADPH
B)ATP and NADH
C)ATP and NADPH
D)FADH₂ and CO₂

Answer 1

C

Question 2

Which of the following are used to generate biofuels?

A)single-celled algae
B)crop plants
C)multicellular algae
D)any plants

Answer 2

A

Question 3

What is the reason why we call "fossil fuels" as such?

A)They are the remnants of fuels.
B)They are the remnants of fossils.
C)They are the remnants of ancient forests.
D)They are the remnants of modern forests.

Answer 3

C

Question 4

What is the primary difference between NAD⁺ and NADP⁺?

A)Both function as electron carriers, but NADP⁺ has a third phosphate group and NAD⁺ does not.
B)NAD⁺ functions as an electron transporter, whereas NADP⁺ does not.
C)Both transport electrons to the electron transport chain (ETC) found on the inner mitochondrial membrane, but NADP⁺ transfers its electrons to the ETC at a higher energy level.
D)NAD⁺ functions as an electron transporter in chloroplasts while NADP⁺ functions as an electron transporter in mitochondria.

Question 5

What is the primary purpose of the light-dependent reactions?

A)to transfer electrons to the primary electron acceptors
B)to provide electrons and energy for the light-independent reactions
C)to generate O₂
D)to create a proton gradient across the thylakoid membrane

Question 6

Which of the following is light absorbed by in photosynthesis?

A)green pigments called chlorophylls and blue pigments called carotenoids
B)green pigments called carotenoids and yellow-orange pigments called chlorophylls
C)green pigments called chlorophylls and red-orange pigments called carotenoids
D)green pigments called chlorophylls and yellow-orange pigments called carotenoids

Question 7

Suppose you explored a new planet and found a photosynthetic organism unlike any on Earth. Also suppose that you repeat Engelmann's classic experiment using this new organism in place of Spirogyra and find that oxygen-dependent bacteria cluster near the green and yellow portions of the spectrum. Which statement summarizes what you have learned?

A)This organism is green, just like plants on Earth.
B)This organism utilizes the most energy-rich photons of the spectrum.
C)The Sun of this new planet emits different wavelengths of light than those emitted by Earth's Sun.
D)This new organism is using yellow and green light to drive photosynthesis.

Question 8

Which sentence best describes fluorescence?

A)A pigment molecule accepts a high-energy electron and releases a photon of energy.
B)A high-energy electron leaves its nucleus and moves to a different molecule.
C)A high-energy electron returns to its ground state by releasing energy in a photon.
D)A low-energy electron moves to a high-energy state by absorbing heat.

Question 9

Which of the following is the traditional source of most oils?

A)single-celled algae
B)crop plants
C)multicellular algae
D)any plants

Question 10

Which of the following best describes what a spectrophotometer is used for?

A)to precisely determine the wavelengths of light reflected by a pigment
B)to precisely determine the rate of light absorbed by a pigment
C)to approximately determine the wavelengths of light absorbed by a pigment
D)to precisely determine the wavelengths of light absorbed by a pigment

Question 11

In Engelmann's classic experiment, why were the oxygen-requiring bacteria clustered around the regions of Spirogyra algae that were bathed in red, blue, and violet light?

A)because photosynthesis is most active in those wavelengths of light and thus more oxygen is consumed by the algae in those regions
B)because chlorophyll is green and thus reflects green light
C)because photosynthesis is most active in those wavelengths of light and thus more oxygen is produced by the algae in those regions
D)because the bacteria were immobile and that is where Engelmann happened to place them

Question 12

Where does photosynthesis occur in eukaryotes?

A)in the mitochondria
B)in the chloroplasts
C)in the plasma membrane
D)in the cytosol

Question 13

Iron is required for primary production. Which of the following is correct to predict?

A)Iron fertilization of oceans can raise N₂ in the atmosphere.
B)Iron fertilization of oceans can lower O₂ in the atmosphere.
C)Iron fertilization of oceans can raise CO₂ in the atmosphere.
D)Iron fertilization of oceans can lower CO₂ in the atmosphere.

Question 14

Which of the following best describes the difference between autotrophs and photoautotrophs?

A)Autotrophs produce their own food, and photoautotrophs use the energy from light to covert CO₂ into an organic form.
B)Autotrophs do not produce their own food, and photoautotrophs do.
C)Autotrophs produce their own food, and photoautotrophs do not.
D)Autotrophs produce their own food, and photoautotrophs use the energy from chemicals to covert CO₂ into an organic form.

Question 15

Where does the Calvin cycle occur?

A)in the thylakoid membrane
B)in the cytosol
C)in the stromal lamellae
D)in the stroma

Question 16

Which of the following organisms can perform photosynthesis?

A)Eukarya only
B)Archaea, Bacteria, and Eukarya
C)Archaea and Eukarya
D)Bacteria and Eukarya

Question 17

Consider the chemical reaction for photosynthesis as a redox reaction. Which of the following is reduced/oxidized?

A)Carbon dioxide is reduced to glucose and water is oxidized to oxygen.
B)Carbon dioxide is oxidized to glucose and water is reduced to oxygen.
C)Carbon dioxide is reduced to oxygen and water is oxidized to glucose.
D)Carbon dioxide is oxidized to oxygen and water is reduced to glucose.

Question 18

Which of the following describes the role of the photosynthetic pigments?

A)to absorb photons of light and transfer the energy to neighbouring molecules
B)to absorb energy and transfer photons of light to neighbouring molecules
C)to absorb photons of light and energy
D)to transfer photons of light and the energy to neighbouring molecules

Question 19

Which of the following is required for photons to be used as a source of energy?

A)They must be particles.
B)They must be energized.
C)They must be absorbed by a molecule.
D)They must be reflected by a molecule.

Question 20

Which of the following are the most abundant of the chlorophylls?

A)chlorophyll a and b
B)chlorophyll a and c
C)chlorophyll b and c
D)chlorophyll a, b, and c

Question 21

Where in a plant cell is ATP synthase found?

A)in the thylakoid and inner mitochondrial membranes
B)in the thylakoid membrane and embedded in the plasma membrane
C)embedded in the plasma membrane and in the inner mitochondrial membranes
D)in the inner mitochondrial membranes only

Question 22

Which complex organic molecule is a major product of the Calvin cycle?

A)ATP
B)CO₂
C)rubisco
D)G3P

Question 23

What is the purpose of the Calvin cycle?

A)to recover electrons lost when water was split
B)to counteract increasing atmospheric CO₂ concentrations (global warming)
C)to capture photons of light
D)to produce sugars using CO₂ as a carbon source

Question 24

Which thylakoid membrane component oxidizes when photosystem I absorbs light energy?

A)NADP⁺ reductase
B)P700
C)plastocyanin
D)P680

Question 25

What is the product of the addition of O₂ to RuBP by rubisco?

A)one molecule of G3P
B)one molecule of 3PGA and one molecule of phosphoglycolate
C)two molecules of phosphoglycolate
D)three molecules of 3PGA

Question 26

Which Calvin cycle products are used in the light reactions?

A)G3P, ATP, and NADPH
B)electrons from CO₂
C)ADP, P_i, and NADP⁺
D)O₂, water, and ATP

Question 27

The Calvin cycle consumes CO₂ and produces which of the following products?

A)ATP
B)G3P
C)NADPH
D)rubisco

Question 28

Suppose that you extract all of the proteins of a leaf and measure the percentage that is rubisco. What percentage of the leaf proteins will the rubisco comprise?

A)10%
B)25%
C)50%
D)75%

Question 29

Where do the electrons from NADPH go in the Calvin cycle?

A)They are added to oxygen, just like in cellular respiration.
B)They are used to regenerate RuBP from G3P.
C)They are transferred to rubisco.
D)They are added to 1, 3-bisphosphoglycerate.

Question 30

Suppose that photosynthetic eukaryotic cells are provided with CO₂ synthesized with heavy oxygen (¹⁸O). Then suppose that the ¹⁸O label will be found in all but one compound. What is that compound?

A)glucose
B)O₂ gas
C)cellulose
D)3-phosphoglycerate

Question 31

If chloroplasts are put in the dark, what must they be provided with in order to continue making sugar?

A)CO₂ and ATP
B)NADPH and ATP
C)NADPH, ATP, and CO₂
D)NADPH, CO₂, and ADP

Question 32

Which of the following best describes the antenna complex?

A)energy-harvesting complex
B)light-harvesting complex
C)sound-harvesting complex
D)colour-harvesting complex

Question 33

Which of the following absorb the photons of light in photosynthesis?

A)chlorophyll and carotenoids
B)chlorophyll and the thylakoid membrane
C)carotenoids and the stroma
D)the thylakoid membrane and the stroma

Question 34

Which products of the light reactions are used in the Calvin cycle?

A)ATP and NADPH
B)CO₂ and RuBP
C)water, O₂, ATP
D)electrons and photons

Question 35

Why is the molecule of chlorophyll a in photosystem I's reaction centre known as P700?

A)because 700 molecules of NADPH are generated per photon of light absorbed
B)because it absorbs 700 photons per minute
C)because exactly 700 accessory pigments are in the photosystem
D)because it absorbs photons with a wavelength of 700 nm

Question 36

What is the reaction centre of a photosystem composed of?

A)a primary electron acceptor, a large number of proteins, and many chlorophyll a molecules
B)a primary electron acceptor, a small number of proteins, and many chlorophyll molecules
C)a primary electron acceptor, a large number of proteins, and special chlorophyll a molecule
D)a primary electron acceptor, a small number of proteins, and special chlorophyll a molecule

Question 37

Why is the molecule of chlorophyll a in photosystem II's reaction centre known as P680?

A)because it absorbs 680 photons per minute
B)because it will generate 680 molecules of ATP per photon absorbed
C)because it absorbs photons with a wavelength of 680 nm
D)because exactly 680 accessory pigments are in the photosystem

Question 38

To which thylakoid membrane does photosystem II donate the electrons it acquires from water?

A)photosystem I
B)plastoquinone
C)cytochrome complex
D)cytochrome c

Question 39

Why do the light reactions have both cyclic and noncyclic electron pathways?

A)to ensure that ATP and NAPDH are generated in a 1:1 molar ratio
B)because only the combination of pathways can generate sufficient NADPH for the light-independent reactions
C)to provide more electrons from water than would be released by the noncyclic pathway
D)because the light-independent reactions require ATP and NADPH in different amounts than are generated by noncyclic electron flow

Question 40

Which thylakoid membrane component does photosystem I draw its electrons from?

A)NADP⁺ reducatase
B)plastocyanin
C)photosystem II
D)water

Question 41

Suppose that you are a botanist looking for new species of C4 plants. Where should you focus your search?

A)in Arizona
B)in the Florida Everglades
C)in an equatorial rainforest
D)in Nova Scotia

Question 42

Explain why we say nearly all life on Earth ultimately depends on the Sun for energy.

Question 43

Why is photorespiration more likely to occur in warm weather?

A)Plants require warm weather (at least 23ºC) to drive photosynthesis.
B)Plants are more likely to close their stomata in the daytime heat than at night when it is cool.
C)Plants are more likely to dehydrate in warm weather, forcing them to close their stomata to conserve water; this prevents CO₂ from entering the leaf.
D)The rubisco enzyme is very temperature-sensitive and becomes less selective in warmer temperatures, allowing it to fix O₂ instead of CO₂.

Question 44

When does a CAM plant take in atmospheric CO₂?

A)from noon to midnight
B)in darkness only
C)in daylight only
D)from midnight to noon

Question 45

What does a CAM plant do with the malate produced by its C4 pathway?

A)distribute it to bundle sheath cells
B)store it in the central vacuole
C)make immediate use of it
D)store it in the stroma

Question 46

At which temperature does photorespiration use as much as 50% of a plant's energy?

A)10ºC
B)20ºC
C)23ºC
D)35ºC

Question 47

The arrangement of photosystems I and II in the thylakoid membrane is exactly like that drawn in the Z-pathway of most textbooks.

Question 48

Which of the following best explains why regulating opening and closing stomata is more difficult in dry and hot environments?

A)Photorespiration becomes a bigger problem as the climate becomes colder.
B)Photorespiration becomes a bigger problem as the climate becomes warmer.
C)Photorespiration becomes a lesser problem as the climate becomes warmer.
D)Photorespiration becomes a lesser problem as the climate becomes colder.

Question 49

Photorespiration is even more detrimental because photoautotrophs cannot use phosphoglycolate.

Question 50

The process of photosynthesis, including all of the enzymes and chemical intermediates, is completely understood.

Question 51

What is the purpose of the C4 pathway?

A)It is more efficient than the Calvin cycle because less ATP is consumed in the process.
B)It replaces the carbon fixation stage of the Calvin cycle.
C)It supplements the activity of rubisco by providing a second source of 3PGA for the reduction stage of the Calvin cycle.
D)It ensures that CO₂ is provided to rubisco and thus prevents photorespiration.

Question 52

When does a C4 plant use rubisco to perform carbon fixation?

A)in daylight only
B)from noon to midnight
C)from midnight to noon
D)in darkness only

Question 53

What are some of the problems that must be addressed when planting C3 plants in hot, arid climates for ornamental purposes?

Question 54

Standard photosynthesis (C3) plants are more susceptible to photorespiration than either C4 or CAM plants. Why do most plants lack the C4 pathway?

A)because rubisco is more efficient in C3 plants when compared to rubisco C4 and CAM plants
B)because C4 and CAM pathways have an energetic cost that makes them advantageous in only very hot and/or arid environments
C)because photorespiration is not a serious problem for most plants
D)because most plant species do not have vacuoles in their cells to store the malate generated from CO₂ taken in during the night

Question 55

Explain why it is important, from a global standpoint, to try to improve the efficiency of photosynthesis in common crops. Specify which aspect(s) of photosynthesis we should target.

Question 56

Compare and contrast the role of O₂ and H₂O in photosynthesis and cellular respiration.

Question 57

Not all plants can use the C4 pathway to avoid photorespiration.

Question 58

Atmospheric O₂ is actually a waste product of photosynthesis.

Question 59

Which molecule associated with photorespiration is toxic to plant cells?

A)phosphoglycolate
B)3PGA
C)glycolate
D)G3P

Question 60

Glucose is the only sugar produced from photosynthesis.

Question 61

For each phrase, choose the most appropriate process.
a.light-dependent reactions only
b.Calvin cycle only
c.light-dependent reactions and the Calvin cycle both
d.neither the light-dependent reactions nor the Calvin cycle
requires G3P to continue

Question 62

Match the name of the process to its description.
a.noncyclic electron flow
b.cyclic electron flow
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of Calvin cycle
e.RuBP regeneration stage of Calvin cycle
This allows for the production of additional ATP to drive the RuBP regeneration process.

Question 63

For each phrase, choose the most appropriate process.
a.light-dependent reactions only
b.Calvin cycle only
c.light-dependent reactions and the Calvin cycle both
d.neither the light-dependent reactions nor the Calvin cycle
creates a proton gradient

Question 64

Match each term with its definition.
a.the generation of ATP via a proton gradient created by light-energized electrons moving down an electron transport chain
b.the site of the light-independent reactions in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid and stromal membranes of chloroplasts
d.membranous connections between granum that allow individual thylakoid lumens to form a single, contiguous compartment
e.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
f.the molecule used to store carbon overnight in CAM plants
g.organisms that use CO₂ as their carbon source and light as their energy source
photoautotrophs

Question 65

Match each term with its definition.
a.the generation of ATP via a proton gradient created by light-energized electrons moving down an electron transport chain
b.the site of the light-independent reactions in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid and stromal membranes of chloroplasts
d.membranous connections between granum that allow individual thylakoid lumens to form a single, contiguous compartment
e.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
f.the molecule used to store carbon overnight in CAM plants
g.organisms that use CO₂ as their carbon source and light as their energy source
photophosphorylation

Question 66

Match each term with its definition.
a.the generation of ATP via a proton gradient created by light-energized electrons moving down an electron transport chain
b.the site of the light-independent reactions in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid and stromal membranes of chloroplasts
d.membranous connections between granum that allow individual thylakoid lumens to form a single, contiguous compartment
e.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
f.the molecule used to store carbon overnight in CAM plants
g.organisms that use CO₂ as their carbon source and light as their energy source
photorespiration

Question 67

Match each term with its definition.
a.the generation of ATP via a proton gradient created by light-energized electrons moving down an electron transport chain
b.the site of the light-independent reactions in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid and stromal membranes of chloroplasts
d.membranous connections between granum that allow individual thylakoid lumens to form a single, contiguous compartment
e.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
f.the molecule used to store carbon overnight in CAM plants
g.organisms that use CO₂ as their carbon source and light as their energy source
malate

Question 68

Match the name of the process to its description.
a.noncyclic electron flow
b.cyclic electron flow
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of Calvin cycle
e.RuBP regeneration stage of Calvin cycle
This is when the G3P product is actually synthesized in the chloroplast.

Question 69

For each phrase, choose the most appropriate process.
a.light-dependent reactions only
b.Calvin cycle only
c.light-dependent reactions and the Calvin cycle both
d.neither the light-dependent reactions nor the Calvin cycle
produces ATP

Question 70

For each phrase, choose the most appropriate process.
a.light-dependent reactions only
b.Calvin cycle only
c.light-dependent reactions and the Calvin cycle both
d.neither the light-dependent reactions nor the Calvin cycle
produces NADP⁺

Question 71

Match each term with its definition.
a.the generation of ATP via a proton gradient created by light-energized electrons moving down an electron transport chain
b.the site of the light-independent reactions in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid and stromal membranes of chloroplasts
d.membranous connections between granum that allow individual thylakoid lumens to form a single, contiguous compartment
e.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
f.the molecule used to store carbon overnight in CAM plants
g.organisms that use CO₂ as their carbon source and light as their energy source
stromal lamellae

Question 72

Match the name of the process to its description.
a.noncyclic electron flow
b.cyclic electron flow
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of Calvin cycle
e.RuBP regeneration stage of Calvin cycle
This form of the light-dependent reactions produces ATP and NADPH in equal molar ratios.

Question 73

Match each term with its definition.
a.the generation of ATP via a proton gradient created by light-energized electrons moving down an electron transport chain
b.the site of the light-independent reactions in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid and stromal membranes of chloroplasts
d.membranous connections between granum that allow individual thylakoid lumens to form a single, contiguous compartment
e.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
f.the molecule used to store carbon overnight in CAM plants
g.organisms that use CO₂ as their carbon source and light as their energy source
stroma

Question 74

Match the name of the process to its description.
a.noncyclic electron flow
b.cyclic electron flow
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of Calvin cycle
e.RuBP regeneration stage of Calvin cycle
This reaction uses rubisco, the most abundant enzyme on Earth.

Question 75

For each phrase, choose the most appropriate process.
a.light-dependent reactions only
b.Calvin cycle only
c.light-dependent reactions and the Calvin cycle both
d.neither the light-dependent reactions nor the Calvin cycle
requires glucose

Question 76

For each phrase, choose the most appropriate process.
a.light-dependent reactions only
b.Calvin cycle only
c.light-dependent reactions and the Calvin cycle both
d.neither the light-dependent reactions nor the Calvin cycle
requires rubisco

Question 77

Match the name of the process to its description.
a.noncyclic electron flow
b.cyclic electron flow
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of Calvin cycle
e.RuBP regeneration stage of Calvin cycle
This converts G3P into a molecule that can bind to CO₂.

Question 78

For each phrase, choose the most appropriate process.
a.light-dependent reactions only
b.Calvin cycle only
c.light-dependent reactions and the Calvin cycle both
d.neither the light-dependent reactions nor the Calvin cycle
produces O₂

Question 79

For each phrase, choose the most appropriate process.
a.light-dependent reactions only
b.Calvin cycle only
c.light-dependent reactions and the Calvin cycle both
d.neither the light-dependent reactions nor the Calvin cycle
consumes O₂

Question 80

Match each term with its definition.
a.the generation of ATP via a proton gradient created by light-energized electrons moving down an electron transport chain
b.the site of the light-independent reactions in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid and stromal membranes of chloroplasts
d.membranous connections between granum that allow individual thylakoid lumens to form a single, contiguous compartment
e.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
f.the molecule used to store carbon overnight in CAM plants
g.organisms that use CO₂ as their carbon source and light as their energy source
photosystems