Deck 8: Photosynthesis

Question 1

The action spectrum of higher plants is bimodal, with two major peaks. Which two molecules largely determine the two peaks?

A) photosystems I and II
B) P680 and P700
C) chlorophyll a and chlorophyll b
D) chlorophyll and carotenoid
E) ATP and NADH

Answer 1

C

Question 2

What is the source of electrons for carbon fixation in plants?

A) O₂
B) CO₂
C) H₂O
D) H⁺
E) C₆H₁₂O₆

Answer 2

C

Question 3

The molecule of chlorophyll a in photosystem II's reaction center is known as P680 because ____.

A) it absorbs 680 photons per minute
B) it absorbs photons with a wavelength of 680 nm
C) there are exactly 680 accessory pigments in the photosystem
D) it will generate 680 molecules of ATP per photon absorbed
E) there are 680 electrons that can be energized by light

Answer 3

B

Question 4

In any experiment, changes to the dependent variable based on the manipulations of the independent variable are measured. When determining the action spectrum of a given plant, what is the independent variable and what is the dependent variable?

A) independent = absorption of light; dependent = wavelength
B) independent = wavelength; dependent = absorption of light
C) independent = rate of O₂release in photosynthesis; dependent = absorption of light
D) independent = wavelength; dependent = rate of O₂release in photosynthesis
E) independent = rate of O₂release in photosynthesis; dependent = wavelength

Question 5

Where does photosynthesis occur in plant cells?

A) plasma membrane
B) Golgi bodies
C) cytosol
D) mitochondria
E) chloroplasts

Question 6

Which statement correctly summarizes the two phases of photosynthesis?

A) The light-dependent reactions occur in the cytosol; the light-independent reactions occur in the stroma.
B) The products of the light-dependent reactions are ATP, NADPH, and O₂; the products of the light-independent reactions are ADP, NADP⁺, and sugar.
C) The light-dependent reactions occur only during the daylight hours; the light-independent reactions occur only when it is dark.
D) The light-dependent reactions produce water as a by-product; the light-independent reactions produce carbon dioxide as a waste product.
E) The products of the light-dependent reactions are ADP, NADP⁺, and O₂; the products of the light-independent reactions are ATP, NADPH, and sugar.

Question 7

The chemical structure of chlorophyll is based on a complex organic ring structure, with a long hydrophobic side chain and a(n) ____ atom in the center of the ring.

A) carbon
B) manganese
C) magnesium
D) iron
E) nitrogen

Question 8

Where can you find ATP synthase in a plant cell?

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

Question 9

Suppose you explored a new planet and found a photosynthetic organism unlike any on Earth. 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. What does this tell you?

A) The sun of this new planet emits different wavelengths of light than our own.
B) This new organism is using yellow and green light to drive photosynthesis.
C) This organism appears green, just like plants on Earth.
D) This organism utilizes the most energy-rich photons of the spectrum.
E) This new organism is using blue and red light to drive photosynthesis.

Question 10

Which characteristic of the light absorbing regions of chlorophylls and carotenoids most likely accounts for the ability of these molecules to absorb light?

A) ringed structures
B) the presence of aldehyde side-groups
C) the presence of magnesium
D) an extensive network of double bonds
E) long hydrocarbon chain

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) Chlorophyll is green and thus reflects green light.
B) The bacteria were immobile and that is where Engelmann happened to place them.
C) Photosynthesis is most active in those wavelengths of light and thus more oxygen is consumed by the algae in those regions.
D) Photosynthesis is most active in those wavelengths of light and thus more oxygen is produced by the algae in those regions.
E) The most energy-rich wavelengths of light are found at the edges of visible and nonvisible light (ultraviolet and infrared).

Question 12

If photosynthetic eukaryotic cells are provided with CO₂synthesized with heavy oxygen (¹⁸O), the¹⁸O label may be found in all but one compound. That compound is ____.

A) 3-phosphoglycerate
B) cellulose
C) glucose
D) O₂gas
E) RuBP (ribulose bisphosphate)

Question 13

Fluorescence occurs when ____.

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

Question 14

When a photon of light is absorbed by a pigment molecule, electrons jump to an excited state. What is one possible fate of these excited electrons?

A) The excited electrons release energy in the form of a photon.
B) The excited electrons are transferred to an electron donor molecule.
C) The excited electrons revert to their ground state without releasing any energy.
D) The excited electrons jump to a lower energy level, releasing energy to a nearby pigment molecule.
E) The excited electrons jump to a lower energy level, releasing energy in the form of ATP.

Question 15

Where does photosynthesis take place in cyanobacteria?

A) plasma membrane
B) Golgi bodies
C) cytosol
D) mitochondria
E) chloroplasts

Question 16

In higher plants, thylakoids are arranged into stacks called ____.

A) stroma
B) stomata
C) photosystems
D) grana
E) stromal lamellae

Question 17

Which statement describes the role of photosynthesis in an ecosystem?

A) Primary producers convert chemical energy to light energy.
B) Primary consumers rely directly on light energy.
C) Primary producers convert light energy to chemical energy as a service to the ecosystem, not for their own gain.
D) Primary consumers rely on primary producers to make light energy available in a usable form.
E) Primary producers make no contribution to the flow of energy into the ecosystem.

Question 18

If you want to buy a colored light bulb for your indoor plants, which color would be the least effective?

A) red
B) blue
C) green
D) yellow
E) orange

Question 19

Which of these waves has the longest wavelength?

A) blue visible light
B) gamma rays
C) UV rays
D) x-rays
E) red visible light

Question 20

Which plant structure is responsible for gas exchange?

A) stroma
B) stomata
C) thylakoid
D) grana
E) stromal lamellae

Question 21

What is the fate of electrons from NADPH during the Calvin cycle?

A) They are accepted by molecular oxygen, just like in cellular respiration.
B) They are used to regenerate RuBP from G3P
C) They are added to 3PGA.
D) They are transferred to rubisco.
E) They remain on NADPH to help drive the light reactions

Question 22

What is the purpose of cyclic electron flow?

A) to prevent the formation of NADPH and excessive reactive oxygen species
B) to prevent the loss of light energy when the ATP production pathway is saturated
C) to ensure that all of the energy harvested by the sun is converted into ATP
D) to protect the cell when CO₂is unavailable and the Calvin cycle is not operating
E) to increase the net production of ATP in times when CO₂is unavailable

Question 23

P700 is located in photosystem ____ and is comprised of chlorophyll ____.

A) I; b
B) I; a
C) II; b
D) II; a
E) I and II; a

Question 24

Photosynthesis must provide a source of electrons and H⁺because ____.

A) atmospheric CO₂ must be oxidized by adding electrons
B) CO₂must be reduced to produce sugars
C) hydrogen atoms are added to oxygen to form water
D) hydrogen ions and electrons react to produce hydrogen gas
E) hydrogen ions and electrons are converted into oxygen gas

Question 25

The synthesis of ATP coupled to the transfer of electrons energized by photons of light is called ____.

A) photosynthesis
B) photophosphorylation
C) phosphorylative oxidation
D) photorespiration
E) oxidative phosphorylation

Question 26

In order to understand the driving force of ATP synthase in chloroplasts, researchers broke open chloroplasts, isolated the thylakoid membrane and measured ATP synthesis under different light conditions. What were the results of this experiment?

A) ATP production occurred only in light, suggesting that the light is directly responsible for the activation of ATP synthase.
B) ATP production occurred only in light, suggesting that the light is indirectly responsible for the activation of ATP synthase.
C) ATP production occurred only in dark, suggesting that the light directly inhibits ATP synthase.
D) ATP production occurred only in dark, suggesting that the photons of light act as allosteric (non-competitive) inhibitors of ATP synthase.
E) ATP production occurred only in dark, suggesting that the light is indirectly responsible for the activation of ATP synthase.

Question 27

The primary purpose of the light-dependent reactions is to ____.

A) provide electrons and energy for the light-independent reactions
B) generate O₂gas
C) make ADP in cyclic photophosphorylation
D) transfer electrons to the primary electron acceptors
E) produce sugars such as glucose

Question 28

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

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

Question 29

Which plant cell structure is comprised of approximately 300 chlorophyll molecules and about 40 carotenoid pigments, organized together to optimize the capture of light energy?

A) reaction center
B) chlorophyll
C) antenna complex
D) cytochrome complex
E) stomata

Question 30

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

A) ADP and NADP⁺
B) water, O₂, ATP
C) CO₂and RuBP
D) electrons and photons
E) ATP and NADPH

Question 31

2D chromatography is so named because ____.

A) there are two steps: labeling with a radioactive marker and separation via chromatography
B) the molecules are separated into a linear arrangement, meaning two dimensions
C) the process separates the molecules in two directions, first along the x axis and then along the y axis
D) two different solutions are used in the paper chromatography process
E) two different types of radioactive markers must be used

Question 32

Which molecule(s) regulate(s) photosynthesis by sensing the metabolic status of the chloroplast and regulating proton flow out of the thylakoid lumen?

A) ATP synthase
B) chlorophyll a
C) chlorophyll b
D) carotenoids
E) the antenna complex

Question 33

In the light-dependent reactions of photosynthesis, an excited electron from photosystem II is passed along an electron transport chain to ____.

A) NAD⁺
B) NADH
C) photosystem I
D) oxygen
E) water

Question 34

The purpose of the Calvin cycle is to ____.

A) convert inorganic carbon into a useable form of carbon
B) recover electrons lost when water was split
C) capture photons of light to harvest solar energy
D) counteract increasing atmospheric CO₂concentrations (global warming)
E) generate the O₂gas required for cellular respiration

Question 35

Where does the Calvin cycle occur?

A) thylakoid membrane
B) thylakoid lumen
C) stromal lamellae
D) cytosol
E) stroma

Question 36

Chloroplasts kept in the dark can continue to make sugar if provided with ____.

A) NADPH, ATP, and CO₂
B) NADPH and ATP
C) CO₂and ATP
D) NADPH, CO₂, and ADP
E) water and ATP

Question 37

In order to elucidate the Calvin cycle, Calvin and his colleagues used two-dimensional paper chromatography to analyze the presence of different molecules under different conditions. What did they conclude from the accumulation of RuBP when CO₂levels were low?

A) RuBP only reacts with CO₂in the sunlight.
B) RuBP only reacts with CO₂when concentrations of ATP are low.
C) RuBP is the first substrate to react with CO_2.
D) RuBP is the last substrate to react in the Calvin cycle.
E) CO₂serves as a non-competitive inhibitor of rubisco.

Question 38

What is the correct order of the three phases of the Calvin cycle?

A) carbon fixation, oxidation, regeneration
B) carbon fixation, reduction, regeneration
C) carbon fixation, regeneration, oxidation
D) carbon fixation, regeneration, reduction
E) oxidation, carbon fixation, regeneration

Question 39

What is the purpose of the third phase of the Calvin cycle?

A) carbon fixation
B) generation of ATP
C) reduction of NADPH
D) oxidation of NADPH
E) regeneration of RuBP

Question 40

In 2D chromatography analysis, each of the spots on the chromatography paper represent different proteins. In order to correctly identify the proteins and interpret the data, which experimental control must be included?

A) using cellular carbohydrate extract that was not labeled with radioactivity to determine the effect of radioactive labeling on the study
B) using purified proteins of interest in individual trials to identify each protein's profile on the chromatography paper
C) using water in place of the cellular carbohydrate extract to compare the profile of the proteins to a completely pure sample
D) using water in place of the solvent to determine the effect of the solvent on the movement of the proteins on the chromatography paper
E) removing excess proteins from the cellular carbohydrate extract before chromatography

Question 41

Malate produced by the CAM pathway in CAM plants ____.

A) is immediately used in cellular respiration
B) is stored during the night in the central vacuole
C) is stored during the day in the stroma
D) diffuses to bundle sheath cells for degradation in the lysosomes
E) is stored in mesophyll cells

Question 42

Why is photorespiration more likely to occur during 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 nighttime than during the day.
C) Plants are more likely to dehydrate in warm weather, forcing them to close the stomata to conserve water, thus preventing CO₂from entering the leaf.
D) The rubisco enzyme is very temperature sensitive and becomes less efficient in warmer temperatures, allowing it to fix O₂instead of CO₂.
E) Plants use up the water in their central vacuoles in warm weather, inhibiting the water-requiring light reactions; this in turn alters the activity of rubisco.

Question 43

Why isn't the oxygenase function of rubisco active under normal environmental conditions?

A) The oxygenase activity of the enzyme requires more energy.
B) The affinity of the enzyme favors the binding of CO₂.
C) The oxygenase activity of the enzyme is inhibited by O₂.
D) The binding site of the enzyme is allosterically inhibited under normal conditions.
E) The oxygenase binding site has a higher affinity for ATP.

Question 44

If a plant synthesized a molecule of sugar that has 12 carbons, how many turns of the Calvin cycle would be needed?

A) two
B) three
C) six
D) 12
E) 24

Question 45

If you were to extract all of the proteins from a leaf and measure the composition of rubisco, you would find that it comprises about ____% of the total leaf protein.

A) 10
B) 25
C) 50
D) 75
E) 90

Question 46

When does a CAM plant use rubisco?

A) daytime only
B) nighttime only
C) summer only
D) winter only
E) anytime the Calvin cycle is occurring

Question 47

The C₄cycle ____.

A) replaces the second stage of the Calvin cycle
B) supplements the activity of rubisco by providing a second source of 3PGA for the reduction stage of the Calvin cycle
C) is more efficient than the Calvin cycle because less ATP is consumed in the process
D) ensures that CO₂is provided to rubisco and thus prevents photorespiration
E) is most commonly associated with plants living in humid climates

Question 48

Rubisco has 16 subunits joined together to make a functional unit. Eight of the subunits are large, the other eight are small. What is the function of the small subunits?

A) The small subunits contain the reactant binding sites.
B) They stabilize the overall enzyme's structure but have no intrinsic function.
C) The function of the small subunits is still unknown.
D) They regulate the enzyme's rate of catalysis.
E) The small subunits contain allosteric regulator binding sites.

Question 49

I'm a botanist looking for new species of C₄plants. Where should I focus my search?

A) Maine
B) Quebec, Canada
C) equatorial rainforest
D) The Everglades (in Florida)
E) Arizona

Question 50

In the C₄pathway, which molecule is formed after the addition of CO₂to PEP?

A) phosphoenolpyruvate
B) malate
C) oxaloacetate
D) pyruvate
E) 3PGA

Question 51

Rubisco has 16 subunits joined together to make a functional unit. Eight of the subunits are large, the other eight are small. On which subunit(s) is/are the active sites located?

A) on each of the eight large subunits
B) on each of the eight small subunits
C) on one of the eight large subunits
D) on one of the eight small subunits
E) on each of the 16 subunits

Question 52

The process by which CO₂is released through the oxygenase activity of rubisco is called ____.

A) photosynthesis
B) photophosphorylation
C) phosphorylative oxidation
D) photorespiration
E) oxidative phosphorylation

Question 53

Which phase(s) of the Calvin cycle require ATP?

A) phase I only
B) phase II only
C) phase III only
D) phases I and II only
E) phases II and III only

Question 54

Which molecule associated with photorespiration is toxic to plant cells?

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

Question 55

As temperatures rise, photorespiration activity ____, because gas exchange via the ____ is inhibited.

A) increases; grana
B) decreases; grana
C) increases; stroma
D) decreases; stroma
E) increases; stomata

Question 56

C₃plants are more susceptible to photorespiration than either C₄or CAM plants. Why do most plants lack the C₄pathway?

A) Rubisco is more efficient in C₃plants when compared to rubisco of C₄and CAM plants.
B) Photorespiration is not a serious problem for most plants.
C) Most plant species do not have vacuoles in their cells to store the malate generated from CO₂taken in during the night.
D) There is an energetic cost to C₄and CAM pathways that only makes them advantageous in very hot and/or arid environments.
E) Switching between C₃, C₄, and CAM photosynthesis is very difficult for most plants.

Question 57

When does a C₄plant use rubisco?

A) daytime only
B) nighttime only
C) summer only
D) winter only
E) anytime the Calvin cycle is occurring

Question 58

Rubisco functions as both a(n) ____ and a(n) ____.

A) enzyme; substrate
B) enzyme; product
C) carboxylase; kinase
D) carboxylase; phosphatase
E) carboxylase; oxygenase

Question 59

What is the most common form in which the products of photosynthesis circulate from cell to cell in vascular plants?

A) glucose
B) sucrose
C) cellulose
D) fructose
E) amylose

Question 60

Why is Rubisco present in high concentrations in leaves?

A) to compensate for its low rate of catalysis
B) because it has a high rate of catalysis
C) because it has eight large subunits
D) because it has eight small subunits
E) because it is not a regulatory site

Question 62

Which event probably made the evolution of cellular respiration possible?

A) accumulation of carbon dioxide in atmosphere
B) emergence of prokaryotes
C) accumulation of oxygen in atmosphere
D) emergence of eukaryotes
E) emergence of plants

Question 64

Photosystem II functions before photosystem I in the linear flow of electrons.

Question 65

Why do the photosynthetic tissues of plants look green?

Question 66

When does a CAM plant take in atmospheric CO₂?

A) daytime only
B) nighttime only
C) summer only
D) winter only
E) anytime the Calvin cycle is occurring

Question 67

Carbon fixation is a reduction reaction that converts inorganic CO₂into an organic molecule.

Question 68

Explain the following statement: Nearly all life on Earth ultimately depends on the sun for energy.

Question 69

What is a major similarity and difference between photorespiration and aerobic respiration?

Question 70

Photosynthesis occurs in ____, while cellular respiration occurs in ____.

A) plants; animals
B) animals; plants
C) plants and animals; animals
D) plants; plants and animals
E) plants and animals; plants and animals

Question 71

Cyclic electron flow generates ATP and O₂, but not NADPH.

Question 72

The Calvin cycle is sometimes referred to as the C₃pathway because it generates a single three-carbon molecule for every three turns of the cycle.

Question 73

Atmospheric O₂is a waste product of photosynthesis.

Question 74

The beautiful fall leaves get their orange and yellow colors from carotenoids.

Question 75

Why isn't oxygen produced by organisms that perform anoxygenic photosynthesis?

A) Their photosystems do not utilize the Calvin cycle.
B) They use a different enzyme for the initial reactions of the Calvin cycle.
C) They use electron donors other than water.
D) Their membranes lack ATP synthase.
E) Their chlorophyll contains an iron center rather than magnesium.

Question 76

Photosynthesis is ____, while all other processes of life are ____.

A) exergonic; exothermic
B) endergonic; endothermic
C) endergonic; exergonic
D) exergonic; endergonic
E) exergonic; endothermic

Question 77

Orchids, which grow well in regions that are hot and dry during the day and cool at night, are classified as CAM plants.

Question 78

The loss of O₂in the atmosphere 600-800 million years ago was likely due to the "fossilization" of organic matter trapped in Earth's crust.

Question 79

Rubisco's enzymatic activity is stimulated by NADP⁺and ADP.

Question 80

In photorespiration, there is a net gain of carbon.