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AQA BIOL2 ~ 21 May 2012 ~ AS Biology

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    Oh yes. And plant and water stuff.
    Like the root pressure and cohesion tension thingy.
    What on EARTH are they people? Lol.
    I missed a whole 12 marks out of my exam through those questions. No idea what either are.
    And the text book is making my head spin, plus my teacher literally does us notes, but includes LOTS of things we dont need to know at all.
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    (Original post by britash)
    I'm exactly the same. Nowhere near finished my notes for unit 2.
    I'm just sort of hoping to blag it when i get into the exam room.
    I'm resitting unit 1 as well!! What did you get?

    Unit 2 to me is absoutely petrifying. I dont even know what horizontal/verticle transmission is even used in/for..
    I don't understand, like you, the tissue fluid, capillaries, arterioles, arterys stuff either.
    And the antibiotic resistance, like mutation :/
    Makes me so nervous! xoxo
    (same person, made a new account..)
    And same! Of course having sat the January 2012 exam already we have an advantage for Unit 1. But I just can't do Unit 2. Especially tissue fluid/ arterioles etc like you. And also plant cell structure. And the questions about diversity just confuse me.

    I got 76 UMS, what did you get?

    And horizontal and vertical transmission is alright. You just need to know that when DNA is passed from one species to another, the donor bacterial cell forms a conjugation tube between the two cells which it passes a replicated plasmid through (and the plasmid is broken to make it linear to pass through). The recipient cell receives the replicated plasmid and acquires new characteristics.

    And vertical gene transmission is just when genes eg.a gene which leads to the production of an enzyme that breaks down the bacteria, are passed down from one generation to the next.
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    (Original post by britash)
    Oh yes. And plant and water stuff.
    Like the root pressure and cohesion tension thingy.
    What on EARTH are they people? Lol.
    I missed a whole 12 marks out of my exam through those questions. No idea what either are.
    And the text book is making my head spin, plus my teacher literally does us notes, but includes LOTS of things we dont need to know at all.
    The Cohesion Tension Theory:


    • Water enters the xylem in the roots via osmosis.
    • Once in the xylem the water molecules form hydrogen bonds, forming a continuous column of water molecules up to the leaf.
    • Water is constantly lost by transpiration in the leaf.
    • When one water molecule is lost another is pulled along due to cohesion of water molecules.
    • This creates a tension or negative pressure.
    • Transpiration pull is the main cause of water movement and the upward flow of water is called transpiration steam.
    • Adhesion to the wall of the xylem vessels prevents the water falling backwards (not actually needed for specification).
    • The lignin in the xylem vessels prevents them from collapsing under tension.


    Root pressure:


    • Root pressure is created by the osmotic pressure of xylem sap, which is, in turn, created by dissolved minerals that have been actively transported into the xylem of the root by the endodermis.
    • This causes water to pass by osmosis into the xylem. The continuous inflow forces the sap up the xylem vessels creating an upward pressure.
    • Although root pressure plays a role in the transport of water in the xylem in some plants and in some seasons, it does not account for most water transport.
    • In extreme cases water can be pushed out of the ends of xylem vessels of the leaves. This is called guttation.

      Please feel free to critique what I've wrote, as that is how it is in my head and if it needs a reshuffle before the exam then I would appreciate being told by someone.
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    (Original post by thescientist17)
    (same person, made a new account..)
    And same! Of course having sat the January 2012 exam already we have an advantage for Unit 1. But I just can't do Unit 2. Especially tissue fluid/ arterioles etc like you. And also plant cell structure. And the questions about diversity just confuse me.

    I got 76 UMS, what did you get?

    And horizontal and vertical transmission is alright. You just need to know that when DNA is passed from one species to another, the donor bacterial cell forms a conjugation tube between the two cells which it passes a replicated plasmid through (and the plasmid is broken to make it linear to pass through). The recipient cell receives the replicated plasmid and acquires new characteristics.

    And vertical gene transmission is just when genes eg.a gene which leads to the production of an enzyme that breaks down the bacteria, are passed down from one generation to the next.
    I got 73 UMS. 3 marks off the A
    Yeah I agree, I'm much more comfortable with Biology 1 now we did January, sort of makes me feel as though I know what sort of questions will come up now
    Okay thanks for those descriptions.
    On past papers I just keep writing 'horizontal gene transmission of plasmids via conjugation'. Maybe that will get me a few marks? :/ x
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    (Original post by Tullia)
    The Cohesion Tension Theory:


    • Water enters the xylem in the roots via osmosis.
    • Once in the xylem the water molecules form hydrogen bonds, forming a continuous column of water molecules up to the leaf.
    • Water is constantly lost by transpiration in the leaf.
    • When one water molecule is lost another is pulled along due to cohesion of water molecules.
    • This creates a tension or negative pressure.
    • Transpiration pull is the main cause of water movement and the upward flow of water is called transpiration steam.
    • Adhesion to the wall of the xylem vessels prevents the water falling backwards (not actually needed for specification).
    • The lignin in the xylem vessels prevents them from collapsing under tension.


    Root pressure:


    • Root pressure is created by the osmotic pressure of xylem sap, which is, in turn, created by dissolved minerals that have been actively transported into the xylem of the root by the endodermis.
    • This causes water to pass by osmosis into the xylem. The continuous inflow forces the sap up the xylem vessels creating an upward pressure.
    • Although root pressure plays a role in the transport of water in the xylem in some plants and in some seasons, it does not account for most water transport.
    • In extreme cases water can be pushed out of the ends of xylem vessels of the leaves. This is called guttation.

      Please feel free to critique what I've wrote, as that is how it is in my head and if it needs a reshuffle before the exam then I would appreciate being told by someone.
    Wow this is detailed and clear.
    If I learnt these bullet points, do you think i'd be okay? ^^
    Or is there more to these two topics?
    I think learning what you wrote is do-able and it makes sense..! x Thanks x
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    (Original post by britash)
    I got 73 UMS. 3 marks off the A
    Yeah I agree, I'm much more comfortable with Biology 1 now we did January, sort of makes me feel as though I know what sort of questions will come up now
    Okay thanks for those descriptions.
    On past papers I just keep writing 'horizontal gene transmission of plasmids via conjugation'. Maybe that will get me a few marks? :/ x
    It was 80 UMS I think to get an A.. or did you mean raw marks?
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    'Costa Rica is a Central American country. It has a high level of species diversity.

    There are over 12000 species of plants in Costa Rica. Explain how this has resulted in a high species diversity of animals.


    The answer is
    - Greater variety/ different foods
    - More habitats/ niches

    Could someone please explain?

    I hate the exam questions. Some of them are very vague and they expect you to write exactly whats on the mark scheme for two marks. And some of them make it seem harder than it needs to be, like one question said 'why is it an advantage of cells lining the human intestine completing the cell cycle in a short time?' and the answer was 'to replicate cells more rapidly'. I thought it wanted an explanation as to why it was those cells in SPECIFIC that had a short cell cycle. I thought the answer was too obvious.

    Seriously dislike AQA, any exam board really.
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    (Original post by thescientist17)
    It was 80 UMS I think to get an A.. or did you mean raw marks?
    3 raw marks.
    Two of which I scribbled out on my paper and one mark got disqualified off me
    I was soo gutted x
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    (Original post by thescientist17)
    'Costa Rica is a Central American country. It has a high level of species diversity.

    There are over 12000 species of plants in Costa Rica. Explain how this has resulted in a high species diversity of animals.


    The answer is
    - Greater variety/ different foods
    - More habitats/ niches

    Could someone please explain?

    I hate the exam questions. Some of them are very vague and they expect you to write exactly whats on the mark scheme for two marks. And some of them make it seem harder than it needs to be, like one question said 'why is it an advantage of cells lining the human intestine completing the cell cycle in a short time?' and the answer was 'to replicate cells more rapidly'. I thought it wanted an explanation as to why it was those cells in SPECIFIC that had a short cell cycle. I thought the answer was too obvious.

    Seriously dislike AQA, any exam board really.
    This is exactly why I hate AQA. Everything is literally mark scheme questions.
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    (Original post by britash)
    3 raw marks.
    Two of which I scribbled out on my paper and one mark got disqualified off me
    I was soo gutted x
    Raw marks!? If that's the case I must've been one or two marks off an A I guess seeing as I got 76!
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    (Original post by britash)
    This is exactly why I hate AQA. Everything is literally mark scheme questions.
    Yes! And you could give a valid answer but get no marks because it's not what they want you to put. Does anyone know if you can still get a mark if it's a valid answer and the mark scheme is just being silly?

    And questions that have really obvious answers but they're too obvious so you don't put them down as you think they want more detail.

    And very very vague questions.

    My biology teacher always expresses anger at this system. He says that we're not properly being taught biology- just how to pass an exam, and to be honest, I feel the same. I think we need change!
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    (Original post by thescientist17)
    'Costa Rica is a Central American country. It has a high level of species diversity.

    There are over 12000 species of plants in Costa Rica. Explain how this has resulted in a high species diversity of animals.


    The answer is
    - Greater variety/ different foods
    - More habitats/ niches

    Could someone please explain?
    There are many species of plant, and so this offers a greater variety of food sources for different animal species to exist off. The different plant species offer different kinds of habitats, and so this allows different species of animal to exist within them.

    Niches isn't needed for our specification, but it is there because it used to be on the specification and possibly because resit candidates from A2 may come across it and use it.

    I can only see the trap in this question being a statement that more food is available and so more biodiversity exists, as this isn't accurate. It has to be a greater variety or to that effect.
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    (Original post by thescientist17)
    Raw marks!? If that's the case I must've been one or two marks off an A I guess seeing as I got 76!
    Yeah. You must have been 2 marks off
    This is why i'm questioning my re-sit to be honest.
    I can easily make up the three marks on my unit 2 when i revise everything *solidly* My isa mark isnt *too* bad either
    You'll get the A this time though. My guess is centrifugation will come up. Its not come up for *ages* x
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    (Original post by thescientist17)
    Yes! And you could give a valid answer but get no marks because it's not what they want you to put. Does anyone know if you can still get a mark if it's a valid answer and the mark scheme is just being silly?

    And questions that have really obvious answers but they're too obvious so you don't put them down as you think they want more detail.

    And very very vague questions.

    My biology teacher always expresses anger at this system. He says that we're not properly being taught biology- just how to pass an exam, and to be honest, I feel the same. I think we need change!
    Exactly. In January, on a question about enzymes I think.. I wrote a whole paragraph and didnt gain a single mark, even though everything I wrote was correct It's not fair at all.
    The marks should be given for the quality of the answer and the content. Not just the *exact* points that they state are necessary.
    My biology teacher is the same, he says you can know literally no biology and pass the exam x
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    Does anyone happen to have the jan 12 BIO2 paper and mark scheme?
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    (Original post by thescientist17)
    Yes! And you could give a valid answer but get no marks because it's not what they want you to put. Does anyone know if you can still get a mark if it's a valid answer and the mark scheme is just being silly?
    Answers not on the MS that are correct will be accepted. I've come across this many a time when going over AQA Physics MS, in which you get a marking point that some candidates across the country have put because they've done different exam boards in the past or do a lot of further reading and even though AQA don't have it in their specification it is accepted as it is correct.
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    (Original post by britash)
    Yeah. You must have been 2 marks off
    This is why i'm questioning my re-sit to be honest.
    I can easily make up the three marks on my unit 2 when i revise everything *solidly* My isa mark isnt *too* bad either
    You'll get the A this time though. My guess is centrifugation will come up. Its not come up for *ages* x
    But the final grade is in terms of UMS, not raw marks sadly, so it's not as simple as a case of making up a few marks. I would re sit if I were you! Though having said that this unit is worth almost 50%. So work harder for this one.

    And yes I'm hoping to get an A! I think I know everything now apart from needing to go over organelle functions, cholera, TB and immunity a bit more. Made silly mistakes in the Jan 2012 paper. I got three hours sleep the night before so hopefully if I get some sleep that'll make a difference.. But the heart/ lungs calculations really confuse me!
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    (Original post by thescientist17)
    Raw marks!? If that's the case I must've been one or two marks off an A I guess seeing as I got 76!
    You couldn't get 73 UMS, so I'm going to assume she meant 74 UMS and that would have meant she missed the A grade boundary by 3 marks. As you missed it by 2 marks.
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    (Original post by Kevalavek)
    Does anyone happen to have the jan 12 BIO2 paper and mark scheme?
    Yes!
    Attached Files
  1. File Type: pdf AQA-BIOL2-W-QP-JAN12.pdf (950.6 KB, 30 views)
  2. File Type: pdf AQA-BIOL2-W-MS-JAN12.pdf (233.9 KB, 31 views)
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    (Original post by britash)
    Wow this is detailed and clear.
    If I learnt these bullet points, do you think i'd be okay? ^^
    Or is there more to these two topics?
    I think learning what you wrote is do-able and it makes sense..! x Thanks x
    The bullet points I've given contain everything you'll need to get full marks on a question, so if you learn it by memory (but better, try to understand it) then you should be fine.

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