Deck 8: Photosynthesis: Using Sunlight to Build Carbohydrates

Question 1

Photosynthesis is the pathway used to synthesize carbohydrates from:

A)sunlight.
B)carbon dioxide.
C)oxygen.
D)sunlight, carbon dioxide, and water.
E)sunlight, carbon dioxide, and oxygen.

Answer 1

D

Question 2

Where is the photosynthetic electron transport chain located in plant cells?

A)in the inner membrane of the chloroplast
B)in the outer membrane of the chloroplast
C)in the stroma of the chloroplast
D)in the thylakoid membranes of the chloroplast

Answer 2

D

Question 3

In plants and algae, _____ is the source of the electrons needed for photosynthesis.

A)O₂
B)CO₂
C)H₂O
D)NADPH
E)H⁺

Answer 3

C

Question 4

In plants and algae, which of the following is a by-product of photosynthesis?

A)O₂
B)CO₂
C)carbohydrates
D)C₆H₁₂O₆
E)H⁺

Question 5

Photosynthesis occurs in the layer of the ocean penetrated by sunlight, which is referred to as the _____ zone.

Question 6

In terms of energy production, humans have nothing in common with plants.

Question 7

Explain the relationship between cellular respiration and photosynthesis with respect to the storage and release of chemical energy.

Question 8

During photosynthesis in plants and algae, _____ is oxidized and _____ is reduced.

A)O₂; CO₂
B)CO₂; H₂O
C)H₂O; O₂
D)H₂O; CO₂
E)NADPH; ATP

Question 9

In plants, the ultimate electron donor in photosynthesis is _____.

Question 10

Which of the following sequences CORRECTLY represents the flow of energy through living systems?

A)light  photosynthesis  carbohydrate  cellular respiration  ATP  heat
B)water  photosynthesis  carbohydrate  cellular respiration  ATP  CO₂
C)water  photosynthesis  carbohydrate  cellular respiration  ATP  water
D)light  photosynthesis  carbohydrate  cellular respiration  ATP  water
E)CO₂  photosynthesis  carbohydrate  cellular respiration  ATP  heat

Question 11

In the chloroplasts of plant cells, the absorption of light energy and the movement of electrons along an electron transport chain occurs in the _____ and the synthesis of carbohydrates takes place in the _____.

A)thylakoids; stroma
B)inner membrane; matrix
C)thylakoids; matrix
D)inner membrane; cytoplasm
E)inner membrane; stroma

Question 12

Eukaryotes conduct all of the photosynthesis that occurs in the ocean.

Question 13

During photosynthesis, _____ is reduced to _____.

A)water; carbon dioxide
B)carbon dioxide; sugar
C)oxygen; water
D)sugar; oxygen
E)carbon dioxide; oxygen

Question 14

As in mitochondria, the inner membrane of a chloroplast is highly convoluted, greatly increasing surface area.

Question 15

The fluid-filled interior compartment of the thylakoid network is referred to as the:

A)stroma.
B)grana.
C)cytoplasm.
D)lumen.
E)intermembrane space.

Question 16

Not all photosynthetic organisms are plants, but one thing they all have in common is that they can only be found within a narrow temperature and moisture range.

Question 17

Prokaryotes account for roughly half of terrestrial photosynthesis.

Question 18

Which one of the following statements BEST represents the relationship between cellular respiration and photosynthesis?

A)Photosynthesis stores energy in organic molecules, while respiration releases it.
B)Photosynthesis occurs only during the day and respiration occurs only at night.
C)Respiration occurs only in animals and photosynthesis occurs only in plants.
D)Respiration stores energy in organic molecules, while photosynthesis releases it.
E)Photosynthesis reverses the biochemical pathways of respiration.

Question 19

The experiment in Fig. 8.3 demonstrates that the percentage of ¹⁸O₂ increases when the:

A)water in the experiment contains ¹⁸O₂.
B)carbon dioxide in the experiment contains ¹⁸O₂.
C)water and carbon dioxide in the experiment both contain ¹⁸O₂.

Question 20

Which of the following are produced directly as a result of the movement of electrons through the photosynthetic electron transport chain?

A)oxygen and carbohydrates
B)carbohydrates and ATP
C)ATP and NADPH
D)water and carbohydrates

Question 21

Which of the following is TRUE concerning the Calvin cycle and light-harvesting reactions of photosynthesis?

A)They take place in different organelles.
B)They take place in different compartments of the same organelle.
C)They take place in different types of cells in the plant.
D)None of the other answer options is correct.

Question 22

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a decrease in NADPH production in the chloroplasts. (Interestingly, reduction of NAD⁺ to NADH in the mitochondria is unaffected.) Given this observation, what specific change(s), if any, would you expect to observe in the amounts of ATP, 3-phosphoglycerate and glyceraldehyde-3-phosphate, and RuBP in the chloroplasts of these plants?

Question 23

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a decrease in ATP production in the chloroplasts. (Interestingly, production of ATP in the mitochondria is unaffected.) Given this observation, which of the following would you expect to be DIRECTLY affected by the new pesticide?

A)the synthesis of triose phosphates from 3-phosphoglycerate
B)the transport of electrons along the photosynthetic electron transport chain
C)the carboxylation of RuBP by rubisco
D)the oxidation of RuBP by rubisco

Question 24

Where does the oxygen come from that is produced as a by-product of photosynthesis?

A)from the reduction of CO₂
B)from breakdown of water
C)from the breakdown of carbohydrates
D)from the Calvin cycle

Question 25

In animal cells, most ATP synthesis takes place in mitochondria, but in plant cells, most of the ATP used by plant cells is made in the chloroplasts.

Question 26

All cells able to carry out photosynthesis have:

A)chloroplasts.
B)mitochondria.
C)a plasma membrane.
D)chloroplasts and mitochondria.
E)chloroplasts, mitochondria, and a plasma membrane.

Question 27

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a decrease in ATP production in the chloroplasts. (Interestingly, production of ATP in the mitochondria is unaffected.) Given this observation, which of the following would you expect to be DIRECTLY affected by the new pesticide?

A)the rate of photorespiration
B)the transport of electrons along the photosynthetic electron transport chain
C)the carboxylation of RuBP by rubisco
D)the oxidation of RuBP by rubisco

Question 28

Which product(s) of the Calvin cycle is (are) exported from the chloroplast for use by the plant cell?

A)triose phosphates
B)sucrose and glucose
C)RuBP
D)NADPH

Question 29

A researcher is carrying out an experiment where she labels a protein with a fluorescent tag (so she can visualize its location in a cell), and introduces this tagged protein into the lumen of a single thylakoid. She observes her treated cells periodically, and notices that the labeled protein can move between grana, but is never observed in the stroma. What can she deduce?

A)This protein can easily transfer between the inner and outer mitochondria membranes.
B)All thylakoid membranes and grana share a common lumen, through which the labeled protein can move.
C)This protein likely travels between different thylakoid membranes by moving through the stroma, but its movement through the stroma is very brief.
D)This protein cannot easily diffuse through the thylakoid membrane.
E)The protein likely travels through a common lumen shared by thylakoid membranes and grana, and cannot easily diffuse through the thylakoid membrane.

Question 30

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a decrease in NADPH production in the chloroplasts. (Interestingly, reduction of NAD⁺ to NADH in the mitochondria is unaffected.) Given this observation, which of the following would you expect to observe in the chloroplasts of these plants?

A)an increase in 3-phosphoglycerate levels and a decrease in RuBP production
B)a decrease in 3-phosphoglycerate levels and an increase in RuBP production
C)an increase in glyceraldehyde-3-phosphate production
D)an increase in 3-phosphoglycerate production and an increase in RuBP production

Question 31

In photosynthesis, the electrons from _____ are used to reduce _____.

A)water; carbon dioxide
B)oxygen; carbohydrates
C)oxygen; NADPH
D)water; carbohydrates

Question 32

Review the experiment illustrated in Fig. 8.6. Based on the result of Experiment #2 and on what you know about photosynthesis, draw the 2D chromatography pattern that would be observed if the cells treated with ¹⁴CO₂ had been allowed to remain in culture for a longer period of time before they were put in the boiling alcohol. Label the dot(s) appropriately on your drawing using the labels in Fig. 8.6 as a reference.

Question 33

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a decrease in NADPH production in the chloroplasts. (Interestingly, reduction of NAD⁺ to NADH in the mitochondria is unaffected.) Given this observation, what specific change(s), if any, would you expect to observe in the intermediate compounds of photosynthesis in the chloroplasts of these plants?

Question 34

Name the product of the Calvin cycle that is exported from the chloroplast for use by the plant cell.

Question 35

Two petri dishes of radish seeds are prepared as follows: a disk of absorbent, but otherwise inert, filter paper is placed in the bottom of each dish and 5 mL of distilled water are added to each disk, then 2 grams of dry radish seeds are spread over each moist disk. One dish is put in a dark cupboard and the other is put on a sunny windowsill. The investigator checks the dishes daily and adds water equally as needed. Seeds in both treatments germinate within 2 days. At the end of 10 days, the plant material on each petri plate is dried and weighed. The results are: - $\begin{array}{llcc} \text {- starting dry weight } &2.00g\\ \text { - sunny windowsill } &2.25g\\ \text { - dark cupboard} &1.75g\\\end{array}$

What is the MOST likely explanation for why the dark-grown seedlings lost biomass?

A)The metabolism in the cells of the seedlings increased to compensate for the lack of light energy.
B)Cellular respiration in the cells of the seedlings consumed the starch and oils present in the seeds as sources of energy.
C)Cellular respiration and ATP synthesis needed for growth does not occur as efficiently in plants in the dark as in plants exposed to light.

Question 36

The ratio of ATP to NADPH used by the Calvin cycle is approximately 3:2 (3 molar ATP used for each 2 molar NADPH). What is the MINIMUM number of these molecules required to synthesize one mole of glucose?

A)30 molar ATP + 20 molar NADPH
B)18 molar ATP + 12 molar NADPH
C)12 molar ATP + 8 molar NADPH
D)6 molar ATP + 4 molar NADPH
E)3 molar ATP + 2 molar NADPH

Question 37

How many rounds of the Calvin cycle are necessary to complete the synthesis of a 6-carbon sugar molecule? Explain your answer.

Question 38

Two petri dishes of radish seeds are prepared as follows: a disk of absorbent, but otherwise inert, filter paper is placed in the bottom of each dish and 5 mL of distilled water are added to each disk, then two grams of dry radish seeds are spread over each moist disk. One dish is put in a dark cupboard and the other is put on a sunny windowsill. The investigator checks the dishes daily and adds water equally as needed. Seeds in both treatments germinate within 2 days. At the end of 10 days, the plant material on each petri plate is dried and weighed. The results are: - $\begin{array}{llcc} \text {- starting dry weight } &2.00g\\ \text { - sunny windowsill } &2.25g\\ \text { - dark cupboard} &1.75g\\\end{array}$

How did the increased biomass in the sunlit dish arise (i.e., where did the additional mass come from and by what process)?

A)The additional mass came from the extra water present in the plant tissues due to greater photosynthetic activity.
B)The additional mass came from the hydrogen and oxygen atoms present in the water it took up during photosynthesis that it used to synthesize organic molecules.
C)The additional mass came from the carbon and oxygen atoms present in the carbon dioxide it took up during photosynthesis that it used to synthesize organic molecules.

Question 39

Collectively, most photosynthesis carried out in the ocean is performed by single-celled organisms as opposed to large, multicellular marine plants.

Question 40

The reactions of the Calvin cycle used to be referred to as the "dark reactions" of photosynthesis, implying that light was not required for this pathway to incorporate CO₂ into carbohydrate. However, in the absence of light the Calvin cycle shuts down. Which step of the Calvin cycle would be impacted FIRST by the absence of light energy?

Question 41

What is the MOST abundant protein on Earth?

A)rubisco
B)CO₂
C)3-PGA
D)NADPH

Question 42

Which of the following CORRECTLY describes the role of rubisco in the Calvin cycle?

A)Rubisco uses NADPH to reduce 3-phosphoglycerate to a three-carbon sugar.
B)Rubisco incorporates CO₂ from the atmosphere into an organic molecule.
C)Rubisco uses ATP to regenerate RUBP.
D)None of the other answer options is correct.

Question 43

Suppose a plant is exposed to a toxin that causes the thylakoid membranes to become much more permeable to protons than normal. Which of the following would be TRUE?

A)The carboxylation step of the Calvin cycle would be unaffected.
B)The reduction step of the Calvin cycle would slow down and eventually stop.
C)The regeneration step of the Calvin cycle would slow down and eventually stop.
D)The reduction and regeneration steps of the Calvin cycle would slow down and eventually stop.
E)The carboxylation and reduction steps of the Calvin cycle would slow down and eventually stop.

Question 44

Beginning with the step catalyzed by rubisco, arrange the steps in the Calvin cycle in the proper sequence in which they occur.

A)carboxylation, reduction, regeneration
B)reduction, regeneration, carboxylation
C)regeneration, carboxylation, reduction
D)carboxylation, regeneration, reduction
E)reduction, carboxylation, regeneration

Question 45

The product of the Calvin cycle is a triose-phosphate sugar that is either exported from the chloroplast or used to regenerate RUBP. How many times must each of the reactions in the Calvin cycle take place in order to complete the synthesis of one 3-carbon triose phosphate sugar molecule?

A)6
B)3
C)2
D)1

Question 46

The MOST abundant protein on Earth is thought to be:

A)chlorophyll.
B)cellulose.
C)rubisco.
D)water.
E)keratin.

Question 47

Review the experiment illustrated in Figure 8.6. Based on the result of Experiment #2 and on what you know about photosynthesis, which of the 2D paper chromatography patterns below would be observed if the cells treated with ¹⁴CO₂ had been allowed to remain in culture for a longer period of time before they were put in the boiling alcohol?

Question 48

In the Calvin cycle, NADPH is:

A)oxidized.
B)reduced.
C)phosphorylated.
D)oxidized and reduced.
E)None of the other answer options is correct.

Question 49

The reactions of the Calvin cycle used to be referred to as the "dark reactions" of photosynthesis, implying that light was not required for this pathway to incorporate CO₂ into carbohydrate. However, in the absence of light the Calvin cycle shuts down. Which of the following parts of the Calvin cycle would be impacted FIRST by the absence of light energy?

A)the reduction of 3-phosphoglycerate and the regeneration of RuBP
B)the carboxylation of RuBP and the reduction of 3-phosphoglycerate
C)the carboxylation of RuBP and the regeneration of RuBP
D)the carboxylation of RuBP and the synthesis of hexose sugars

Question 50

During photosynthesis, _____ is reduced to _____.

A)water; carbon dioxide
B)carbon dioxide; triose phosphate
C)oxygen; water
D)triose phosphate; oxygen
E)carbon dioxide; oxygen

Question 51

How many CO₂ molecules must enter the Calvin cycle for each molecule of triose phosphate that can be exported from the chloroplast?

A)1
B)3
C)5
D)6
E)12

Question 52

The Calvin cycle includes 15 enzymes, most of which are involved in:

A)RuBP carboxylation.
B)RuBP regeneration.
C)reduction.
D)starch synthesis.
E)ATP synthesis.

Question 53

Of the compounds listed below, identify which is a product of the Calvin cycle that is exported from the chloroplast for use by the plant cell, and then describe the importance of the other compounds to the metabolism of the plants.
triose phosphate, sucrose and glucose, RuBP, and NADPH

Question 54

Which step of the Calvin cycle would be affected first by a lack of NADPH?

A)carboxylation
B)reduction
C)regeneration
D)All of these choices are correct.

Question 55

Which of the following compounds is required for the carboxylation step of the Calvin cycle?

A)ATP
B)NADPH
C)RuBP
D)3-PGA
E)ATP and NADPH

Question 56

The products of the Calvin cycle are 3-carbon sugars.

Question 57

The primary reason surplus carbohydrates in plants are stored as starch is because:

A)they would otherwise be utilized as energy sources even if such energy were not needed at that time.
B)the space they occupy as carbohydrates is needed for other macromolecules.
C)energy is needed in the nucleus, and only starch is capable of being transported into the nucleus.
D)if they were left as individual monosaccharides, water would enter the cell by osmosis.
E)All of these choices represent equally important reasons why surplus carbohydrates in plants are stored as starch.

Question 58

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a decrease in NADPH production in the chloroplasts. (Interestingly, reduction of NAD⁺ to NADH in the mitochondria is unaffected.) Given this observation, which of the following would you NOT expect to observe in the chloroplasts of these plants?

A)a decrease in 3-phosphoglycerate levels and a decrease in RuBP production
B)an increase in 3-phosphoglycerate levels and an increase in RuBP production
C)a decrease in glyceraldehyde-3-phosphate production
D)a decrease in 3-phosphoglycerate production and an increase in RuBP production

Question 59

What is the INITIAL carbon input in the Calvin cycle?

A)C₆H₁₂O₆
B)triose phosphate
C)CO₂
D)rubisco

Question 60

The reducing agent during the Calvin cycle is:

A)NADPH.
B)ATP.
C)oxygen.
D)NADH.
E)FADH₂.

Question 61

The proton gradient across the thylakoid membrane is required to _____.

A)power ATP synthase
B)provide a source of protons needed to synthesize carbohydrate in the Calvin cycle
C)provide a source of protons to combine with molecular oxygen to make water
D)reduce NADP⁺ to NADPH
E)provide the energy for the reaction ADP + P_i  ATP

Question 62

How many molecules of NADPH are required for 12 molecules of RuBP to be carboxylated by rubisco?

A)10
B)12
C)24
D)36
E)None of the other answer options is correct.

Question 63

Explain why photosynthesis shuts down if the proton gradient present across the thylakoid membrane is NOT maintained.

Question 64

The pH in the stroma of the chloroplast should be _____ compared with the thylakoid lumen due to the _____ concentration of protons in the thylakoid lumen.

A)higher; higher
B)lower; higher
C)higher; lower
D)lower; lower

Question 65

Which of the following are products of the light-dependent reactions of photosynthesis that are required by reactions in the Calvin cycle?

A)ATP and oxygen
B)ATP and NADPH
C)NADP⁺ and oxygen
D)Water and NADPH

Question 66

The regeneration of RuBP typically limits the rate of photosynthesis under low light intensities. This is because:

A)RuBP regeneration requires ADP.
B)RuBP regeneration requires ATP.
C)RuBP regeneration is part of the "dark reactions."
D)photosynthesis occurs only in high light.
E)None of the other answer options is correct.

Question 67

As high-energy electrons move through the photosynthetic pathway, they take part in many oxidation/reduction reactions. Starting at the beginning of the light-dependent reactions, list in the proper sequence the molecules involved in photosynthesis that are reduced by high-energy electrons.

Question 68

When photosynthesis is fully operational under conditions of intense light, the pH of the thylakoid lumen may be as much as three full pH units lower than the stroma of the chloroplast. Does this mean that the hydrogen ion concentration in the lumen is greater or less than that of the stroma? How many more hydrogen ions are on the side of the thylakoid membrane with the higher concentration compared to the side with the lower concentration?

Question 69

ATP, NADPH, and NADH contain stored energy used by plant cells. Which of these molecules provides the energy that is stored in carbohydrate during the Calvin cycle?

A)ATP
B)NADPH
C)NADH

Question 70

During their experiments with chlorella, Calvin and Benson found no free glucose. Why do you think this is?

A)Glucose takes too long to synthesize.
B)Glucose is an isomer of fructose.
C)Glucose is stored as starch.
D)Glucose would cause H₂O to leave the chlorella cells.
E)Green algae do not respire when illuminated.

Question 71

Explain how light energy is transformed into chemical energy in the light-dependent reactions and describe where the energy is stored at the end of the light-independent reactions.

Question 72

Which of the following is needed directly to produce both triose phosphates and RuBP?

A)rubisco
B)NADPH
C)ATP
D)O₂
E)photosystem II

Question 73

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a partial inhibition of ferredoxin-NADP⁺ reductase in the chloroplasts. Given this observation, what specific change(s), if any, would you expect to observe in the amounts of NADPH, ATP, 3-phosphoglycerate and triose phosphates, and RuBP in the chloroplasts of these plants?

Question 74

Which of the following statements is TRUE regarding the Calvin cycle?

A)The Calvin cycle is considered a "dark" reaction, because it is not directly related to photosynthesis.
B)The Calvin cycle is a carefully regulated process because excess starch can be toxic to plant cells.
C)The Calvin cycle uses a rare (and thus "rate-limiting")enzyme called rubisco.
D)The action of rubisco is all that is necessary to produce high-energy triose phosphate from O₂.
E)None of the other answer options is correct.

Question 75

In the Calvin cycle, ATP is required to:

A)donate a phosphate group to 3-PGA.
B)reduce 3-PGA.
C)reduce triose phosphates.
D)carboxylate RuBP.
E)reduce RuBP.

Question 76

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is the partial inhibition of ferredoxin-NADP⁺ reductase. Given this observation, which of the following would you expect to observe in the photosynthetic cells of these plants?

A)decreased rate of triose phosphate production
B)decreased levels of NADP⁺ in the chloroplast
C)decreased levels of ATP in the chloroplast
D)decreased rate of cyclic electron transport

Question 77

For every six CO₂ molecules incorporated into carbohydrate molecules, how many triose phosphates can be exported from the chloroplast?

A)12
B)10
C)6
D)2
E)1

Question 78

In photosynthesis, the reduction of 3-phosphoglycerate to form carbohydrate requires:

A)ATP.
B)NADPH.
C)ATP and NADPH.
D)RuBP.
E)rubisco.

Question 79

The synthesis of ATP in the chloroplast by ATP synthase depends on the presence of different concentrations of protons in the lumen of the thylakoid and in the stroma. Compare these two compartments of the chloroplast in terms of both actual proton concentration and pH scale values.

Question 80

Which of the following CORRECTLY lists the three steps of the Calvin cycle?

A)carboxylation, reduction, and regeneration
B)oxidation, reduction, and carboxylation
C)carboxylation, ATP synthesis, and regeneration
D)reduction of carbon dioxide, reduction of NADPH, regeneration of RuBP