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

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    Hi all,

    I just want to ask. I have been doing some of the old 'legacy' spec past papers and I am unsure about how much we should know about digestion. DO we need to know about endo/exo peptidases? Is it only Starch digestions that we need to know for the new spec?
    Because I am not 100% sure
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    As everyone seems to agree on the fact that immunity will come up, would anyone care to summarise the topic. General or great detail, up to you but I think it will be good revision and it would help me a lot as its my weakest topic. Topic 1,2 and 3 are really easy. 4 and 5 average. 6 is the hardest in my opinion and am really worried after reading this thread

    This is what I know so far (not much I know):

    physical barriers: skin is very thick.
    Chemical barriers: oils on skin, hydrochloric acid in stomach, tears, urine, mucus in lungs.

    2nd line of defence is called the inflammatory response. It is controlled by white blood cells called phagocytes. It is non specific. The process is called phagocytosis. These are the steps of phagocytosis:

    1) phagocyte engulfs the pathogen
    2) pathogen is enclosed into a vesicle/phagosome
    3) Lysosomes in the phagocyte contain digestive enzymes which hydrolize the pathogen

    If the inflammatory response does not kill the pathogen, then it is left to the specific immune response called humoral and cellular

    The cellular is to do with T cells and the humoral response is to do with B cells. B cells secrete antibodies whereas T cells do not.
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    (Original post by nasira372)
    As everyone seems to agree on the fact that immunity will come up, would anyone care to summarise the topic. General or great detail, up to you but I think it will be good revision and it would help me a lot as its my weakest topic. Topic 1,2 and 3 are really easy. 4 and 5 average. 6 is the hardest in my opinion and am really worried after reading this thread

    This is what I know so far (not much I know):

    physical barriers: skin is very thick.
    Chemical barriers: oils on skin, hydrochloric acid in stomach, tears, urine, mucus in lungs.

    2nd line of defence is called the inflammatory response. It is controlled by white blood cells called phagocytes. It is non specific. The process is called phagocytosis. These are the steps of phagocytosis:

    1) phagocyte engulfs the pathogen
    2) pathogen is enclosed into a vesicle/phagosome
    3) Lysosomes in the phagocyte contain digestive enzymes which hydrolize the pathogen

    If the inflammatory response does not kill the pathogen, then it is left to the specific immune response called humoral and cellular

    The cellular is to do with T cells and the humoral response is to do with B cells. B cells secrete antibodies whereas T cells do not.
    Sounds about right, i don't think you have much to worry about. Not heard of 'inflammatory response', i don't think its on the spec, phagocytes come under cellular response as far as I was aware.

    Antibody functions:

    1. Coat pathogen so easier for phagocyte to engulf
    2. Coat pathogen to prevent it from entering host cells
    3. Binding to and neutralising toxins produced by pathogen.

    Also remember antibodies are proteins, with variable regions, much like enzyme acive site.

    T cells help activate B-cells and also some attach to antigens on pathogen and kill it.

    B cells are activated when antibody on surfacer meets complementary antigen and when t cells release substance.

    Activated b cell (with correct complementary antibody to antigen) divides into plasma cells (clones)
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    (Original post by reaperguy)
    Hi all,

    I just want to ask. I have been doing some of the old 'legacy' spec past papers and I am unsure about how much we should know about digestion. DO we need to know about endo/exo peptidases? Is it only Starch digestions that we need to know for the new spec?
    Because I am not 100% sure
    General digestive system: stomach, intestine etc, glands.
    proteins: structure, function, test
    carbohydrates: structure function, test. Basic starch structure and iodine test.
    Lipids: triglycerides and phospholipids, structure, function, test
    Digestion of glucose (diffusion first, then cotransport followed by facilitated diffusion).

    The spec is on the AQA website here: http://web.aqa.org.uk/qual/gce/pdf/AQA-2410-W-SP.PDF
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    (Original post by nasira372)
    As everyone seems to agree on the fact that immunity will come up, would anyone care to summarise the topic. General or great detail, up to you but I think it will be good revision and it would help me a lot as its my weakest topic. Topic 1,2 and 3 are really easy. 4 and 5 average. 6 is the hardest in my opinion and am really worried after reading this thread

    This is what I know so far (not much I know):

    physical barriers: skin is very thick.
    Chemical barriers: oils on skin, hydrochloric acid in stomach, tears, urine, mucus in lungs.

    2nd line of defence is called the inflammatory response. It is controlled by white blood cells called phagocytes. It is non specific. The process is called phagocytosis. These are the steps of phagocytosis:

    1) phagocyte engulfs the pathogen
    2) pathogen is enclosed into a vesicle/phagosome
    3) Lysosomes in the phagocyte contain digestive enzymes which hydrolize the pathogen

    If the inflammatory response does not kill the pathogen, then it is left to the specific immune response called humoral and cellular

    The cellular is to do with T cells and the humoral response is to do with B cells. B cells secrete antibodies whereas T cells do not.
    Ive revised solely from the CGP along with Markscheme revision. Do you think this will be enough in order to get an A. I pretty much understand everything in a simplistic manner but I'm not sure if the CGP lacks vital pieces of information having read some over complicated answers in this thread??
    p.s everything answer in the markscheme for the previous 4 papers on AQA website is in the CGP!
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    (Original post by A_clizzy)
    Ive revised solely from the CGP along with Markscheme revision. Do you think this will be enough in order to get an A. I pretty much understand everything in a simplistic manner but I'm not sure if the CGP lacks vital pieces of information having read some over complicated answers in this thread??
    p.s everything answer in the markscheme for the previous 4 papers on AQA website is in the CGP!
    The CGP is all I use to revise, and if it wasn't for my failure with maths and HSW, It would be getting me As.

    Please ignore some of the answers, inflammatory response is NOT on the AQA spec and writing a university level essay on a principle of biology will get you nowhere in the exam. Been there done that, AQA like sharp succint points for marks, not a long winded essay.
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    (Original post by Tericon)
    The CGP is all I use to revise, and if it wasn't for my failure with maths and HSW, It would be getting me As.

    Please ignore some of the answers, inflammatory response is NOT on the AQA spec and writing a university level essay on a principle of biology will get you nowhere in the exam. Been there done that, AQA like sharp succint points for marks, not a long winded essay.
    The answer which Nasira gave is solely from the Nelson Thornes textbook endorsed by AQA, so it is reasonable.
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    The exam is tommorow
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    Wow, this thread has become a good source of revision!
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    Is anyone any good at pressure and volume changes of the heart? I think that's quite hard.
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    (Original post by liviaaa)
    When it first enters the body a non-specific response will occur. This includes inflammation, so the capilaries become more permeable and more white blood cells can escape. A fever will also occus, raising the body temperature which causes damage to the pathogens. Phagocytosis will also occur - chemicals called medicators are released which attract phagocycotic cells, they engulf bacteria closing them in phagosomes. Lysosomes then migrate towards it and secrete hydrolytic enzymes and digest the microorganism.

    If not destroyed then the specficic response..
    This is way too specific for biol1 mark schemes.
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    my answers are more like..

    phagocytes identify forein antigen on pathogen. They are the first to respond by phagocytosis. Cytoplasm engulfs pathogen, Pathogen then contained in phagocytic vacuole in Cytoplasm. Lysosome organelle containing lysomal enzymes fuses with phagocytic vacuole thus enzymes break down pathogen. Phagocytes presents pathogen's antigen on it own suface to activate other immune system cells such as... T cells etc

    I believe AQA are just looking for simplistic points because according to markscheme they give marks merely for certain words.
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    (Original post by Sparkly-Star)
    Is anyone any good at pressure and volume changes of the heart? I think that's quite hard.
    Well the pressure and volume changes are a pretty simple concept once you get your head around them:

    I try to imagine the pressure and volume changes in sync with the actual cardiac cycle which is: Atria Contract and Ventricles relaxed > Atria Relaxed and Ventricles Contract > Atria Relaxed and Ventricles Relaxed.

    In the first stage the pressure in the atria is greater than the pressure in the ventricles, so the atrio-ventricular valves open and blood flows into the ventricles, which causes volume in the atria to decrease and the volume of the ventricles to increase.

    Then in the second stage, after the delay from the AVN has caused the ventricles to begin contracting(make sure to mention from the base up!) the pressure in the ventricles is greater than the pressure in the atria so the atrio-ventricular valves close. The pressure in the ventricles after contraction is also higher than in the aorta so the semi-lunar valves open and the blood flows into the aorta(or pulmonary artery on the right side of the heart) and volume in the ventricles decrease.

    In the third stage the ventricle and atria are both relaxed and the pressure in the aorta is greater than in the ventricles to the semi lunar valves close, and blood begins to passively flow into the atria and into the ventricles, before the cycle repeats so the volume of both the atria and ventricles is passively increasing at this point.
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    (Original post by TlanTlan)
    This is way too specific for biol1 mark schemes.
    Okay thanks It was in my textbook but I guess it's gone into too much detail.

    --

    Can anyone help me.. iis the initial line of defence and primary response different? Is the initial the physical/chemical barriers, and the primary the first time the antigen enters with the specific response?
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    What topics should I be revising for the most?
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    does anyone want to do a question and answer thign to help revision? ive done all the past papers and gone over the book so many times and done all the exam style questions, i cant think of anythign else to do for revision

    a person suffering from pulmonary fibrosis may become weak and tired during exercise. explain why (5marks)
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    (Original post by liviaaa)
    Okay thanks It was in my textbook but I guess it's gone into too much detail.

    --

    Can anyone help me.. iis the initial line of defence and primary response different? Is the initial the physical/chemical barriers, and the primary the first time the antigen enters with the specific response?
    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
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    (Original post by emmaaa65)
    does anyone want to do a question and answer thign to help revision? ive done all the past papers and gone over the book so many times and done all the exam style questions, i cant think of anythign else to do for revision

    a person suffering from pulmonary fibrosis may become weak and tired during exercise. explain why (5marks)
    Your stressin, if i were yu id start looking at keywords, AQA is VERY picky, you basically have to write the answer exactly how it is in the markscheme otherwise yu wont get the mark...so yeah keywords are really important
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    (Original post by sa258)
    What topics should I be revising for the most?
    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
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    (Original post by emmaaa65)
    does anyone want to do a question and answer thign to help revision? ive done all the past papers and gone over the book so many times and done all the exam style questions, i cant think of anythign else to do for revision

    a person suffering from pulmonary fibrosis may become weak and tired during exercise. explain why (5marks)
    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?
 
 
 
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