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BIOL4 Biology Unit 4 Exam - 13th June 2011 watch

  • View Poll Results: Are you resitting this unit?
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    can some1 please list out the main concepts of chap 5 (energy and ecosysyems)?

    many thanks, like the key points :P
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    (Original post by jonnyboy1993)
    It's about realising they are testing your knowledge of aerobic and anaerobic respiration. Before being moved the apple is respiring almost entirely aerobically. During this, for every glucose molecule, 6 molecules of CO2 are produced. But equally a lot of ATP molecules are produced (36, 38 or 40 depending on how you work out your net production, assuming full efficiency, which is unrealistic, but not really to be worried about in this question). What matter is that we get around 6 ATP per CO2 molecule produced. After being moved to the nitrogen atmosphere, so no oxygen is present, the apple respires anaerobically so we get 2 CO2 and a net production of 2 ATP per glucose. This means we only get 1 ATP per CO2. Now if we assume the apple is using up ATP in metabolic processes etc at the same rate in both atmospheres then for every 6 CO2 molecules produced in anaerobic conditions only one is produced in aerobic conditions. As a result the rate of CO2 production is higher in the nitrogen atmosphere, despite the fact this might intuitively appear wrong.
    this may sound stupid so sorry lol - but during which process is CO2 produced during anaerobic respiration?? Is it the bacteria (yeast) that convert pyruvate into ethanol for plants? do they respire it, but if so how?
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    (Original post by SK-mar)
    this may sound stupid so sorry lol - but during which process is CO2 produced during anaerobic respiration?? Is it the bacteria (yeast) that convert pyruvate into ethanol for plants? do they respire it, but if so how?
    during conversion of pyruvate to ethonol, CO2 is produced.
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    I am so ****ing worried about tomorrow. I know all the content but the questions are going to screw me over.
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    (Original post by tehsponge)
    I am so ****ing worried about tomorrow. I know all the content but the questions are going to screw me over.
    dont spend ages on content do as much practise..talking from experience lol ..
    in jan i spent ages revising content .. gt me an E
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    what is the role of cytokines??
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    (Original post by GdotNizzle)
    what is the role of cytokines??
    Cytokines are released from t'helper cells to alert t'killer cells to kill infected cells and cause b -cells to multiply and differentiate into plasma cells and so on....
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    (Original post by ziad aka zoohands)
    Cytokines are released from t'helper cells to alert t'killer cells to kill infected cells and cause b -cells to multiply and differentiate into plasma cells and so on....
    wat the hell is this haha? edexcel?
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    (Original post by ziad aka zoohands)
    Cytokines are released from t'helper cells to alert t'killer cells to kill infected cells and cause b -cells to multiply and differentiate into plasma cells and so on....
    Cheers

    and yes it is edexcel
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    question for you :

    It is about energy transfer from sunlight to a bullock which feeds on grass....

    amount of energy in sunlight = 1046700 kj m^-2 per year.
    of this the grass is 13.1% efficient.
    of this the bullock uses 4.1% of its energy for new tissue.

    the energy stored in the new tissue of the bullock each year is 125 kj m^-2 ....

    calculate the amount of energy trapped each year by each square metre of grass.... show your working. (2 marks) ...
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    I just realised the exam is tomorrow...
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    AAAAH TOMORROW. im crapping myself!

    Cause i cant be bothered to skim through this whole thread again... can someoe please tell me the general ideas/predictions for this exam!?!?

    AAAH solid day of revising today. -.-
    Are you's going to revise for a few hours tomorrow morning?
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    Guys, could someone please help me on this question in the Nelson Thornes textbook. I don't understand it at all and it has come up before on previous papers. Its page 57, and the application box titled 'Sequencing the chain'.
    +rep. Thanks
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    (Original post by SK-mar)
    question for you :

    It is about energy transfer from sunlight to a bullock which feeds on grass....

    amount of energy in sunlight = 1046700 kj m^-2 per year.
    of this the grass is 13.1% efficient.
    of this the bullock uses 4.1% of its energy for new tissue.

    the energy stored in the new tissue of the bullock each year is 125 kj m^-2 ....

    calculate the amount of energy trapped each year by each square metre of grass.... show your working. (2 marks) ...
    Is the answer: Energy stored by grass is 3049 kJm-2
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    I found this excellent note completely describing everything that could possibly come in unit 4; http://www.heckgrammar.co.uk/getObje...it_4_Notes.pdf

    Why the neg?
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    (Original post by INeedToRevise)
    Guys, could someone please help me on this question in the Nelson Thornes textbook. I don't understand it at all and it has come up before on previous papers. Its page 57, and the application box titled 'Sequencing the chain'.
    +rep. Thanks
    Hi i had a problem with this before my teacher went through it well basically yuou have to work out where the inhibitor is working because the electron carriers after cannot be reduced so will stay oxidised as the electrons cannot be passed on.
    Therefore C is first as it is reduced with all three inhibitors, then A and so on?
    does that help?
    sorry if im a bit complex with my explaining... if you draw the chain out and mark on where each inhibitor is acting it might help better.
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    (Original post by GdotNizzle)
    Is the answer: Energy stored by grass is 3049 kJm-2
    no... i thought this at first. did you just do 125/4.1 x 100 = 3049 ..... cos thats what i did.

    apparently the answer is 23,275... but i don't know how you get there? apparently the markscheme uses the equationd 125/4.1 and 125/13.1 ???
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    (Original post by tweety9)
    Hi i had a problem with this before my teacher went through it well basically yuou have to work out where the inhibitor is working because the electron carriers after cannot be reduced so will stay oxidised as the electrons cannot be passed on.
    Therefore C is first as it is reduced with all three inhibitors, then A and so on?
    does that help?
    sorry if im a bit complex with my explaining... if you draw the chain out and mark on where each inhibitor is acting it might help better.
    Thanks for helping. I'm still a little confused. How do you work out where the inhibitor is working?
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    Can someone tell me where I could find a 6 marker on a quadrat question? :confused:
    My friend saw it somewhere, but he can't remember where? :/

    Thanks.
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    (Original post by SK-mar)
    no... i thought this at first. did you just do 125/4.1 x 100 = 3049 ..... cos thats what i did.

    apparently the answer is 23,275... but i don't know how you get there? apparently the markscheme uses the equationd 125/4.1 and 125/13.1 ???
    Well through trial and error method, i found:

    let x = 125/4.1,

    ((x*100)/13.1)*100= 23,273 but thats just a random answer

    ask your teachers tomoz
 
 
 
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