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AQA BIOL2 Biology Unit 2 Exam - 26th May 2011 watch

  • View Poll Results: Are you resitting this unit?
    YES!
    28.62%
    NO!
    71.38%

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    (Original post by cobra2k10)
    hey, i hope everyones revision is going well!!! just revise hard and practise the how science work question aswell! if anyone needs the jan 2011 paper, PM me with your email address so i cant send it to you asap! i also have some revision notes available which are very useful,

    http://www.studentcreche.co.uk/resou...isionnotes.pdf

    http://www.studentcreche.co.uk/resources/biol2.pdf

    That second document is brilliant, shame I found it so late. Thanks!
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    From these exams I've decided I don't want to do medicine at university, if there's going to be this constant, incrementally greater, pressure.
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    (Original post by swiftylol)
    Someone explain founder effect and genetic bottleneck please, its like the thing i dont understand the most or at all even.
    Genetic bottleneck is when an event occurs that results in a reduction in the population. Could be a natural disaster. Because of the reduced population, there are fewer allelles so more people are genetically similar. Their allelles go into the gene pool too and new allelles are not introduced so there is low genetic variety. I think it get's its name because a bottle is larger at the bottom then becomes small at the neck of the bottle.

    Founder effect is an example of genetic bottleneck. Eg Amish people. They colonise an area. No new allelles are introduced. Reduced genetic variety.
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    (Original post by Nugard123)
    The trachea is lined with Chitin which is impermeable to gases. I think you covered everything else!
    Thanks, ok I get it now because originally in the NT book it said as the answer to a summary question that for gas exchange they have to have a thin permeable surface (which i think would be the spiracles?) and the Chitin is just for the trachea like you said.
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    I got 100 ums in Jan for this hoping for a repeat tomorrow!
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    Anyone else going to revise well into the night ? Only know about 2/3 of the unit
    Going to be a loooong nite!
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    Can someone explain to me what root pressure is?

    Much appreciated.
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    (Original post by Kishanpatel)
    What is most likely to come up as the six mark question and could some1 please give me a quick run-down of apoplastic and symplastic pathways as well as tissue fluid.

    Thanks
    *The 6 mark question could be on anything, unfortunately. If it isn't likely to come up if its been used before, then it probably wont be what lowers genetic diversity (june 2010, last question), features of arteries (january 2011).

    *The Apoplast is the pathway that moves water to the xylem, from the roots, through the cell walls of the plant cells. Once the water reaches the endodermis, the cell wall has a casparian strip. This strip is insoluble, so water can't pass through. This forces water to travel through the living part of the cell (as water can move through the apoplast pathway even when the plant is dead).
    *The Symplast pathway involves the water moving through the cytoplasms of the adjacent cells. This happens through the plasmodesmata (the small gaps in the cell wall, that join the cytoplasms of the adjacent cells). The water moves via osmosis, as solutes are dissolved in the cell, creating a water potential gradient. This pathway is not blocked in any way, unlike the apoplast pathway.
    *Tissue fluid is the fluid surrounding cells in your tissues. Its used as the cells main source of water an nutrients, including oxygen. Ultrafiltration is the movement of fluid from the blood into the tissue fluid, and some is drawn back into the blood by osmosis. Any excess can be drained by the lymphatic system. Lymph is the fluid inside the lymphatic system-its like tissue fluid but has more fat based substances, as fat is absorbed into the lymph during digestion. If lymph vessels block or cannot remove excess fluid, the tissue fluid accumulates-causing oedema, which is mainly visible as swelling.

    Hope this helps.

    (Original post by Master.K)
    What is the definition of a taxonomy?
    "A group of organisms that share similiar features" is the definition for a taxon, which is close. It should be the process of grouping organisms based on their characteristics, according to my textbook.

    (Original post by Kaylaleigh)
    I've done penty of past papers, and true I am getting about 60-70%, but just thought that seemed a little too low
    It may seem low, but i found the UMS converter for the aqa papers-getting 70/85 counts as full UMS marks (140/140), and its usually 52-60 that is the grade boundary for an A, which is the 60-70% you keep getting.
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    (Original post by CrispDust)
    Anyone else going to revise well into the night ? Only know about 2/3 of the unit
    Going to be a loooong nite!
    same here only half way through revision guide glad exam is in afternoon
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    (Original post by Patchey1000)
    I got 100 ums in Jan for this hoping for a repeat tomorrow!
    Why are you repeating it then? :confused:
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    (Original post by Unbiased Opinion)
    Nope, I would write this:

    sunlight causes evap from mesophyll (i think??)
    which puts xylem under tension.
    water forms continuous column because of its cohesive properties. these properties arise from the H bonds of water molecules.
    water molecules stick to dead xylem because of their adhesive properties.
    as water evaporates, the column is pulled up.

    Not sure if it's right though.
    OMG I actually understand this now lol, thank you!
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    If its not going to be about arteries and genetic diversity what else could they ask the 6 marker about?
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    (Original post by BeejTheone)
    If its not going to be about arteries and genetic diversity what else could they ask the 6 marker about?
    Gas exchange in fish/insects
    Tissue fluid
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    (Original post by Jim Lee)
    *The 6 mark question could be on anything, unfortunately. If it isn't likely to come up if its been used before, then it probably wont be what lowers genetic diversity (june 2010, last question), features of arteries (january 2011).

    *The Apoplast is the pathway that moves water to the xylem, from the roots, through the cell walls of the plant cells. Once the water reaches the endodermis, the cell wall has a casparian strip. This strip is insoluble, so water can't pass through. This forces water to travel through the living part of the cell (as water can move through the apoplast pathway even when the plant is dead).
    *The Symplast pathway involves the water moving through the cytoplasms of the adjacent cells. This happens through the plasmodesmata (the small gaps in the cell wall, that join the cytoplasms of the adjacent cells). The water moves via osmosis, as solutes are dissolved in the cell, creating a water potential gradient. This pathway is not blocked in any way, unlike the apoplast pathway.
    *Tissue fluid is the fluid surrounding cells in your tissues. Its used as the cells main source of water an nutrients, including oxygen. Ultrafiltration is the movement of fluid from the blood into the tissue fluid, and some is drawn back into the blood by osmosis. Any excess can be drained by the lymphatic system. Lymph is the fluid inside the lymphatic system-its like tissue fluid but has more fat based substances, as fat is absorbed into the lymph during digestion. If lymph vessels block or cannot remove excess fluid, the tissue fluid accumulates-causing oedema, which is mainly visible as swelling.

    Hope this helps.
    thank you!!

    also does any1 have any tips for the exam...?
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    (Original post by BeejTheone)
    If its not going to be about arteries and genetic diversity what else could they ask the 6 marker about?
    Could still be about arteries or genetic diversity, but if they did it in the last 2 exams, they might not risk doing it again. I'm thinking it could be on:
    *Mitosis
    *Gaseous exchange e.g. in fish and insects
    *Adaptions by xerophytes to dry conditions
    *Antibiotic resistance
    *Oxygen dissociation

    I could be wrong. And they might decide not to do a 6 mark question (doubt it)-it could be made longer, or they could just ask more 4 or 5 mark questions. Will find out tomorrow...
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    (Original post by BeejTheone)
    If its not going to be about arteries and genetic diversity what else could they ask the 6 marker about?
    Tissue fluid and blood plasma.
    DNA hybridisation.
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    I HOPE TO GOD tissue fluid doesn't come up. It's so annoying because even if you know all the content, the exam still screws you over!
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    (Original post by ScienceGeek3)
    Gas exchange in fish/insects
    Tissue fluid

    (Original post by Jim Lee)
    Could still be about arteries or genetic diversity, but if they did it in the last 2 exams, they might not risk doing it again. I'm thinking it could be on:
    *Mitosis
    *Gaseous exchange e.g. in fish and insects
    *Adaptions by xerophytes to dry conditions
    *Antibiotic resistance
    *Oxygen dissociation

    I could be wrong. And they might decide not to do a 6 mark question (doubt it)-it could be made longer, or they could just ask more 4 or 5 mark questions. Will find out tomorrow...

    (Original post by Limitless)
    Tissue fluid and blood plasma.
    DNA hybridisation.
    Cheers people, I hope its on gills
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    (Original post by Kishanpatel)
    thank you!!

    also does any1 have any tips for the exam...?
    When it says explain. EXPLAIN!
    When it says describe. DESCRIBE!
    When it says use the data. USE THE DATA!
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    (Original post by Sighrawr)
    I HOPE TO GOD tissue fluid doesn't come up. It's so annoying because even if you know all the content, the exam still screws you over!
    I'm thinking the same.
 
 
 
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