Biology option C.4 (photosynthesis)

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Chloroplast structure and function (light absorption)
Extensive system of thylakoids, large area ensures large light-absorbing capacity. Pigment molecules found in photosystems in thylakoid membrane carry out light absorption.
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Chloroplast structure and function (ATP production)
ATP production is done through photophosphorylation. This can happen is because the volume of fluid between the inner and outer membrane of the chloroplast is very small -> the proton gradient needed for photosynthesis is reached very quickly
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Chloroplast structure and function (The calvin cycle)
The stroma contains many enzymes needed for the calvin cycle. ATP and NADPH are produced in the thylakoids which in turn are distributed in the stroma, making them easily accessible.
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Photosynthesis (light dependent reaction) (steps 1+2)
1. Chlorophyll in photosystem 2 absorbs light, which causes photoactivation, which raises the energy level of an electron making it excited. 2.The electron is passed along a series of carries in the thylakoid membrane, giving up energy at each step.
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Photosynthesis (light dependent reaction) (step 3)
3. Energy from the electron is used to pump protons across the thylakoid membrane. The electrons lost in PS2 are replaced by photolysis of water.
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Photosynthesis (light dependent reaction) (step 4)
4. The accumulation of protons in the thylakoid space generates a high proton gradient,proton move through ATPsynthase by chemiosmois which generates ATP by coupling ADP and Pi. Production of ATP using electrons from PS2 is called non-cyclic photoph
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Photosynthesis (light dependent reaction) (step 5)
Electrons in PS1 are activated by light. They are recieved by ferredoxing (Fd) and are used to reduce NADP with an H+ ion using NADP reductase (enzyme). NADPH is carried to the light independent reactions.
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Photosynthesis (light independent reaction)
Occurs in the stroma of the chloroplast and is known as the calvin cycle.
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Photosynthesis (light independent reaction) (step 1)
Carbon fixation: CO2 enters the cholorplast by diffusion and combines with RuBP a carboxylation reaction. This reaction is catalysed by the enzyme rubisco. The 6 carbon product splits into 2 glycerate-3-phosphate molecules.
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Photosynthesis (light independent reaction) (step 2)
Glycerate 3-phosphate is converted to triose phosphate through reduction. 2NADPH is oxidised to 2NADP+. Energy from ATP molecules is required. ATP-> ADP
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Photosynthesis (light independent reaction) (step 3)
Some (1/6) of the triose phosphate are linked to form glucose phosphate. You need two triose phosphates for this. Starch is formed by condensation of many glucose phosphate molecules.
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Photosynthesis (light independent reaction) (step 4)
Most of the triose phosphates (5/6) are used to regenerate RuBP which requires ATP.
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Effect of temperature on rate of photosynthesis
The ling independent stages of photosynthesis were CO2 is fixed into organic compounds involves a series of enzyme controlled reactions. The enzymes work better when it is warmer until they get denatured and lose their shape and are unable to work.
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Effect of light intensity of rate of photosynthesis
A minimum amount of light is needed for photosynthesis to start. As the intensity increases, so does the rate of of photosynthesis. However, there comes a point where the chlorophyll molecules are saturated and cannot accept any more light.
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Effect of carbon dioxide concentration on rate of photosynthesis
A minimum amount of light is needed for photosynthesis to start. This is a substrate for an enzyme controlled reaction. As the CO2 level increases, so does the rate, but once all enzyme active sites are occupied, the reaction cannot go faster.
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Card 2

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Chloroplast structure and function (ATP production)

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ATP production is done through photophosphorylation. This can happen is because the volume of fluid between the inner and outer membrane of the chloroplast is very small -> the proton gradient needed for photosynthesis is reached very quickly

Card 3

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Chloroplast structure and function (The calvin cycle)

Back

Preview of the front of card 3

Card 4

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Photosynthesis (light dependent reaction) (steps 1+2)

Back

Preview of the front of card 4

Card 5

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Photosynthesis (light dependent reaction) (step 3)

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