Calvin Cycle

Question 1

The cycle was discovered by ________ , ________ & ________ at the University of California, Berkeley

Answer 1

Melvin Calvin, Andrew Benson, and James Bassham

By using a radioactive isotope carbon-14 to trace the path of carbon atoms in carbon fixation, they performed experiments in unicellular algae Chlorella.

Question 2

Second stage of photosynthesis that is involved in the formation of sugar from CO2 using chemical energy stored

Answer 2

THE CALVIN CYCLE

light-independent reactions or “dark reactions” or reductive phosphate cycle.

Question 3

The Calvin Cycle needs to ‘spin’ (how many times) to make one molecule of G3P from three molecules of CO2

Answer 3

3

Question 4

What is a process of incorporating an inorganic carbon molecule, CO2, into an organic molecule?

Answer 4

CARBON FIXATION

Question 5

CO2 molecule is attached to a five-carbon sugar molecule named Ribulose-1,5- bisphosphate (RuBP) aided by an enzyme named ________?

Answer 5

Ribulose- 1, 5- bisphosphate carboxylase/oxygenase
(Rubisco)

Carbon Fixation

Question 6

Ribulose- 1, 5- bisphosphate must
first be phosphorylated by the enzyme

Answer 6

Phosphoribulose kinase

Carbon Fixation

Question 7

What is believed to be the most abundant protein in the chloroplast and maybe on Earth?

Answer 7

Ribulose- 1, 5- bisphosphate carboxylase/oxygenase
(Rubisco)

Question 8

The resulting product, a six-carbon sugar, is extremely unstable and immediately splits into half. The split forms two molecules of ____?

Answer 8

3-phosphoglycerate

(3-carbon), Carbon Fixation

Question 9

A phosphate group (from ATP) is then attached to each 3-phosphoglycerate by an enzyme _________ forming 1,3-Biphosphoglycerate.

Answer 9

Phosphoglycerate kinase (PGK)

Reduction

Question 10

Next, 1-3 Biphosphoglycerate is reduced by (1) to yield NADP+ and Glyceraldehyde-3-phosphate (G3P) with the aid of (2)

Answer 10

(1) NADPH, (2) Glyceraldehyde-3-phosphate dehydrogenase

Reduction

Question 11

For every six G3Ps produced by the Calvin Cycle, ____ are recycled to regenerate 3 molecules of RuBP

(NUMBER)

Answer 11

5

Question 12

Only _ G3P leaves the cycle to be
packaged for use by the cell.

(NUMBER)

Answer 12

1

Question 13

It will take _ molecules of G3P to make one molecule of glucose

Answer 13

2

Question 14

Glyceraldehyde-3-phosphate (G3P) is then reversibly converted to Dihydroxyacetone phosphate (DHAP) by ______ .

Answer 14

Triosephosphate Isomerase (TIM)

(1.4)

Question 15

________ condenses the two DHAP molecules to form Fructose- 1,6 bisphosphate (FBPase)

Answer 15

Aldolase

(1.5)

Question 16

CONVERTS

Fructose-1, 6-bisphosphate -> F6P (Fructose-6-Phosphate)

Answer 16

FBPase (Fructose 1, 6-Bisphosphatase)

(1.6)

Question 17

Dihydroxyacetone phosphate (DHAP) is converted in fructose-6-phosphate (F6P)
by ________?

CONVERTS DHAP in F6P

Answer 17

Aldolase and Fructose biphosphatase

(1.6.1) Converts DHAP in F6P

Question 18

Fructose 6-phosphate can then be converted into glucose via two enzymatic steps with the help of ________?

Answer 18

Phosphoglucoisomerase and Glucose-6-Phosphatase

(1.6.2) F6P -> C6H12O6

Question 19

F6P has two carbons removed by ________ giving Erythrose-4-phosphate (E4P)

Answer 19

Transketolase

(1.7)

Question 20

The two carbons on ________ are added to a G3P giving the Xylulose-5-Phosphate (X5P)

Answer 20

Transketolase

(1.7)

Question 21

Dihydroxyacetone (DHA) can also go on to condense with Erythrose-4-phosphate (E4P) to form Sedoheptulose-1, 7-biphosphate (SBP). This reaction is catalysed by ______.

Answer 21

Aldolase

(1.8)

Question 22

Sedoheptulose-1, 7-biphosphate (SBP). is then de-phosphorylated by ________ to yield Sedoheptulose-7-phosphate (S7P)

Answer 22

Sedoheptulose biphosphatase

(1.9)

Question 23

After several rearrangement reactions utilizing ________ & ________, Xylulose-5-phosphate (X5P) and Ribose-5-phosphate (R5P) are synthesized.

Answer 23

Transketolase and Transaldolase

(1.10)

Question 24

X5P is converted into Ribulose-5-phosphate (Ru5P) by______.

Answer 24

Phosphopentose epimerase

(1.11)

Question 25

R5P is isomerized by ________ to yield Ribulose-5-phosphate (Ru5P)

Answer 25

Phosphopentose isomerase

(1.12)

Question 26

Finally, ________ phosphorylates Ru5P, into RuBP, ribulose-1,5 bisphosphate

Answer 26

Phosphoribulose kinase

(1.13)

Question 27

Recipe for CARBOHYDRATE

or to make one molecule of G3P

Answer 27

(3) CO2
(9) ATP
(6) NADPH

Question 28

Recipe for GLUCOSE

Answer 28

(6) CO2
(18) ATP
(12) NADPH

Question 29

Plants in which the Calvin cycle uses CO2 directly from the air are called ________?

Answer 29

C3 Plants

Question 30

Examples of C3 Plants

Answer 30

soybeans, oats, wheat and rice

Question 31

________ is an adaptation that reduces water loss, but it also prevents CO2 from entering the leaf and O2 from leaving.

Answer 31

Closing stomata

Question 32

The entire process, starting with the fixation
of O2, is called ________?

Answer 32

photorespiration

Question 33

Advantages of photorespiration

Answer 33

1. Photorespiration can have photoprotective effects (preventing light-induced damaged to the molecules involved in photosynthesis)
2. Help maintain redox balance in cells
3. Support plant immune defences.

Question 34

________ have special adaptations that save water and also prevents photorespiration.

(moves CO2 molecules)

Answer 34

C4 plants

Question 35

An enzyme fixes carbon into a four-carbon (4-C) compound instead of 3-PGA.

Answer 35

Phosphoenolpyruvate carboxylase (PEP carboxylase)

Question 36

Examples of C4 Plants

Answer 36

Corn, sorghum, and sugar cane

Question 37

______ conserves water by opening its stomata and admitting CO2 only at night.

Answer 37

Crassulacean Acid Metabolism (CAM) Plants

Question 38

Examples of CAM Plants

Answer 38

Pineapples and Cacti