Deck 6: Photosynthesis

Question 1

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

Answer 1

B

Question 2

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.

Answer 2

C

Question 3

Which of the following are used to generate biofuels?

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

Answer 3

A

Question 4

Suppose that you found an unknown organism. You analyzed it and you found that it uses energy from light to convert CO₂ into an organic form. Based on your findings, which of the following is this organism most likely?

A) a photoautotroph
B) an autotroph
C) a heterotroph
D) a decomposer

Question 5

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 6

Suppose that you found an organism that can photosynthesize. Based on your findings, which of the following organisms could it most likely be?

A) It could be only a eukaryote.
B) It could be either an archaean, a bacterium, or a eukaryote.
C) It could be either an archaean or a eukaryote.
D) It could be either a bacterium or a eukaryote.

Question 7

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 8

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 9

Which of the following can be found in the reaction centre of a photosystem?

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 a molecules
C) a primary electron acceptor, a large number of proteins, and two chlorophyll a molecules
D) a primary electron acceptor, a small number of proteins, and two chlorophyll a molecules

Question 10

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 11

What is the primary purpose of the light reactions?

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

Question 12

Iron is required for primary production. Based on this, which of the following can be predicted?

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 13

What is the reason 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.

Question 14

Which of these pigments absorb light 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 15

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 16

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 17

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 energy

Question 18

Imagine that you are studying two basic cellular reactions: cellular respiration and photosynthesis. You have no other means to determine which one is going on but to isolate and identify two of the electron carriers involved: NAD⁺ and NADP⁺. How would these two carriers help you distinguish which cellular reaction is going on?

A) Photosynthesis uses only NADP⁺.
B) Photosynthesis uses only NAD⁺.
C) Cellular respiration can use either NADP+ or NAD+.
D) Cellular respiration uses only NADP+.

Question 19

Where does photosynthesis occur in eukaryotes?

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

Question 20

What are the reactants and products that link the light reactions to the Calvin cycle?

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

Question 21

Why is photorespiration more likely to occur in warm weather?

A) Plants require warm weather (at least 23°C) 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 22

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 23

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

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

Question 24

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 25

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 26

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) 65%

Question 27

Where in a plant cell is ATP synthase found?

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

Question 28

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

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

Question 29

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 30

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

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

Question 31

Which molecule associated with photorespiration is toxic to plant cells?

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

Question 32

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

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

Question 33

Which of these molecules is a major product of the Calvin cycle?

A) ATP
B) CO₂
C) rubisco
D) G3P

Question 34

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 35

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

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

Question 36

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 37

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

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

Question 38

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 39

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 40

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 41

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 in 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 42

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 Calvin cycle in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid membranes of chloroplasts
d.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
e.the molecule used to store carbon overnight in CAM plants
f.organisms that use CO₂ as their carbon source and light as their energy source
photoautotrophs

Question 43

In hot climates, photorespiration can decrease carbon fixation efficiently by how much?

A) by over 20%
B) by over 30%
C) by over 40%
D) by over 50%

Question 44

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 Calvin cycle in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid membranes of chloroplasts
d.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
e.the molecule used to store carbon overnight in CAM plants
f.organisms that use CO₂ as their carbon source and light as their energy source
malate

Question 45

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 46

Atmospheric O₂ is actually a waste product of photosynthesis.

Question 47

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 48

Photorespiration is even more detrimental because photoautotrophs cannot use phosphoglycolate.

Question 49

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

A) in deserts
B) in glaciers
C) in rainforests
D) in taigas

Question 50

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 Calvin cycle in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid membranes of chloroplasts
d.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
e.the molecule used to store carbon overnight in CAM plants
f.organisms that use CO₂ as their carbon source and light as their energy source
photosystems

Question 51

Glucose is the only sugar produced from photosynthesis.

Question 52

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 53

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

Question 54

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

Question 55

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

Question 56

Photosynthesis is a process by which chemical energy is converted into light energy.

Question 57

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) use it immediately
D) store it in the stroma

Question 58

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 Calvin cycle in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid membranes of chloroplasts
d.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
e.the molecule used to store carbon overnight in CAM plants
f.organisms that use CO₂ as their carbon source and light as their energy source
photophosphorylation

Question 59

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

Question 60

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

Question 61

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
requires ATP

Question 62

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
produces ATP

Question 63

Match the name of the process to its description.
a.noncyclic electron transport
b.cyclic electron transport
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of the Calvin cycle
e.RuBP regeneration stage of the Calvin cycle
The process which directly produces G3P in the chloroplast.

Question 64

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
produces ADP

Question 65

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
consumes O₂

Question 66

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
consumes NADPH

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 Calvin cycle in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid membranes of chloroplasts
d.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
e.the molecule used to store carbon overnight in CAM plants
f.organisms that use CO₂ as their carbon source and light as their energy source
photorespiration

Question 68

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
produces O₂

Question 69

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
requires glucose

Question 70

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
requires G3P to continue

Question 71

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
requires rubisco

Question 72

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 Calvin cycle in the chloroplast
c.complexes of light-absorbing molecules clustered in the thylakoid membranes of chloroplasts
d.the addition of O₂ to RuBP by rubisco, resulting in a net loss of carbon from the Calvin cycle
e.the molecule used to store carbon overnight in CAM plants
f.organisms that use CO₂ as their carbon source and light as their energy source
stroma

Question 73

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
requires water

Question 74

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

Question 75

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
creates a proton gradient

Question 76

Match the name of the process to its description.
a.noncyclic electron transport
b.cyclic electron transport
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of the Calvin cycle
e.RuBP regeneration stage of the Calvin cycle
The process which uses enzyme rubisco to create simpler sugars.

Question 77

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
occurs only during the daytime

Question 78

Match the name of the process to its description.
a.noncyclic electron transport
b.cyclic electron transport
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of the Calvin cycle
e.RuBP regeneration stage of the Calvin cycle
The process which produces both ATP and NADPH.

Question 79

If the Calvin cycle could proceed without light reactions, choose the most appropriate process for each of the two reactions.
a.only light reactions
b.only the Calvin cycle
c.both light reactions and the Calvin cycle
d.neither the light reactions nor the Calvin cycle
produces NADP⁺

Question 80

Match the name of the process to its description.
a.noncyclic electron transport
b.cyclic electron transport
c.carbon fixation stage of the Calvin cycle
d.carbon reduction stage of the Calvin cycle
e.RuBP regeneration stage of the Calvin cycle
The process which produces additional ATP for the Calvin cycle.