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    afternoon 1.30
    im quite confident seeing as i have been revising since september haha i just cannot wait to get this exam over with! then all i have is chemistry and psychology, which are just equally as bad haha

    when is your exam?
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    (Original post by emmachewit)
    does anyone know what we need to know about human life expectancy in the AQA exam? is it just applying it to pyrimads or is there more too it?
    also do we need to know about allopatric speciation and sympatric? or just that speciation includes geographical and reproductive ioslation. :confused:
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    (Original post by emmachewit)
    does anyone know what we need to know about human life expectancy in the AQA exam? is it just applying it to pyrimads or is there more too it?
    Yes I think that is correct. Maybe just to explain if they are increasing, decreasing/stable population. Also that human life expectancy is the age when at least 50% of the people in a particular population are alive.
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    righteo, thanks alot
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    can anyone upload the jan 2010 paper? if so, please quote me and upload it..cheers...
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    (Original post by mmaa)
    can anyone upload the jan 2010 paper? if so, please quote me and upload it..cheers...
    Here you go :
    Attached Files
  1. File Type: zip AQA BIOL4 JAN 2010.zip (186.4 KB, 67 views)
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    Do we have to know about the sex-linked disease Haemophilia coz the specification doesnt say anything about it?

    In chapter 5, 7 and so on there are some application questions where they ask you to outline arguments for and against for something like egg production by keeping the hen in battery cages. Some application questions also ask to discuss about the ethical issues. Do we have to learn/memorise these arguments and ethical issues for the unit 4 exam?
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    (Original post by mithi25)
    Do we have to know about the sex-linked disease Haemophilia coz the specification doesnt say anything about it?

    In chapter 5, 7 and so on there are some application questions where they ask you to outline arguments for and against for something like egg production by keeping the hen in battery cages. Some application questions also ask to discuss about the ethical issues. Do we have to learn/memorise these arguments and ethical issues for the unit 4 exam?
    We don't need to know about specific diseases, I believe, because we can be asked about any disease and we're expected to apply our knowledge; which is why it's a good idea to practise some of them (just to get an idea of what we may be asked in the exam).

    And for your second question, the answer is yes; although not in great detail, but we need to be able to outline advantages and disadvantages. I presume a 2marks question would be: give two reasons why keeping chicken in cages may be regarded as unethical. :dontknow:
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    (Original post by algérie_mon_amour)
    We don't need to know about specific diseases, I believe, because we can be asked about any disease and we're expected to apply our knowledge; which is why it's a good idea to practise some of them (just to get an idea of what we may be asked in the exam).

    And for your second question, the answer is yes; although not in great detail, but we need to be able to outline advantages and disadvantages. I presume a 2marks question would be: give two reasons why keeping chicken in cages may be regarded as unethical. :dontknow:
    thanks a lot
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    (Original post by algérie_mon_amour)
    Here you go :
    i just found it elsewhere, but thank you anyway
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    Also i believe that water is a factor that contributes greatly to photosynthesis (
    i.e. for photolysis of water molecule to supply the replacement electron to potosystem 2 on the membrane of the thylakoids during light dependent reaction of photosyntheses also we have to remember that the cell cytoplasm consists of 70% water)
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    (Original post by jimmy303)
    "Outline the main factors that can affect on the rate of photosynthesis."

    There are three (arguably four) main factors that affect the rate of photosynthesis: atmospheric carbon dioxide concentration, light intensity, temperature, and atmospheric oxygen concentration in C3 plants. Others exist such as wavelength of light etc. that I won't go into.

    A high carbon dioxide concentration increases the number of reactions that rubisco catalyses. This means that GP is formed at a faster rate, increasing the rate that the products of the light-independent reaction, i.e. hexose sugars, are produced (more is produced in the same amount of time). However, too much carbon dioxide damages the leaves of the plant, so an optimum concentration is needed.

    An increase in light intensity affects the light-dependent reactions so that the rate of photosynthesis increases (due to more excited electrons at a faster rate, producing more ATP and NADPH for the the light-independent reaction) until the photosynthetic pigments in the thylakoid membranes have become saturated with light. The removal of light intensity will stop the excitement of electrons and so no ATP or NADPH will be produced. ATP and NADPH are needed in the light-independent reaction to convert glycerate 3-phosphate to to triose phophate (ATP provides the energy, NADPH provides hydrogen) and so no hexose sugars are formed and the GP is not regenerated into RuBP.

    An increase in temperature will increase the kinetic energy of the reactants of the light-independent stage, increasing the probability of RuBP combining with carbon dioxide. It also increases the efficiency of rubisco, the catalyst of the reaction between these two substrates. This increases the rate of photosynthesis. However, if the temperature gets too high, the enzyme rubisco becomes denatured as bonds break, so that the reaction cannot occur, reducing the rate of photosynthesis.

    Oxygen and carbon dioxide compete for the same active site on rubisco. Consequently, photorespiration occurs whereby RuBP is oxidised to form only one molecule of GP (as opposed to two) and some by-products, halving the efficiency of photosynthesis.

    Have fun with this one: :p:
    The green pigment in a particular plant is caused by the dominant allele G. The yellow pigment is caused by the recessive pigment g. Complete a genetic cross between two parents heterozygous for this. Show each stage (e.g. parent genotypes) clearly.


    Also i believe that water is a factor that contributes greatly to photosynthesis (
    i.e. for photolysis of water molecule to supply the replacement electron to potosystem 2 on the membrane of the thylakoids during light dependent reaction of photosyntheses also we have to remember that the cell cytoplasm consists of 70% water)
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    Also i believe that water is a factor that contributes greatly to photosynthesis (
    i.e. for photolysis of water molecule to supply the replacement electron to potosystem 2 on the membrane of the thylakoids during light dependent reaction of photosyntheses also we have to remember that the cell cytoplasm consists of 70% water)
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    This thread seems to have come to a pause. 4 days people !

    What is a demographic transition ? And how would you calculate a population growth ?

    This was posted from The Student Room's Android App on my GT-S5570
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    anyone know how to calculate birth rate/death rate? i struggle applying the equation to the question :/
 
 
 
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