Photosynthesis

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  • Created by: Massu786
  • Created on: 29-11-17 18:33
What are the main adaptations of the leaf?
large surface area for light absorption, thin for short diffusion pathway, transparent cuticle to let light pass, numerous stomata for gas exchange, air spaces in mesophyll for rapid diffusion, xylem,phloem to transport water/sugars, many chloroplast
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describe the structure of the chloroplast
Grana- stack of thykaloids. thykaloids (contain chlorophyll)- site of light dependent reaction,integranal lamellae join up with thykaloids in adjacent grana ,stroma- site of light independent reaction, contains starch grains (stored carbohydrates)
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describe what happens in the light dependent reaction
light energy excites electrons, electrons pass down electron transfer chain in chloroplast membrane involves redox reactions, energy decreases at each level, ATP formed from ADP+pi, photolysis of water , NADP reduced by electrons/protons added to it
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describe the chemiosmotic theory that occurs in the light dependent reaction
protons pumped from stroma into thykaloid, energy to do this comes from photolysis, thykaloid now has higher conc of protons than stroma which causes protons to move down their conc gradient back into the stroma through ATP synthase chann
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describe the process of photolysis of water
water is split using light energy which produces protons electrons and oxygen
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why does the photolysis of water occur?
to replace the electrons that are lost during photoionisation (when light hits the chlorophyll and it looses electrons), Its also used to reduce NADP
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How are chloroplasts adapted for the light dependent reaction?
thykaloid membrane has a large SA for attachment of enzymes/electron carriers,proteins in grana hold chlorophyll in place for absorption of light, granal membranes contain ATP synthase needed to make ATP, contain DNA and ribosomes to make proteins
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What products from the light dependent reaction are needed for the light independent reaction and what are there functions?
reduced NADP - provides protons and electrons to convert GP to TP ATP- provides energy to convert GP into TP, provides phosphate for TP to regenerate RuBP
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describe what happens in the light independent reaction
RuBP combines with CO2 to form 2GP catalysed by enzyme rubisco, 2GP reduced to 2 molecules of TP by gaining electrons/H+ from reduced NADP and energy from ATP, for every 6TP made 5 TP used to regenerate RuBP, 1 TP used to make sugars
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How are chloroplasts adapted for the light independent reaction
stroma contains enzymes needed for LIR, stromal fluid surrounds grana so products of LDR can diffuse into stroma, contains DNA and ribsomes to make proteins for LIR
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what are the limiting factors of photosynthesis?
light intensity, carbon dioxide, temperature,
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What is the light compensation point for?
the particular level of light intensity which results in the rate of photosynthesis exactly matching the rate of respiration, the light intensity at which oxygen is being used in respiration as quickly as its being produced in photosynthesis
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describe why carbon dioxide can be a limiting factor
because carbon dioxide concentration affects enzyme activity in particular the enzyme that catalyses the combination of RUBP and CO2 in the light independent reaction, the optimum conc of co2 is 0.1% bur in the atmosphere theres only 0.04%
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describe why temperature can be a limiting factor
temperature affects rate of enzyme activity,if temp is too low enzymes may become inactive ,if temp is too high they may denature and stomata may also close to conserve water and this means co2 cant enter either so photosynthesis slows down
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Card 2

Front

describe the structure of the chloroplast

Back

Grana- stack of thykaloids. thykaloids (contain chlorophyll)- site of light dependent reaction,integranal lamellae join up with thykaloids in adjacent grana ,stroma- site of light independent reaction, contains starch grains (stored carbohydrates)

Card 3

Front

describe what happens in the light dependent reaction

Back

Preview of the front of card 3

Card 4

Front

describe the chemiosmotic theory that occurs in the light dependent reaction

Back

Preview of the front of card 4

Card 5

Front

describe the process of photolysis of water

Back

Preview of the front of card 5
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