UNIT 4 TOPIC 1 PHOTOSYNTHESIS 3: THE LIGHT-INDEPENDENT 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 ………………… required to …………………

the GP 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+

Draw a diagram summarizing the light dependent reaction of photosynthesis

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.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

Regeneration of RuBP

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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

Light intensity

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Carbon dioxide concentration

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