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BIOL4 Biology Unit 4 Exam - 13th June 2011 watch

  • View Poll Results: Are you resitting this unit?
    YES!
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    NO!
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    Fertilizer for farmers and also addition of manure can cause eutrophication by breaking down the manure.
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    (Original post by andrewcreed)
    And it is directional selection. Only one extreme is being acted against (the one which does not produce the enzyme) and therefore must be directional.
    THIs. Man this is exactly what I was thinking - because stabilising is when both extremes are eliminated.
    But people who put down stabilising selection had good justifications as well :confused:
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    (Original post by Jing_jing)
    Yeah it does, anaerobic repiration is basically glycolysis and then the conversion of pyruvate into either ethanol or lactate. If it didn't produce ATP then there would be no point to it.
    Read my above post. Isn't anaerobic respiration just:
    pyruvate+reduced NAD ----> lactate + NAD
    In my mind, glycolysis is separate, and thats the way they make it out to be in the NT book. Trick question...
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    Sometimes they may only be one extreme hopefully. Has there ever been a question on the mark scheme where justification of an answer provides marks and either can be right or wrong?
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    Read my above post. Isn't anaerobic respiration just:
    pyruvate+reduced NAD ----> lactate + NAD
    In my mind, glycolysis is separate, and thats the way they make it out to be in the NT book. Trick question...
    But the reduced NAD becomes NAD to continue glycolysis and produce ATP.
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    (Original post by tehsponge)
    Read my above post. Isn't anaerobic respiration just:
    pyruvate+reduced NAD ----> lactate + NAD
    In my mind, glycolysis is separate, and thats the way they make it out to be in the NT book. Trick question...
    Nope, anaerobic respiration includes glycolysis, that's the way we've been taught it anyhow.
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    (Original post by Jing_jing)
    Nope, anaerobic respiration includes glycolysis, that's the way we've been taught it anyhow.
    Well thats another 2 ****ing marks down.
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    Hey guys I was wondering if anyone had managed to sneak away a paper that they had uploaded or the questions? and also if there is anything like an unoffical markscheme anywhere?
    Sorrry for asking, it's just my internet is being SOO slow so I can't really look through the pages!
    Soooo, how did yaaa all find it?! I thought it was okay... although completely ran out of time so left 17 marks unanswered Ouch! Do you think I could still get a B with what I did answer?
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    (Original post by FatalError)
    Sometimes they may only be one extreme hopefully. Has there ever been a question on the mark scheme where justification of an answer provides marks and either can be right or wrong?
    Yeah it has happened before, usually when mistake has been made when writing the paper and more than one answer can be justified.

    Wouldn't be surprised to see it for the very first question today since you can argue that photosynthesis produces ATP and that it doesn't. Because ATP is produced but used in the following reaction so results in no net gain of ATP following photosynthesis. I personally didn't tick it because the question made me think it meant final products but they should mark it correct either way really.
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    (Original post by tehsponge)
    But anaerobic respiration doesn't produce ATP...it lets glycolysis continue which produces ATP doesn't it?

    Yeah, anaerobic is glycolysis which produces 4 ATP but net gain of 2. The whole point of respiration is to produce ATP, e.g. for sprints, we need short bursts of energy, and lactic acid builds up due to anaerobic respiration!
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    i think its stabilising selection because the recessive alleles are in the minority and stabilising favours phenotypes close to the mean (i.e not recessive) therefore recessive ones die!
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    (Original post by fsaeed20)
    what did people get for the two advantages for using the methane tank thing.

    i said
    1. methane can be sold or used as it is a fule generating revenue
    2. fertiliser can be used or sold.

    1 - Doesn't decrease oxygen concentration in the ponds, as no waste for aerobic bacteria to feed on

    2 - Can be easily removed from tank, and placed whereever. Whereas, in pond, we would have to go to bottom and take out the nutrients - expensive and laborious??
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    This thread is making me sad :cry2: Can the OP make a poll please so we can find out how everyone found it so that we don't have to go through 50 pages...
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    (Original post by INeedToRevise)
    This thread is making me sad :cry2:
    Same. I felt happy when I finished the exam. Now I feel like ****. And I can't stop looking at this thread...
    I needed an A as well lol.
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    Yeah it has happened before, usually when mistake has been made when writing the paper and more than one answer can be justified.

    Wouldn't be surprised to see it for the very first question today since you can argue that photosynthesis produces ATP and that it doesn't. Because ATP is produced but used in the following reaction so results in no net gain of ATP following photosynthesis. I personally didn't tick it because the question made me think it meant final products but they should mark it correct either way really.
    I ticked the correct boxes and Xd the wrong ones, do you think they'll let me off?

    Glycolysis does produce net gain of two ATP as 2 ATP hydrolysed to lower energy levels and 2 ATP produced from each pyruvate by substrate level phosphorylation.
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    (Original post by tehsponge)
    Same. I felt happy when I finished the exam. Now I feel like ****. And I can't stop looking at this thread...
    I needed an A as well lol.
    Omd. I'm exactly the same. The thing is, some of the questions I didn't even doubt my answer to. Like the selection one, and then you come on here and you find out loads of people say its directional. I think the grade boundaries are going to be high as well.
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    (Original post by tehsponge)
    Read my above post. Isn't anaerobic respiration just:
    pyruvate+reduced NAD ----> lactate + NAD
    In my mind, glycolysis is separate, and thats the way they make it out to be in the NT book. Trick question...
    Where does this pyruvate come from? It isnt just randomnly from somewhere in the body! So glycolysis is required to convert glucose into pyruvate. They are not separate. Glycolysis is the first step of anaerobic respiration...
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    (Original post by FatalError)
    I ticked the correct boxes and Xd the wrong ones, do you think they'll let me off?

    Glycolysis does produce net gain of two ATP as 2 ATP hydrolysed to lower energy levels and 2 ATP produced from each pyruvate by substrate level phosphorylation.
    Yeah you'll be fine, I'd be shocked if they marked that wrong. You're clearly still showing the correct knowledge so they should mark it right.
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    (Original post by INeedToRevise)
    Omd. I'm exactly the same. The thing is, some of the questions I didn't even doubt my answer to. Like the selection one, and then you come on here and you find out loads of people say its directional. I think the grade boundaries are going to be high as well.
    I know. I feel awful right now. I don't want to go to my Insurance choice, and the fees rise next year... Looks like I'll be going through Clearing.
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    What did everyone put for the very last question (6 marks) ? I wrote a whole essay on the light dependent and independent reaction and completely forgot that it was about the Calvin cycle. Do you think I will get any marks for that question? Generally speaking, I thought it was easier than the January paper, I only need/want a C so hopefully it will be about 36 marks for a C.
 
 
 
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