Download KEY - Photosynthesis Workshop: Putting it All Together

IB Biology Year 1 / IHS
KEY - Photosynthesis Workshop: Putting it All Together
Table 1. Summary of each stage of photosynthesis
One run of light
rxns with linear eflow
3 turns of the
Calvin Cycle
1.
Is light
absorbed?
Occur in
the dark?
Location in
plant cell
# of
H2O
used
# of O2
produced
# of
ATP
made
# of NADP
reduced
# of
CO2
used
# of
H2O
made
# of
ATP
used
# of NADPH
oxidized
Yes
No
1
½
1
1
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No
No!!
On thylakoid
membrane
of
chloroplast
In stroma of
chloroplast
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3
3
9
6
How many NADPH are required to produce one net molecule of triose phosphate? 6 NADPH per triose phosphate
2. How many Calvin Cycles are required to form one glucose molecule (C6H12O6)? 6 Calvin Cycles per glucose, since it takes two triose phosphates (each of
consists of 3 carbons) to make one six-carbon glucose.
which
3. Judging from # 1 & 2 and Table 1 above, how many light-dependent reactions are required to form one glucose with linear e- flow? 12 light reactions if
are operating with linear e- flow.
all of them
4.
How many ATP are required to produce one net triose phosphate molecule? 9 ATPs per triose phosphate One glucose? 18 ATPs per glucose
5.
Given your answers to #3 & 4, how are the rest of the ATP produced? The rest (18 – 12, or 6 more ATP needed) must be coming from cyclic e- flow.
6.
State at two different “fates” of the glucose made by photosynthesis.

Glucose can be respired in leaf cells’ mitochondria to generate ATP

Glucose can be used as a building block in polymers like cellulose or starch

Glucose can be used to make sucrose, which is the “traveling” form of sugar in a plant, and sent to feed the roots, which don’t do photosynthesis

Glucose can be used to make ALL the biomolecules plant cells need: amino acids (also requires N), fatty acids, nucleotides (also requires N), etc.
7.
Write the complete summary equation for photosynthesis:
12 H2O + 6 CO2 + light energy  6H2O + 6 O2 + C6H12O6 OR
6 H2O + 6 CO2 + light energy  6 O2 + C6H12O6