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AQA Biology AS New Spec - 26th May and 7th June Watch

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    (Original post by The_queenb)
    it doesn't say anywhere in the new spec that we need to know about cholera specifically like the past specification. But i think it'll be good go gather a bit of knowledge on it just in case.
    Thanks

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    Does anyone know what is exactly meant by 'mass transport'?
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    its the transport of substances(such as sucrose) from the source(where is it made) to the sink(where it needs to go)
    I think they also call it translocation
    you want to know the exact process ?
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    (Original post by SANTR)
    Does anyone know what is exactly meant by 'mass transport'?
    Mass transport is the movement of a large number of particles (ions/molecules etc) in the same direction at a same time.

    It's often due to pressure like in the phloem, during ventilation, and in circulatory systems, and can only happen with fluids. Hope this helped
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    (Original post by neon_reaper)
    Mass transport is the movement of a large number of particles (ions/molecules etc) in the same direction at a same time.

    It's often due to pressure like in the phloem, during ventilation, and in circulatory systems, and can only happen with fluids. Hope this helped
    Could you explain it in the context of circulatory systems, as in how is it a feature of mass transport?
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    (Original post by alyoan tariq)
    so like easy papers can also have low-grade boundaries ?! is this hat ur trying to say ?if this is the case i still have hope for scoring at least a B on my biology paper 3 .
    Easy palers tendto have higher grade boundaries as people get higher marks on them. Grade boundaries are done by looking at the scores of everyone and then having a certain percentage for each grade eg they mighthave it as only the top 10% of people getting an A for that specific paper. They then look at what scores the top eg 10% get and set the boundaries from there
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    Does anybody have predictions for the two 5 markers at the end of paper 2?
    Also any tips on how to get full marks on both of those 5 markers?
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    (Original post by SANTR)
    Could you explain it in the context of circulatory systems, as in how is it a feature of mass transport?
    The circulatory system is unidirectional (all the blood in a given vessel will always flow in one direction) and a large number of particles are present in the blood, both suspended and dissolved (like oxygen and ions) and so are transported as the blood moves.

    Bear in mind that I'm a student as well so these answers aren't necessarily right :/ and the mark schemes in biology are never exactly what you expect
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    Does anyone have a list of some of the questions please? I have a mock on this paper to see whether I get back into sixth form or not next year
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    Hey guys... does anyone know how to do this question from the specimen Paper 2 (see attached)?? the answer is 78-81%, but I am not sure how to work it out...any help would really be appreciated!
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  1. File Type: docx stuck on question 04.2.docx (219.6 KB, 152 views)
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    (Original post by JustWondering98)
    Hey guys... does anyone know how to do this question from the specimen Paper 2 (see attached)?? the answer is 78-81%, but I am not sure how to work it out...any help would really be appreciated!
    At 1 second its approximately 4.1 for the healthy group and 0.9 for the other group so you need to find what % decrease that is. 4.1 - 0.9 = 3.2 which is the decrease. Therefore as a percentage its 3.2/4.1 x 100 = 78%
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    (Original post by neon_reaper)
    At 1 second its approximately 4.1 for the healthy group and 0.9 for the other group so you need to find what % decrease that is. 4.1 - 0.9 = 3.2 which is the decrease. Therefore as a percentage its 3.2/4.1 x 100 = 78%
    Ahh i see...thank you!
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    Any predictions for the paper on Tuesday??
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    Does anyone have a list of 5/6 mark questions which I could prepare for paper2?


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    Could anyone help me understand Monoclonal antibodies? I really don't understand it & the ELISA test if someone could explain it using normal rather than overly scientific language i'd be grateful
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    (Original post by Mubstar)
    Could anyone help me understand Monoclonal antibodies? I really don't understand it & the ELISA test if someone could explain it using normal rather than overly scientific language i'd be grateful
    HERE WE GO.....


    The
    ELISA test has many uses as I am sure you already know. E.g/ cancer patients to attack tumor cells which are slightly different to normal body cells, transplant surgery - to attack the t-cells from the donor and to find antigens/antibodies:

    There are two versions which are taught for our spec:
    -The first is using a test tube/plate which has antibodies at fixed positions. In this test we are using the test to find antigens. An example is when we are looking for antigens related to cancer such as the prostrate specific antigen.

    Step 1) We start off with the antibodies already on the plate.
    Step 2) We add the blood sample from the patient. If the patient has lots of PSA (the cancer antigen) it will bind to the antibodies to make the antigen-antibody complex.
    Step 3) If they form a complex then they will remain bound when the plate is washed. The reason for washing comes up later.
    Step 4) Now we add another antibody, this antibody has a small enzyme attached to it. The antibody will bind to the antigen as well. So in effect, the antigen binds to two antibodies. We now wash to remove any antibody if it didn't bind. If there was no antigen present in the blood, then the antibody we added in this step would not bind as there is no antigen to bind to. This is what it kinda looks like:


    |-< >- =Antigen in blood |-<= Antibody already on test plate
    |-< >- =Enzyme on the second antibody
    |-< >-
    |-< >-

    As you can see, in the first three. The second antibody will bind as the antigen is present. But on the last one, there is no antigen present so >- will be washed away and no colour produced.

    Step 5) We add a substrate, this substrate will react with the enzyme to form an enzyme-substrate complex. Upon forming this, the enzyme breaks down the colourless substrate into a coloured product. So a coloured product is formed only if the antigen is present. We can know do quite a few things from this position. We can look at the intensity of the colour as a measure of the concentration of antigens in the persons blood as MORE ANTIGENS = MORE COLOUR or we can use a colorimeter to measure the conc.

    The way to look for antibodies instead of antigens is similar but instead of starting with an antibody on the plate we start with an antigen.


    As for monoclonal antibodies - all you need to remember is that the are a group of a single type of antibodies and that they have lots of uses. The formation of them is not on our, the new, spec.

    Hope that helped

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    (Original post by Zainab14)
    Does anyone have a list of 5/6 mark questions which I could prepare for paper2?


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    Mitosis
    How does variation arise in meiosis
    DNA replication
    Protein Synthesis - Transcription/Translation
    Cohesion-Tension theory
    Structure of the phloem
    The cardiac cycle.
    Describe the process and outline how each occurs.
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    (Original post by SANTR)
    Does anyone know what is exactly meant by 'mass transport'?
    I believe one mark scheme answer went like this: "The bulk movement of a substance from one location to another".
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    (Original post by SANTR)
    Does anyone know what is exactly meant by 'mass transport'?
    These were the marking points:

    1. Movement over large distances/around plant ororganism;2. (All) substances move together/bulk movement;3. All move at the same speed/quicker thandiffusion;4. All move in the same direction;5. Movement due to pressure (differences);
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    (Original post by RKM21)
    HERE WE GO.....


    The
    ELISA test has many uses as I am sure you already know. E.g/ cancer patients to attack tumor cells which are slightly different to normal body cells, transplant surgery - to attack the t-cells from the donor and to find antigens/antibodies:

    There are two versions which are taught for our spec:
    -The first is using a test tube/plate which has antibodies at fixed positions. In this test we are using the test to find antigens. An example is when we are looking for antigens related to cancer such as the prostrate specific antigen.

    Step 1) We start off with the antibodies already on the plate.
    Step 2) We add the blood sample from the patient. If the patient has lots of PSA (the cancer antigen) it will bind to the antibodies to make the antigen-antibody complex.
    Step 3) If they form a complex then they will remain bound when the plate is washed. The reason for washing comes up later.
    Step 4) Now we add another antibody, this antibody has a small enzyme attached to it. The antibody will bind to the antigen as well. So in effect, the antigen binds to two antibodies. We now wash to remove any antibody if it didn't bind. If there was no antigen present in the blood, then the antibody we added in this step would not bind as there is no antigen to bind to. This is what it kinda looks like:


    |-< >- =Antigen in blood |-<= Antibody already on test plate
    |-< >- =Enzyme on the second antibody
    |-< >-
    |-< >-

    As you can see, in the first three. The second antibody will bind as the antigen is present. But on the last one, there is no antigen present so >- will be washed away and no colour produced.

    Step 5) We add a substrate, this substrate will react with the enzyme to form an enzyme-substrate complex. Upon forming this, the enzyme breaks down the colourless substrate into a coloured product. So a coloured product is formed only if the antigen is present. We can know do quite a few things from this position. We can look at the intensity of the colour as a measure of the concentration of antigens in the persons blood as MORE ANTIGENS = MORE COLOUR or we can use a colorimeter to measure the conc.

    The way to look for antibodies instead of antigens is similar but instead of starting with an antibody on the plate we start with an antigen.


    As for monoclonal antibodies - all you need to remember is that the are a group of a single type of antibodies and that they have lots of uses. The formation of them is not on our, the new, spec.

    Hope that helped

    (Original post by RKM21)
    HERE WE GO.....


    The
    ELISA test has many uses as I am sure you already know. E.g/ cancer patients to attack tumor cells which are slightly different to normal body cells, transplant surgery - to attack the t-cells from the donor and to find antigens/antibodies:

    There are two versions which are taught for our spec:
    -The first is using a test tube/plate which has antibodies at fixed positions. In this test we are using the test to find antigens. An example is when we are looking for antigens related to cancer such as the prostrate specific antigen.

    Step 1) We start off with the antibodies already on the plate.
    Step 2) We add the blood sample from the patient. If the patient has lots of PSA (the cancer antigen) it will bind to the antibodies to make the antigen-antibody complex.
    Step 3) If they form a complex then they will remain bound when the plate is washed. The reason for washing comes up later.
    Step 4) Now we add another antibody, this antibody has a small enzyme attached to it. The antibody will bind to the antigen as well. So in effect, the antigen binds to two antibodies. We now wash to remove any antibody if it didn't bind. If there was no antigen present in the blood, then the antibody we added in this step would not bind as there is no antigen to bind to. This is what it kinda looks like:


    |-< >- =Antigen in blood |-<= Antibody already on test plate
    |-< >- =Enzyme on the second antibody
    |-< >-
    |-< >-

    As you can see, in the first three. The second antibody will bind as the antigen is present. But on the last one, there is no antigen present so >- will be washed away and no colour produced.

    Step 5) We add a substrate, this substrate will react with the enzyme to form an enzyme-substrate complex. Upon forming this, the enzyme breaks down the colourless substrate into a coloured product. So a coloured product is formed only if the antigen is present. We can know do quite a few things from this position. We can look at the intensity of the colour as a measure of the concentration of antigens in the persons blood as MORE ANTIGENS = MORE COLOUR or we can use a colorimeter to measure the conc.

    The way to look for antibodies instead of antigens is similar but instead of starting with an antibody on the plate we start with an antigen.


    As for monoclonal antibodies - all you need to remember is that the are a group of a single type of antibodies and that they have lots of uses. The formation of them is not on our, the new, spec.

    Hope that helped

    (Original post by RKM21)
    HERE WE GO.....


    The
    ELISA test has many uses as I am sure you already know. E.g/ cancer patients to attack tumor cells which are slightly different to normal body cells, transplant surgery - to attack the t-cells from the donor and to find antigens/antibodies:

    There are two versions which are taught for our spec:
    -The first is using a test tube/plate which has antibodies at fixed positions. In this test we are using the test to find antigens. An example is when we are looking for antigens related to cancer such as the prostrate specific antigen.

    Step 1) We start off with the antibodies already on the plate.
    Step 2) We add the blood sample from the patient. If the patient has lots of PSA (the cancer antigen) it will bind to the antibodies to make the antigen-antibody complex.
    Step 3) If they form a complex then they will remain bound when the plate is washed. The reason for washing comes up later.
    Step 4) Now we add another antibody, this antibody has a small enzyme attached to it. The antibody will bind to the antigen as well. So in effect, the antigen binds to two antibodies. We now wash to remove any antibody if it didn't bind. If there was no antigen present in the blood, then the antibody we added in this step would not bind as there is no antigen to bind to. This is what it kinda looks like:


    |-< >- =Antigen in blood |-<= Antibody already on test plate
    |-< >- =Enzyme on the second antibody
    |-< >-
    |-< >-

    As you can see, in the first three. The second antibody will bind as the antigen is present. But on the last one, there is no antigen present so >- will be washed away and no colour produced.

    Step 5) We add a substrate, this substrate will react with the enzyme to form an enzyme-substrate complex. Upon forming this, the enzyme breaks down the colourless substrate into a coloured product. So a coloured product is formed only if the antigen is present. We can know do quite a few things from this position. We can look at the intensity of the colour as a measure of the concentration of antigens in the persons blood as MORE ANTIGENS = MORE COLOUR or we can use a colorimeter to measure the conc.

    The way to look for antibodies instead of antigens is similar but instead of starting with an antibody on the plate we start with an antigen.


    As for monoclonal antibodies - all you need to remember is that the are a group of a single type of antibodies and that they have lots of uses. The formation of them is not on our, the new, spec.

    Hope that helped


    WOW! THANKS SO MUCH!!!! That's great thankyou!!!
 
 
 
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