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AQA BIOL1 Biology Unit 1 Exam - 16th May 2011 Watch

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    (Original post by liviaaa)
    Starch is a carbohydrate...
    Yeah i realised a tad after replying xD
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    (Original post by Tericon)
    Excuse the stupidity, but I still don't understand that, ok, distance is 20....how did you work out rate of blood flow?
    Convert all measurements into Um and u get 200um s-1 for blood flow and 20um as distance. Now just divide distance by blood flow = 0.1
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    5 markers that have been:

    -Eukaryotic vs Prokaryotic cells
    -TEM +/-
    -SAN and AVN in cardiac cycle
    -Digestion of starch (enzymes)
    -Absorption of starch
    -Substances across a plasma membrane
    -Lungs adapted to gas exchange
    -Atheroma linking to aneurium (specimen)
    -Smoking/ diet high in sat fat - myocardial infarcation (specimen)

    So I'm guessing we will get one if these:

    -Cholera / ORS
    -Mechanism of breathing
    -Cardiac cycle
    -Asthma
    -Fibrosis
    -Humoural / cell mediated response

    Any others?
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    (Original post by reaperguy)
    how do the SAN and AVN control the cardiac cycle?
    5 marks
    SAN is myogenic? So produces it's own impulse. This electrical impulse stimulates the atria causing it to contract so blood enters the ventrciles duh to an increase in perssure. It also stimulates the AVN where there is a slight delay to allow the ventricles to fill up up with blood. When the AVN is stimulated it relays the impulse to the bundle of His and punkjibe (sp?) fibres which contract the venctricles from the bottom, upwards to cause the ventricles to contract so decrease pressure so blood enters the pulmonary arteries/aorta.
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    Most of that is good but I was looking for other functions aswell such as Cell recognition, Cell communication etc etc..
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    (Original post by BeejTheone)
    Yeah i realised a tad after replying xD
    Haha
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    (Original post by reaperguy)
    how do the SAN and AVN control the cardiac cycle?
    5 marks
    The SAN sends electrical impulses to the atria, it then sends electrical impulses down the bundle of his avoiding the non-conductive tissue seperating the atria and the ventricles, to the purkyne fibres allowing contraction to take place from base upwards. The AVN allows for a short delay before the contractioon takes place, this allows the ventricles to fill up with blood, so they can contract with a full supply of blood. Without this delay less blood would be able to be pumped around the body as the ventricles would not have enough time to fill up. How many marks would I have got?? That was a toughy to get 5?!?
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    (Original post by liviaaa)
    5 markers that have been:

    -eukaryotic vs prokaryotic cells
    -tem +/-
    -san and avn in cardiac cycle
    -digestion of starch (enzymes)
    -absorption of starch
    -substances across a plasma membrane
    -lungs adapted to gas exchange
    -atheroma linking to aneurium (specimen)
    -smoking/ diet high in sat fat - myocardial infarcation (specimen)

    so i'm guessing we will get one if these:

    -cholera / ors
    -mechanism of breathing
    -cardiac cycle
    -asthma
    -fibrosis
    -humoural / cell mediated response

    any others?
    thanks
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    (Original post by BeejTheone)
    Convert all measurements into Um and u get 200um s-1 for blood flow and 20um as distance. Now just divide distance by blood flow = 0.1
    Ah those micrometres stumped me again, didnt even notice :P Thanks
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    (Original post by BeejTheone)
    Most of that is good but I was looking for other functions aswell such as Cell recognition, Cell communication etc etc..
    Oh yeah the glycoprotein and the cholestrol ! Damn ! again lol !
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    (Original post by ??????????????????)
    SAN is myogenic? So produces it's own impulse. This electrical impulse stimulates the atria causing it to contract so blood enters the ventrciles duh to an increase in perssure. It also stimulates the AVN where there is a slight delay to allow the ventricles to fill up up with blood. When the AVN is stimulated it relays the impulse to the bundle of His and punkjibe (sp?) fibres which contract the venctricles from the bottom, upwards to cause the ventricles to contract so decrease pressure so blood enters the pulmonary arteries/aorta.
    yep

    you could have also said for the delay to allow the atria to empty completely before the ventricles contract
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    (Original post by Rickesh)
    Cell membranes prevent large molecules that do not fit through the phospholipid layer, from entering. They also do not allow charged molecules, or molecules that are no lipid soluble. They allow larger molecules such as Sodium to enter through channel proteins, by facilitated diffusion. With the use of ATP molecules that are going against their concentration gradient (low to high) are also allowed to go through the proteins. Gosh i'm really struggling here ! urmm what else is there?
    You could add on to your point that because only small, non-polar molecules enter through with simple diffusion and those that are polar and/or big that have to use the channel proteins so this allows the membrane to control which molecules go to which place.
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    (Original post by liviaaa)
    5 markers that have been:

    -Eukaryotic vs Prokaryotic cells
    -TEM +/-
    -SAN and AVN in cardiac cycle
    -Digestion of starch (enzymes)
    -Absorption of starch
    -Substances across a plasma membrane
    -Lungs adapted to gas exchange
    -Atheroma linking to aneurium (specimen)
    -Smoking/ diet high in sat fat - myocardial infarcation (specimen)

    So I'm guessing we will get one if these:

    -Cholera / ORS
    -Mechanism of breathing
    -Cardiac cycle
    -Asthma
    -Fibrosis
    -Humoural / cell mediated response

    Any others?
    small intestine adapted for absorption?
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    Does anyone know when the mark scheme will be available for this? It was virtually the next day or so for some GCSE exams. Or does it not work like that at AS hmm...
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    (Original post by Rickesh)
    The SAN sends electrical impulses to the atria, it then sends electrical impulses down the bundle of his avoiding the non-conductive tissue seperating the atria and the ventricles, to the purkyne fibres allowing contraction to take place from base upwards. The AVN allows for a short delay before the contractioon takes place, this allows the ventricles to fill up with blood, so they can contract with a full supply of blood. Without this delay less blood would be able to be pumped around the body as the ventricles would not have enough time to fill up. How many marks would I have got?? That was a toughy to get 5?!?
    Mark Scheme answer was this
    1. SAN initiates heartbeat / acts as a pacemaker / 7 (a)
    myogenic;
    2. (SAN) sends wave of electrical activity / impulses
    (across atria) causing atrial contraction;
    3. AVN delays (electrical activity / impulses);
    4. (Allowing) atria to empty before ventricles contract /
    ventricles to fill before they contract;
    5. (AVN) sends wave of electrical activity / impulses
    down Bundle of His / Purkyne fibres;
    6. (Causing) ventricles to contract (from base up) /
    ventricular systole;
    Max 5
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    (Original post by Rickesh)
    Oh yeah the glycoprotein and the cholestrol ! Damn ! again lol !
    how does fibrosis and asthma affect lung function?
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    (Original post by DoaaK)
    small intestine adapted for absorption?
    Maybe.. but it says only digestive system in limited detail on the spec. If it was I think it'd be about the membrane in the small intestine?
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    What is a vaccine?
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    (Original post by reaperguy)
    What is a vaccine?
    Something that contains antigens/weakened microorganisms that invoke an immune response and stimulate antibody production?
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    (Original post by BeejTheone)
    how does fibrosis and asthma affect lung function?
    Pulmonary fibrosis is because of the scarring on the tissue. This scarring reduces the surface area to volume ratio of the lungs, therefore gas exchange is less effiecient. The scarring also mean there is a longer diffusion pathway for the oxygen, therefore the oxygen takes longer to diffuse around the lungs. Asthma, is caused by allergens e.g. pollen that stimulate the white blood cells to produce histamine. The histamine makes the epithelial cells to produce more mucus that normal, and the bronchioles become inflammed. This again increases the surface area : volume ratio, so the oxygen takes longer to diffuse. What else? What would i have got as a mark?
 
 
 
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