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

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    (Original post by emmaaa65)
    whilst it would be safe to go over everything, i have a feeling the heart may come up in quite a bit of detail, so maybe revise the SAN and AVN nodes and how the heart is myogenic. also revise pressure changes within the heart and how the valves are forced open by these differences in pressure
    There's already been a 5 marker on the SAN/AVN, so maybe more the stages of the heart cycle?
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    (Original post by emmaaa65)
    i think so... the initial line of defence is the physcial barriers such as the skin, HCl acid in the stomach, mucus and enzymes to PREVENT the pathogen from entering the body and damaging host cells/producing toxins. however if the defences fail, the RESPONSES take place which are either non-specific or specific. im not really sure if thats actually answered your question but yeah.. lol
    Okay thanks!
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    (Original post by EffKayy)
    The answer which Nasira gave is solely from the Nelson Thornes textbook endorsed by AQA, so it is reasonable.
    Yes, but it is not on the specc. All we are tested on in that area is phagocytes, t cells, b cells, antibodies and how they interact with each other, as well as the terms cellular and humoral response. I just think overcomplicating it doesn't help, you tend to write more and it just wastes time, im one of thoe people who never has enough time in exams because i write so much
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    Okay.. defintion: What are monocolonal antibodies?
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    (Original post by liviaaa)
    I'll do it in bullet points:
    -Scar tissue due to inhaling asbestos/grinding metal/mouldy hay
    -Therefore thicker exchange surface, slower diffusion
    -Alveoli twisted out of shape
    -Obstructed airways - less oxygen
    -Less surface area, longer diffusion pathway - hence lower conc. grad, and slower diffusion
    -Less diffusion, less oxygen to respiring tissues, so less respiration, hence feel tired.

    However I think the main symptoms are shortness of breath and cronic cough to try and remove scar tissue?
    yeah i think those are basivcally the main points, i would have said

    scars that form on the epithelium of the lungs cause them to become thickened, meaning the diffusion pathway for oxygen is longer so the rate of diffusion into the blood deacreses. also, the scar tissue decreases the volume of the lungs meaning less air can be inhaled and the concentration gradient of oxygen in the alveoli is reduced, hence less oxygen diffuses into blood capillaries. the fibrous scars also cause the elastin of the lungs to be reduced, therefore expulsion of air becomes difficult, again meaning less air is inhaled and less is absorbed into the blodd by diffusion. This points unltimately mean that less oxygen is tranported to tissues and muscles via the blood, therefore respiration rate decreases and less ATP (energy) produced, leading to tiredness and fatigue



    yeah the main symptoms are shortness of breath and chronic cough, i think i got confused between fibrosis and emphysema lol
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    (Original post by liviaaa)
    Okay.. defintion: What are monocolonal antibodies?
    Specific antibodies cloned from a group of genetically identical B-cells
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    (Original post by liviaaa)
    Okay.. defintion: What are monocolonal antibodies?
    monocolonal antibodies are antibodies that are identical in structure and therefore will respond to the same type fo antigen


    what is the difference between passive and active immunity?
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    Describe How high Low Density Lipoprotein concentrations in the blood, can lead to coronary heart disease and death by myocardial infarction.
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    (Original post by liviaaa)
    There's already been a 5 marker on the SAN/AVN, so maybe more the stages of the heart cycle?
    do you mean like systole and diastole? all that stuff
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    Describe the advantages of electron microscopes over light microscopes. (2)
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    (Original post by TlanTlan)
    Describe How high Low Density Lipoprotein concentrations in the blood, can lead to coronary heart disease and death by myocardial infarction.
    if the concentration of LDLs in the blood is high they will become incoporated (along with white blood cells) in the walls of the arteries to form an atheroma. atheromas will narrow the lumen of the blood vessels, restricting the flow of blood and hence the supply of oxygen to the muscles/tissues it is supplying. if an atheroma ruptures it can also lead to a thrombosis, which forms a blot clot, further restricting or even blocking completely the flow of blood. If an atheroma occurs in the coronary arteries the heart muscle will be deprived of oxygen and will therefore die as a result, leading to a myocardial infarction which can be fatal.
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    (Original post by Sparkly-Star)
    Describe the advantages of electron microscopes over light microscopes. (2)
    eletron microscopes involve a beam of electrons, which have a lower wavelength therefore the resolution is higher compared to light microscopes, which have a relatively low resolution
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    hey whats up guys
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    (Original post by TlanTlan)
    Describe How high Low Density Lipoprotein concentrations in the blood, can lead to coronary heart disease and death by myocardial infarction.
    Lipoproteins are found in atheromas which can accumulate in cornoary arteries after damage to the lumen, usually by high blood pressure.

    First, lipids and white blood cells accumulate under the lining of the endothelium to form fatty streaks, over time, more lipids and white blood cell as well as connective tissue form a hard plaque known as an atheroma. These can partially block the lumen of cornoary arteries, restricting blood flow, increasing blood pressure. Coronary heart disease is when coronary arteries have lots of atheromas.

    Atheromas can cause thrombosis, atheromas can somtimes rupture the endothelium lining and platelets and fibrin will accumulate at site of damage, forming a blood clot. This can completely block a coronary artery or can become dislodged and block others in the body.

    Restricting the blood flow to the heart can cause a myocardial infaraction. Blood carries O2, needed by the heart muscle to respire. If the heart muscle doesn't get enough O2, it can cause damage or death of heart muscle - the myocardial infarction.
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    (Original post by Sparkly-Star)
    Describe the advantages of electron microscopes over light microscopes. (2)
    Advs:
    -Higher resolving power
    -Greater Magnification

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    (Original post by emmaaa65)
    do you mean like systole and diastole? all that stuff
    Yes
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    (Original post by TlanTlan)
    Describe How high Low Density Lipoprotein concentrations in the blood, can lead to coronary heart disease and death by myocardial infarction.
    I don't think they'll ask as specific as this? They only say in the spec relationships between myocardial infarcation and either smoking, high blood pressure, blood cholesterol and diet.
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    (Original post by liviaaa)
    Advs:
    -Higher resolving power
    -Greater Magnification

    I would write the first point but the other point should be: beams of electrons have a shorter wavelength than light.
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    (Original post by Sparkly-Star)
    I would write the first point but the other point should be: beams of electrons have a shorter wavelength than light.
    All 3 have been on previous mark schemes. You could also mention 3D image, unless it specifies TEM rather than SEM.
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    Describe the structure of an antibody.
 
 
 
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