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    (Original post by markioe)
    I got to know, i asked and they told me, obviously this was the pre-standardisation mark (like without grade boundaries)
    who did you ask? :confused:
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    Right, seriously need to finish revising for this exam.. so far, I've only got past the krebbs cycle :facepalm2:
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    The 3rd and final set of questions that I can offer you guys:

    Side 1:
    http://www.mediafire.com/i/?jxwvzujny3e

    Side 2:
    http://www.mediafire.com/i/?dnvwtdyozt4
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    (Original post by ajun001)
    hey guys wht book do you use which covers everything the best?? i have the large green edexcel textbook and the green cgp revision guide specific to edexcel...would you say revising the spec from those 2 books is sufficient???
    CGP dude, it's got no waffly ******** in it at all and it has all the information you need to get an A. That edexcel book is useless (for the exam).


    (Original post by Pedus)
    Right, seriously need to finish revising for this exam.. so far, I've only got past the krebbs cycle :facepalm2:
    I'm in a similar situation :/ Let's do it! :ahee:
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    Im starting to get scared now... So much to learn compared to other units let alone learning the synoptic.

    Do we need to know HOW auxin brings about cell elongation or just the fact the it does and how it responds to light.
    The HOW is at the bottom right of page 215 in the SNAB text book. For those who cba to find it it says;
    "By binding to the receptors on the plasma membranes in the zone of shoot elongation, auxins produce second messenger singal molecules that bring the changes in gene expression. Transriptions of genes coding for enzymes then result in metabolic changes. It is thought auzins bring an acidification of the cell wall by stimulation the activity of proton pumps that move H+ out of the cytoplasm. It is thought the low pH effects an enzyme in the cell walls causing bonds between cellulose microibirls to break, allowing the cell wall to expand. The increased pd across the membrane enhances uptake of ions into the cell which causes water uptake hense cell elongation."
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    I don't understand why oxygen is necessary for aerobic respiration, like what does it have to do with oxidation and NAD and that? it is just that it combines with hydrogen at the end of the electron transport chain to make water? if so, why is oxygen so vital for the entire process?

    Also, what are substrate level and oxidative phosphorylation? What is the difference? and when exactly does each occur during respiration? All I know is that oxidative phosphorylation is what happens when ATP is created via the electron transport chain, I don't know what it actually is if you get what I mean.

    I'd be really grateful if anyone could help me out at all, cheers
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    (Original post by _joshb_)
    I don't understand why oxygen is necessary for aerobic respiration, like what does it have to do with oxidation and NAD and that? it is just that it combines with hydrogen at the end of the electron transport chain to make water? if so, why is oxygen so vital for the entire process?

    Also, what are substrate level and oxidative phosphorylation? What is the difference? and when exactly does each occur during respiration? All I know is that oxidative phosphorylation is what happens when ATP is created via the electron transport chain, I don't know what it actually is if you get what I mean.

    I'd be really grateful if anyone could help me out at all, cheers
    same problem im facing right now...
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    (Original post by _joshb_)
    I don't understand why oxygen is necessary for aerobic respiration, like what does it have to do with oxidation and NAD and that? it is just that it combines with hydrogen at the end of the electron transport chain to make water? if so, why is oxygen so vital for the entire process?

    Also, what are substrate level and oxidative phosphorylation? What is the difference? and when exactly does each occur during respiration? All I know is that oxidative phosphorylation is what happens when ATP is created via the electron transport chain, I don't know what it actually is if you get what I mean.

    I'd be really grateful if anyone could help me out at all, cheers
    if oxygen isn't present then the electron transport chain stops because the electrrons and hydrogen ions have no where to go meaning that no NAD or FAD is reformed and therefore there is no FAD or NAD to be reduced during krebs or link reaction.

    substrate level phosphorylation occurs during glycolysis and krebs cycle. It is substrate level because the energy required to make the ATP comes from the substrates. oxidative phosphorylation occurs in the electron transport chain and is oxidative phosphorylation because redox reactions are occuring throughout the electron transport chain and oxygen is the final electron acceptor

    hope that helps, sorry i'm not the best at explaining things
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    Oxygen is needed for aerobic respiration because it acts as the final acceptor for the hydrogen produced, during glycolysis, the link reaction and the krebs cycle.If there was no oxygen, none of the hydrogen produced will be accepted.

    Substrate level phosphorylation is when ATP is produced from the substrates of the reaction, like during glycolysis when the intermediate 3 carbon compound is oxidised to form pyruvate, the phosphate( which was added to the beginning to the glucose to make it more reactive) is used in making the ATP. The glucose is at a higher energy level so some energy becomes avilable to form the ATP.

    Oxidative PHosphorylation is when hydrogens and electrons are removed from a substrate by carriers (NADFAD) and are passed along successively lower energy levels. THe energy released converts ADP to ATP.
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    (Original post by sidrah)
    Glad it helped
    hurry up with the topic 8 one then
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    hey guys how much syoptic r u revising. like r u going to relearn like cell division from unit 2 etc again....
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    (Original post by dunnoaboutme)
    hurry up with the topic 8 one then
    It takes time, I don't HAVE to do this, I'm putting them up to help people...
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    Substrate level phosphorylation is when ATP is made directly, rather than being made in the electron transport chain by chemiosmosis. It occurs in glycolysis and the krebs cycle.
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    (Original post by dunnoaboutme)
    hurry up with the topic 8 one then
    You can't be serious?! :lolwut:
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    Just finished on topic 8..
    Topic 8 is the first one, and I've also got topic 7 with the correction.
    My neurone drawings are awful, so the brain and eye were off google lol..
    Attached Images
  1. File Type: pdf Topic 7 and 8.pdf (525.6 KB, 186 views)
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    (Original post by sidrah)
    Just finished on topic 8..
    Topic 8 is the first one, and I've also got topic 7 with the correction.
    My neurone drawings are awful, so the brain and eye were off google lol..
    Thank you very much that's awesome Greatly appreciated! I've already given you rep but i'll give you more when I can haha.



    :five:
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    (Original post by Swaying Eel)
    Thank you very much that's awesome Greatly appreciated! I've already given you rep but i'll give you more when I can haha.



    :five:
    lol
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    (Original post by jimber)
    Give an account of the role of pigments in the detection of light by flowering plants and animals.
    (Allow three lined pages)
    (Total 10 marks)
    :eek3: :confused:
    (Original post by koop)
    ...
    Ok... basically photoreceptors in plants are known as phytochromes. There are 5 different types and each is made up of a protein part and a non-protein part. We are interested in the non-protein part as this is the part that absorbs light.

    The non-protein component exists in two forms:
    - Phytochrome red (absorbs red light, 660nm) which is inactive
    - Phytochrome far red (absorbs far red light, 730nm) which is active

    Let's call phytochrome red 'Pr' and phytochrome far red 'Pfr'.

    Phytochromes control germination, as you should know - plants fail to germinate in the dark.

    Absorption of red light converts Pr to Pfr. Pfr is the active phytochrome so the plant can germinate when exposed to red light.

    Absorption of far red light converts Pfr to Pr. Pr is inactive, so the plant fails to germinate when exposed to far red light.

    The effects of red light and far red light are reversible. Sunlight is mainly red light so the conversion of Pr to Pfr dominates and plants are able to grow as they have lots of Pfr, which is active. In the dark Pfr is slowly converted back to Pr, which is inactive, but this is done to enable the conversion of Pr to Pfr when red light is absorbed again in sunlight.

    The reason why some plants are classed as short-day plants is that they convert Pfr back to Pr slowly, whereas some plants, known as long-day plants, can convert Pfr back to Pr quickly, so they don't require as much darkness for the plant to be able to continue growing. This is why plants have different growing seasons - known as photoperiods.

    Hope this helps!
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    what tpe of synoptic stuff do you reckon theyll ask us?

    ive revised from the CGP book specific to edexcel and as for the pre-release ive gone through it and made notes....edexcel told our teachers we only had to understand the biology within the article...is that right?
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    (Original post by sidrah)
    Just finished on topic 8..
    Topic 8 is the first one, and I've also got topic 7 with the correction.
    My neurone drawings are awful, so the brain and eye were off google lol..
    at last.. can u do the article part now like give us notes on whats goin to come up
 
 
 
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