Stages of the Calvin Cycle

Question 1

The energy and hydrogen are used during the light-independent reactions (known collectively as the Calvin cycle) to produce complex organic molecules, including (but not limited to) carbohydrates, such as:

Answer 1

Starch (for storage)
Sucrose (for translocation around the plant)
Cellulose (for making cell walls)

Question 2

This stage of photosynthesis does not, in itself, require energy from light (hence light-independent) and can therefore take place in light or darkness. However, as it requires inputs of ATP and reduced NADP from the light-dependent stage, the Calvin cycle cannot continue indefinitely in darkness, as

Answer 2

inputs will run out

Question 3

There are three main steps within the Calvin cycle:
Rubisco catalyses the fixation of

Answer 3

carbon dioxide by combination with a molecule of ribulose bisphosphate (RuBP), a 5C compound,

Question 4

carbon dioxide by combination with a molecule of ribulose bisphosphate (RuBP), a 5C compound, to

Answer 4

yield two molecules of glycerate 3-phosphate (GP), a 3C compound

Question 5

GP is reduced to…………… in a reaction involving

Answer 5

GP is reduced to triose phosphate (TP) in a reaction involving reduced NADP and ATP

Question 6

RuBP is regenerated from

Answer 6

TP in reactions that use ATP

Question 7

Glycerate 3-phosphate (GP) is not a carbohydrate but the next step in the Calvin cycle converts it into

Answer 7

one

Question 8

Energy from ATP and hydrogen from reduced NADP – both produced during the light-dependent stage of photosynthesis – are used to reduce glycerate 3-phosphate (GP) to a

Answer 8

phosphorylated three-carbon (3C) sugar known as triose phosphate (TP)

Question 9

One-sixth of the triose phosphate (TP) molecules are used to produce useful organic molecules needed by the plant:

Triose phosphates can condense to become hexose phosphates (6C), which can be used to produce starch, sucrose or cellulose

Triose phosphates can be converted to glycerol and glycerate 3-phosphates to fatty acids, which join to form lipids for cell membranes

Triose phosphates can be used in the production of amino acids for protein synthesis

Question 10

Regeneration of ribulose bisphosphate
Five-sixths of the triose phosphate (TP) molecules are used to

his process requires

Answer 10

regenerate ribulose bisphosphate

ATP