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AQA Biology Unit 4 January 2011

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    (Original post by M.A.)
    can anybody help with this:



    (c) In a population, 168 had red wings (dominant) and 32 had black wings (recessive). Showing your working in each case, calculate the frequency of:
    (i) the r allele;


    (ii) the R allele.


    answers are 0.4 and 0.6 but i got 0.16 for i).......


    never mind - i realised i've worked out rr, so need to square root for r. duh =)
    It's about the equation based around the Hardy-Weinberg Principle; p^2+2pq+q^2
    The value 168 here equals p^2+2pq as it's the phenotype caused by the dominant allele and 32 equals q^2. They're asking you for the r allele frequency, not the percentage phenotype in the population which shows r.
    So you've done the first part to the calculation, where you figure out the percentage of r phenotypes in the population, but you need to square root it to find the percentage of r alleles in the population, getting you 25% frequency.
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    I dont know if you guys can help me because I'm doing the OCR paper but it is A2 biology, i just couldnt find a thread for it. Do you know what it means when it says - 'you can measure the rate of photosynthesis experimentally by measuring the rate of increase in dry mass of the plant'. Thanks in advance!
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    (Original post by M.A.)
    can anybody help with this:



    (c) In a population, 168 had red wings (dominant) and 32 had black wings (recessive). Showing your working in each case, calculate the frequency of:
    (i) the r allele;


    (ii) the R allele.


    answers are 0.4 and 0.6 but i got 0.16 for i).......


    never mind - i realised i've worked out rr, so need to square root for r. duh =)
    It's about the equation based around the Hardy-Weinberg Principle; p^2+2pq+q^2
    The value 168 here equals p^2+2pq as it's the phenotype caused by the dominant allele and 32 equals q^2. They're asking you for the r allele frequency, not the percentage phenotype in the population which shows r.
    So you've done the first part to the calculation, where you figure out the percentage of r phenotypes in the population, but you need to square root it to find the percentage of r alleles in the population, getting you 25% frequency.
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    (Original post by Sapphire54)
    I dont know if you guys can help me because I'm doing the OCR paper but it is A2 biology, i just couldnt find a thread for it. Do you know what it means when it says - 'you can measure the rate of photosynthesis experimentally by measuring the rate of increase in dry mass of the plant'. Thanks in advance!
    i think the dry mass (biomass) of the plant will increase as the rate of photosynthesis increases. This is because as more photosynthesis occurs, more carbohydrates (glucose) are produced, if you refer to the photosynthesis equation. So if these are more carbohydrates the biomass will be greater. for AQA we have to know about the uptake of oxygen to measure the photosynthetic rate so i'm not sure if what i said earlier was 100% correct.
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    (Original post by -Iffy-)
    i think the dry mass (biomass) of the plant will increase as the rate of photosynthesis increases. This is because as more photosynthesis occurs, more carbohydrates (glucose) are produced, if you refer to the photosynthesis equation. So if these are more carbohydrates the biomass will be greater. for AQA we have to know about the uptake of oxygen to measure the photosynthetic rate so i'm not sure if what i said earlier was 100% correct.
    Thank you!
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    I'm doing this!! Really not looking forward to it, and I've not done half as much revision as I probably should have due to resits! I've been doing questions all day, reading and re-reading the chapters in the book. I really want to do well out of this exam!
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    (Original post by Sapphire54)
    Thank you!
    Your welcome. When's your exam? Good luck for it
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    (Original post by -Iffy-)
    Your welcome. When's your exam? Good luck for it
    Tommorow too. Thank you! Good luck to you too, hope it goes well
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    i know the theory inside out.
    but jesus them HSW questions, i can NEVER answer them.
    fat good all that revision's going to do if i cant even answer the bloody questions.
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    heyy !!

    I'm stuck on this extracellular digestion business that micro-organisms do. Do all of them do the same thing ?? So do the saprobiotic micro-organisms do extracellular digestion in eutrophication too ??
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    Extracellular digestion literally involves the saprobiotic microorganisms secreting enzymes onto the dead organic matter. Process of enzymes and substrates and break down is litterally that learnt in Biol1. Basically, in the carbon cycle the saprobiotic's will produce co2 when they respire the products of digestion whilst in the nitrogen cycle they will produce NH3 gas instead of CO2. In eutrophication there is not normally any sapribiotic microorganisms invloved is there?
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    (Original post by GP1993)
    Extracellular digestion literally involves the saprobiotic microorganisms secreting enzymes onto the dead organic matter. Process of enzymes and substrates and break down is litterally that learnt in Biol1. Basically, in the carbon cycle the saprobiotic's will produce co2 when they respire the products of digestion whilst in the nitrogen cycle they will produce NH3 gas instead of CO2. In eutrophication there is not normally any sapribiotic microorganisms invloved is there?
    When in the nitrogen cycle are there saprobiotic micro-organisms?
    Yeah in eutrophication there are saprobiotic mircroorganisms.
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    (Original post by Rickesh)
    When in the nitrogen cycle are there saprobiotic micro-organisms?
    Yeah in eutrophication there are saprobiotic mircroorganisms.
    It's when they decompose the dead matter, it's the ammonification process because they convert dead matter which is converted into ammonia gas and then ammonium ions (NH4+)

    Eutrophication

    1) Leeching occurs, nitrates enter a watercourse i.e . stream, lake.
    2) This increase in nitrates leads to an algal bloom of those algae on top of the water.
    3) Significantly less light is available to plants at the bottom of the water.
    4) Photosynthesis and hence glucose production cannot occur so plants begin to die.
    5) With fewer plants producing O2, there is an increased interspecific competition for 02
    6) Fish, plants and other aquatic organisms die.
    7) Anaerobically respiring bacteria decompose the dead matter, releasing co2 and acids. (Theres the decomposers, not sure if they are saprobiotic.)
    8) Water becomes a mucky soup.

    Thats how we were taught it
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    (Original post by GP1993)
    It's when they decompose the dead matter, it's the ammonification process because they convert dead matter which is converted into ammonia gas and then ammonium ions (NH4+)

    Eutrophication

    1) Leeching occurs, nitrates enter a watercourse i.e . stream, lake.
    2) This increase in nitrates leads to an algal bloom of those algae on top of the water.
    3) Significantly less light is available to plants at the bottom of the water.
    4) Photosynthesis and hence glucose production cannot occur so plants begin to die.
    5) With fewer plants producing O2, there is an increased interspecific competition for 02
    6) Fish, plants and other aquatic organisms die.
    7) Anaerobically respiring bacteria decompose the dead matter, releasing co2 and acids. (Theres the decomposers, not sure if they are saprobiotic.)
    8) Water becomes a mucky soup.

    Thats how we were taught it
    Oh yeah I see, so the saprobiotic miro-organisms release the enzyme and then breaks down the amino acids etc...that makes the ammonium ions.
    In the book it says saprobiotic micro-organisms...? Hmmm
    ahah mucky soup !
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    Any predictions anyone then? My biology teachers went on a AQA course and said the genetics questions will probably be on Genetic Crosses. And that the last big, usually 6/7 mark questions, will probs not be on photosynthesis as its come up quite a few times before, so either nitrogen ccycle or respiration are very big possibilities
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    Do you think we will need to know the specific amounts of energy yields at each stage e.g. amounts of rNAD and ATP produced? xx
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    i think there might be a last question on oxidative phosophorylation and how that synthesises atp???...just a guess.....:confused:
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    (Original post by animal*nature)
    Do you think we will need to know the specific amounts of energy yields at each stage e.g. amounts of rNAD and ATP produced? xx

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    Wow! Congratulations on the offers and interviewwwss!!
    I applied to liverpool, nottingham and bristol too, for medicine, and I've heard nothing from them yet
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    i am so unexplainably doomed to fail this exam :|
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    OOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMM MMMMMMMMMMMMMMMMMMMMMMMMMMMGGGGG GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGG!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!

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    Thought it was the hardest one yet.
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    How did everybody find it?

    To Mariiahgac thanks Ohhh really wow! that cool, I'm sure you will hear from them very soon! the waiting is horrible though isn't it hehe xxx

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