UNIT 4 TOPIC 1 PHOTOSYNTHESIS 3: THE LIGHTINDEPENDENT REACTIONS
Complete the notes sheets below. Where you see a blank
(…………………..), decide which word/phrase is most appropriate.
The light-independent reactions use the reducing
power of ………………… and the chemical energy
stored in ………………… (produced during the light………………… reactions). A series of reactions (the
………………… Cycle) takes place in the ………………… of a chloroplast. Carbon dioxide
from the ………………… is ………………… to carbohydrates in a series of ………………… controlled reactions.
1. CARBON FIXATION: Molecules of ………………… from the air combine with
(…..C)
ribulose
bisphosphate
(…………………).
The
………………… is now said
to be ………………… . The
highly
abundant
………………… ribulose bisphosphate carboxylase/oxygenase (…………………) is
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responsible for catalysing this step. (…..C) Glycerate-3-phosphate
(…………………) forms from a highly unstable …..C intermediate.
2. REDUCTION: The molecules of (…..C) GP
are phosphorylated using ATP, which
destabilises the molecule and provides
the
…………………
…………………
the
required
GP
to
to
(3C)
glyceraldehyde-3-phosphate
(…………………) using the reducing agent …………………. . The ………………… is
………………… back to NADP.
3. REGENERATION OF RuBP: Most of
the (…..C) GALP passes through a
series of steps to regenerate
(…..C) ………………… using some of
the ………………… produced during
the light-………………… reactions.
4. Some ………………… is converted into (…..C) glucose. It takes several turns of
the ………………… ………………… to produce 1 molecule of glucose.
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The entire Calvin Cycle:
PHOTOSYNTHESIS: A SUMMARY
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Photosynthesis Summary
Questions
Explain the steps in the light dependent reaction below
Photo-activation of Photosystem II
Photolysis of water
Electron transport
Cyclic phosphorylation
Non-cyclic phosphorylation
Photoactivation of Photosystem I
Reduction of NADP+
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Draw a diagram summarizing the light dependent reaction of photosynthesis
.
Explain phosphorylation in terms of chemiosmosis
Explain the roles of the following in the light independent reaction
RuBP
Reduction of glycerate-3-phosphate to GALP
NADPH + H+
ATP
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Regeneration of RuBP
Synthesis of carbohydrate
Describe two ways that photosynthesis can be measured directly
Describe one way that photosynthesis can be measured indirectly
Outline the effects of the following on the rate of photosynthesis and explain the concept
of limiting factors with reference to each
Temperature
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Light intensity
Carbon dioxide concentration
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