Deck 23: The Calvin Cycle

Question 1

In C4 plants, carbon dioxide is added to ________________ to form oxaloacetate, which is reduced to malate, which carries CO2 to the bundle-sheath cells.

Answer 1

phosphoenolpyruvate

Question 2

The binding site of Mg2+ to rubisco involves the formation of a ________________ group between lysine 221 and CO2.

Answer 2

carbamate

Question 3

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
____________ is the final enzyme in the C4 pathway.

Answer 3

f

Question 4

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
____________: A metabolic adaptation employed by plants that live in hot, dry climates.

Question 5

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
The sugar ____________, found in plants, is readily transported and easily mobilized.

Question 6

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
The enzyme ____________ is involved in both the Calvin cycle and the pentose phosphate pathway.

Question 7

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
The product of CO2 fixation with ribulose-1,6-bisphosphate is ____________.

Question 8

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
____________: Organisms that can synthesize glucose from CO2 and water.

Question 9

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
____________: These organisms obtain energy from chemical fuels.

Question 10

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
____________: The pathway that ensures that sufficient amounts of CO2 are available to minimize wasteful photorespiration.

Question 11

________________ is an example of a mechanism of accelerating photosynthesis by increasing CO2 concentration.

Question 12

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
The biochemist who first decribed the pathway for fixing CO2 is ________________.

Question 13

Plants adapt to arid ecosystems using ________________.

Question 14

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
____________ is another name for ribulose 1,5-bisphosphate carboxylase/oxygenase.

Question 15

In photorespiration, oxygen is consumed and ________________ is released .

Question 16

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
Glucose 1-phosphate, glucose 6-phosphate, and fructose 1-phosphate belong to the ____________.

Question 17

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
The enzymes that catalyze the dark reactions of photosynthesis are located in the ________________ of the chloroplasts.

Question 18

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) rubisco
b) transketolase
c) crassulacean acid metabolism
d) autotrophs
e) C6
f) pyruvate-Pi dikinase
g) hexose monophosphate pool
h) heterotrophs
i) glycolysis
j) C4
k) sucrose
l) phosphoglycerate
The first step of the Calvin cycle involves adding CO2 to ________________ to produce two molecules of 3-phosphoglycerate.

Question 19

The three stages of the Calvin cycle are ________________:

Question 20

Volcanoes, which spew millions of tons of gases and particles into the atmosphere, cause an ________________ in photosynthesis specifically during the daytime.

Question 21

What is the energy cost of the C4 pathway?

A) 30 molecules of ATP are used per hexose molecule made.
B) 18 molecules of ATP are used per hexose molecule made.
C) 30 molecules of NADPH are used per hexose molecule made.
D) 18 molecules of ATP and 12 of NADPH are used per hexose molecule made.
E) None of the above.

Question 22

________ rounds of the Calvin cycle are required for the production of hexose.

A) 1
B) 3
C) 6
D) 12
E) 9

Question 23

The immediate unwanted side-reaction of rubisco is:

A) phosphoglycolate.
B) ribulose 1,5-bisphosphate.
C) glycerol.
D) amylose.
E) phosphofructose.

Question 24

The enzyme that catalyzes the rate-limiting step in hexose synthesis is:

A) aldolase .
B) transketolase.
C) rubisco.
D) phosphopentose isomerase.
E) None of the above.

Question 25

ATP is called the energy currency. The currency of reducing power is:

A) NADPH.
B) CoA.
C) AMP.
D) ADP.
E) None of the above.

Question 26

The protein that regulates the Calvin cycle is:

A) protein kinase C.
B) rubisco.
C) thioredoxin.
D) ferredoxin-thioredoxin reductase.
E) None of the above.

Question 27

Describe the stages of the Calvin cycle.

Question 28

What is photorespiration? Why is it wasteful?

Question 29

The most abundant protein on Earth is:

A) ribulose 1,5-bisphosphate.
B) aldolase.
C) rubisco.
D) phosphopentose epimerase.
E) transketolase.

Question 30

Rubisco is found:

A) in the meso sheath bundles.
B) in the stroma of the choroplasts.
C) embedded in the plant cell wall.
D) in the lumen of the thylakoid disc.
E) None of the above.

Question 31

What is the source of carbons for the Calvin cycle?

A) glucose
B) carbon dioxide
C) glycogen
D) glyoxylate
E) None of the above.

Question 32

Why are reactions of the Calvin cycle called the "dark reactions"?

Question 33

Plants store glucose as ___________ and ____________.

A) starch; sucrose
B) fructose; sucrose
C) starch; fructose
D) All of the above.
E) None of the above.

Question 34

Which form of thioredoxin activates certain Calvin cycle enzymes?

A) reduced
B) oxidized
C) dimeric
D) A and C
E) B and C

Question 35

Which coenzyme is required by glyceraldehyde 3-phosphate dehydrogenase in chloroplasts to convert 3-phosphoglycerate into glyceraldehyde 3-phosphate?

A) NADH
B) NADPH
C) NAD+
D) NADP+
E) thiamine pyrophosphate

Question 36

The energetic equivalent of ________ ATP molecule(s) is/are consumed in transporting CO2 to the chloroplasts of the bundle-sheath cells?

A) 1
B) 2
C) 3
D) 4
E) 6

Question 37

The C4 pathway is necessary in tropical plants because:

A) at high temperatures, the plants cannot maintain sufficient water levels within the cells.
B) tropical plants do not have proper day/light cycles to maintain the balance of CO2 necessary for carbohydrate storage.
C) at high temperatures, the oxygenase activity of rubisco is high.
D) All of the above.
E) None of the above.

Question 38

Why is the chemistry of the "dark reactions" referred to as a cycle and not a pathway?

Question 39

Which enzyme is cited as the most abundant enzyme in the biosphere? Why is this so?

Question 40

In the Calvin cycle, 3-phosphoglycerate is converted into which hexose phosphate?

A) glucose 1-phosphate
B) glucose 6-phosphate
C) fructose 6-phosphate
D) All of the above.
E) None of the above.

Question 41

How is rubisco activity controlled?

Question 42

How does light alter the fixation of CO2?

Question 43

Explain how the relationship of the mesophyll cell and the bundle-sheath cell help to regulate the Calvin cycle.

Question 44

Write the balanced reaction for the Calvin cycle.

Question 45

What is the energy requirement for the formation of hexose from CO2 in terms of ATP equivalents and NADPH?

Question 46

Describe the role of thioredoxin in regulating the Calvin cycle.

Question 47

What is the basic difference between C4 and C3 plants?

Question 48

Describe, in biochemical terms, how bread becomes stale.