Deck 8: Photosynthesis

Question 1

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.

Answer 1

B

Question 2

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 ​

Answer 2

E

Question 3

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 (ultra violet and infrared). ​

Answer 3

D

Question 4

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 5

Where does photosynthesis take place in cyanobacteria?

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

Question 6

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

A)O₂
B)CO₂ ​
C)H₂O ​
D)H⁺ ​
E)C₆H₁₂O₆

Question 7

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 8

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

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

Question 9

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 ​

Question 10

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 11

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 O₂ release in photosynthesis; dependent = absorption of light ​
D)independent = wavelength; dependent = rate of O₂ release in photosynthesis ​
E)independent = rate of O₂ release in photosynthesis; dependent = wavelength ​

Question 12

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 electron release energy in the form of a photon
B)the excited electrons are transferred to an electron donor molecule ​
C)the excited electrons  revert back 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 13

Which plant structure is responsible for gas exchange? ​

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

Question 14

Where does photosynthesis occur in plant cells?

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

Question 15

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 are heterotrophs and thus make no contribution to the flow of energy into the ecosystem. ​

Question 16

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 17

If photosynthetic eukaryotic cells are provided with CO₂ synthesized with heavy oxygen (¹⁸O), the ¹⁸O label may be found in all but one compound. That compound is ____. ​

A)3-phosphoglycerate
B)cellulose ​
C)glucose ​
D)O₂ gas ​
E)RuBP (ribulose bisphosphate)

Question 18

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 19

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 20

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 ​

Question 21

Where does the Calvin cycle occur?

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

Question 22

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 23

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 CO₂ is unavailable and the Calvin cycle is not operating ​
E)to increase the net production of ATP in times when CO₂ is unavailable ​

Question 24

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 25

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

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

Question 26

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 27

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 28

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 29

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 30

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 31

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

A)provide electrons and energy for the light-independent reactions
B)generate O₂ gas ​
C)make ADP in cyclic photophosphorylation ​
D)transfer electrons to the primary electron acceptors ​
E)produce sugars such as glucose ​

Question 32

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 33

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 CO₂ levels were low? ​

A)RuBP only reacts with CO₂ in the sunlight.
B)RuBP only reacts with CO₂ when 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)CO₂ serves as a non-competitive inhibitor of rubisco.

Question 34

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 35

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 CO₂ concentrations (global warming)​
E)generate the O₂ gas required for cellular respiration ​

Question 36

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

A)atmospheric CO₂  must be oxidized by adding electrons
B)CO₂ must 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 37

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 38

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

A)ADP and NADP⁺
B)water, O₂, ATP. ​
C)CO₂ and RuBP ​
D)electrons and photons ​
E)ATP and NADPH ​

Question 39

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 40

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 41

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 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 CO₂ from entering the leaf. ​
D)The rubisco enzyme is very temperature sensitive and becomes less efficient in warmer temperatures, allowing it to fix O₂ instead 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

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 44

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 45

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

A)Rubisco is more efficient in C₃ plants when compared to rubisco of C₄ and 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 CO₂ taken in during the night. ​
D)There is an energetic cost to C₄ and 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 46

Rubisco has 16 subunits joined together to make a functional unit. Eight of the subunits are large, the other 8 are small. On which subunit(s)is/are the active sites located? ​

A)on each of the 8 large subunits
B)on each of the 8 small subunits ​
C)on one of the 8 large subunits ​
D)on one of the 8 small subunits ​
E)on each of the 16 subunits

Question 47

Rubisco has 16 subunits joined together to make a functional unit. Eight of the subunits are large, the other 8 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 48

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

A)2
B)3 ​
C)6 ​
D)12 ​
E)24 ​

Question 49

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 50

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 51

When does a C₄ plant use rubisco?

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

Question 52

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 53

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 54

The process by which CO₂ is released through the oxygenase activity of rubisco is called ____.

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

Question 55

Rubisco has 16 subunits joined together to make a functional unit. Eight of the subunits are large, the other 8 are small. On which subunit(s)is/are the active sites located? ​

A)on each of the 8 large subunits
B)on each of the 8 small subunits ​
C)on one of the 8 large subunits ​
D)on one of the 8 small subunits ​
E)on each of the 16 subunits

Question 56

In the C₄ pathway, which molecule is formed after the addition of CO₂ to PEP? ​

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

Question 57

The C₄ cycle ____.

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 CO₂ is provided to rubisco and thus prevents photorespiration ​
E)is most commonly associated with plants living in humid climates ​

Question 58

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 59

I'm a botanist looking for new species of C₄ plants. Where should I focus my search?

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

Question 60

Which molecule associated with photorespiration is toxic to plant cells? ​

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

Question 64

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 70

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 71

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 78

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 80

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 ​