KEY- Chapter 10 Study ?’s (part 3): The Calvin Cycle / Mechanisms of C-Fixation
1) REVIEW: Which 2 products of the light reactions are necessary for the running of the Calvin cycle? On
which side of the thylakoid membrane are these 2 substances produced?
ATP & NADPH; produced on the stroma side
2) Complete this passage by filling in the blanks: “Carbon enters the Calvin cycle in the form of
CO2
and leaves in the form of sugar . The cycle spends ATP as an energy source and consumes NADPH
as reducing power for adding high-energy electrons to make the sugar.”
3) What carbohydrate is produced directly from the Calvin cycle? How many times must the cycle take
place to synthesize one molecule of this sugar?
G3P; 3 times
4) What is rubisco? What is its function?
rubisco is the enzyme that catalyzes the reaction between CO2 and RuBP; this reaction fixes the Carbon
into an organic molecule
5) Create a chart in which you summarize the 3 phases of the Calvin cycle with respect to the “inputs” and
“outputs”, including any energy molecules consumed.
PHASE
1) Carbon fixation
INPUTS
3 CO2, 3 RuBP,
2) Reduction
6 3-Carbon low energy molecules
(GP); 6 ATP; 6 NADPH
5 G3P; 3 ATP
3) regenerate RuBP
OUTPUTS
6 3-Carbon low energy
molecules
6 G3P (high energy!!); 6 ADP; 6
NADP+
3 RuBP; 3 ADP
6) Compare the use of ATP during the Calvin cycle with the use of NADPH. How is this difference related
to the light reactions?
more ATP is used in the Calvin Cycle than NADPH; since more ATP is used, the Light Reactions will
produce more ATP through cyclic electron flow to make up the difference
7) What happens to the G3P produced by the Calvin cycle?
it is the starting material for metabolic pathways that synthesize other organic compounds (ex: glucose
and other carbohydrates)