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    do you guys think it is realy important to do past papers ? ,because for the january I did all the past papers released by the board and I ended up with a horrific grade . I have most of the past papers for this unit but when i went through it , the questions are realy hard and unpredictable and I end up looking at the mark scheme 99% of the time it just frustrates me because i have revised and made notes from the book:mad:
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    (Original post by blueberry123)
    do you guys think it is realy important to do past papers ? ,because for the january I did all the past papers released by the board and I ended up with a horrific grade . I have most of the past papers for this unit but when i went through it , the questions are realy hard and unpredictable and I end up looking at the mark scheme 99% of the time it just frustrates me because i have revised and made notes from the book:mad:
    Only book = 50%
    book + past papers = 99.5%
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    (Original post by blueberry123)
    do you guys think it is realy important to do past papers ? ,because for the january I did all the past papers released by the board and I ended up with a horrific grade . I have most of the past papers for this unit but when i went through it , the questions are realy hard and unpredictable and I end up looking at the mark scheme 99% of the time it just frustrates me because i have revised and made notes from the book:mad:
    Only book = 50%
    book + past papers = 99.5%
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    say in the exam they ask something like explain how the structure of skeletal muscle related to its function, how would you answer this:
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    Gene therapy

    - Treatment of a genetic disorder by altering an individuals genotype
    - Used to treat some recessive conditions e.g. Cystic Fibrosis

    Somatic cell gene therapy
    - Gene is inserted into the target cell
    - Gene cannot be passed on to the next generation

    Germline cell gene therapy
    - Gene in inserted into a zygote/gamete as a result gene is in every body cell, so is in the cells that give rise to the reproductive cells >>> gene can be passed on to the next generation

    Issues
    Somatic
    - technique is needed to get the gene to the target cell
    - treatment is short lived, so needs to be repeated regularly.

    Germline
    - Unethical - illegal in the UK


    Xenotransplantation
    - transplantation between species e.g. Humans and Pigs.

    Issues - Pigs

    - Immune rejection - transplanted organ is destroyed unless it is a very close match. Patients are treated with immunosuppressant drugs - could have serious side effects.
    - Different organ sizes
    - Shorter life span compared to that of humans
    - Body temperature - 39°C - 2°C above that of humans.

    Pigs have been genetically engineered by inserting genes for:
    - Cells surface proteins - stops the complement system (part of the immune system) from attacking the transplanted organ
    - Cell surface antigens - used in cell recognition
    - Enzymes which regulate anti-apoptosis genes - prevents programmed cell death on transplanted organ.


    Ethical concerns raised by genetic manipulation

    Microorganisms
    +

    - GM microorganisms produce useful products such as human insulin and the human growth hormone
    -
    - GM microorganisms may escape - transfer genes to pathogenic microogranisms
    - Antibiotic resistant genes (markers) - may spread, causing widespread antibiotic resistance.

    Plants
    +
    - Herbicide resistant - increase yield
    - Weed killer can be sprayed
    - Production of Golden rice
    -
    - All plants may become herbicide resistant - 'super weeds' - causes loss of biodiversity, reduces genetic variation
    - Toxic

    Animals
    +

    - Increase milk/meat production
    - Human proteins produced in milk of transgenic sheep
    -
    - Religious views - Muslims, Jews
    - Animal welfare issues - animal cruelty

    Humans
    +
    - Gene therapy is used to treat some genetic disorders
    -
    - Tampering with DNA is considered to be unnatural
    - Future generations do not have a say in modifying their genetic material.
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    (Original post by TX22)
    say in the exam they ask something like explain how the structure of skeletal muscle related to its function, how would you answer this:
    Skeletal muscle has:
    1) Many mitochondria in muscle fibres to provide ATP for muscle contraction via oxidative phosphorylation
    2) Many muscle fibres, and myofilaments/sarcomeres so many simultaneous contractions result in the entire muscle contracting
    3) Held to bone so it can be used for movement by tendons
    4) It has a specialised membrane, the sarcolemma which contains receptors and its highly folded into the sarcoplasm, this forms transverse (T) tubules which help spread the depolarisation through the entire muscle fibre
    5) Has Sarcoplasmic reticulum which is specialised to release Ca2+ ions when depolarisation occurs in them muscle fibre and also stores the Ca2+ ions after stimulation of the muscle fibre has occurred (moved by active transport back into it)
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    (Original post by TX22)
    say in the exam they ask something like explain how the structure of skeletal muscle related to its function, how would you answer this:
    Skeletal muscles/voluntary muscles are attached to bone by tendons, and the antagonistic working of the muscles allows for movement of the bone at the joint. They are made up of cells, that are elongated to form fibres, and are surrounded by a sarcollema. The muscles cell cytoplasm, the sarcoplasm, contains a large amount of mitochondria, so allows for large quanities of ATP to be generated through oxidative phosphorylation, wherby H+ ions are transported to the intermembrane space, and can diffuse through ATP synthase to allow ADP and Pi to be joined by rotor action of the enzyme to make ATP which will be available to the myofibrils which are the contractile units of the muscle. ATP is a vital component to enable muscle contraction, as shown by the sliding filament model. In order to form, and reform cross bridges, to allow for the myosin and actin filaments to slide past one another and decrease the Z line, the myosin head requires an input of ATP to allow it to move back into its bent position, so it can re-bind to the actin filament again, while releasing ATP as ADP and Pi. Within the sarcoplasm there are also extensive sarcoplasmic reticulum, and these hold stores of Ca 2+ ions which control the contraction that occurs within the myofibrils. As it is the release of Ca 2+ ions that cause the movement of the tropomyosin molecule that leaves the actin binding site open so that the mysoin head can bind to the actin filament and contraction can occur.
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    ExamQuest pleaseeeeeee!!!

    I've done all the questions using the ones generated from the Demo Software, I beg one of you to please get all the questions for F215 these are just brilliant, please go ask your teacher they can send you all of them + Mark scheme. Makes past paper revision way better, so you can practice each topic in turn. Here's the ones from the ExamQuest Demo Program.
    Attached Files
  1. File Type: rtf F215 Questions.rtf (457.8 KB, 620 views)
  2. File Type: rtf F215 Mark Scheme.rtf (93.7 KB, 122 views)
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    (Original post by majid81)
    ExamQuest pleaseeeeeee!!!

    I've done all the questions using the ones generated from the Demo Software, I beg one of you to please get all the questions for F215 these are just brilliant, please go ask your teacher they can send you all of them + Mark scheme. Makes past paper revision way better, so you can practice each topic in turn. Here's the ones from the ExamQuest Demo Program.
    Pfff, that is exactly the specimen paper!

    Thanks for trying though, lets hope someone can get on the "real" ExamQuest.
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    could anyone help me out with this syllabus point?

    - Explain how plant responses to environmental
    changes are co-ordinated by hormones, with reference to responding to changes in light direction.
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    (Original post by aimz08)
    could anyone help me out with this syllabus point?

    - Explain how plant responses to environmental
    changes are co-ordinated by hormones, with reference to responding to changes in light direction.
    Think it's phototropism. Auxin accumultes on the shaded side, so the cells elongate on that side and the shoot bends towards the light.
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    Although the spec says we need to be able to 'outline the structural and functional differences between voluntary, involuntary and cardiac muscle'; do we need to know why their structure is suited to their function / how each muscle type is adapted to their function?

    I can imagine them setting an exam question with a similar wording :/
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    (Original post by smflesh)
    Although the spec says we need to be able to 'outline the structural and functional differences between voluntary, involuntary and cardiac muscle'; do we need to know why their structure is suited to their function / how each muscle type is adapted to their function?

    I can imagine them setting an exam question with a similar wording :/
    I think theyre likely to ask about skeletal muscle because weve done that and how its specialised, cardiac muscle is a maybe (like intercalated discs which allows action potentials to diffuse quickly and easily between the interconnected fibres) because we covered stimulation and contraction in AS.
    I doubt theyll ask too much about involuntary/smooth muscle though as we havent covered that in depth really about adaptions.
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    (Original post by aimz08)
    could anyone help me out with this syllabus point?

    - Explain how plant responses to environmental
    changes are co-ordinated by hormones, with reference to responding to changes in light direction.

    The refers to phototropism- where a shoot will grow towards a light source in order to get enough light for photosynthesis.
    The hormones involved in this case are auxins. Auxins promote cell elongation, inhibit leaf abscision and the growth of lateral buds. The phototropic response is shown by the following:

    By allowing the plant to be surrounded by light of equal intensity from all sides, the auxins that are produced in the apex will diffuse along the cells in the zone of elongation evenly, so the shoot will grow vertically.

    If the plant is only subject to light from one side, then auxins diffuse away from the light source (it is though that 2 enzymes are involved in this process, which causes the auxins to do this) so the shaded side elongates faster than the illuminated side, thus the shoot will bend towards the light source.
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    Hey can u peeps jus help me out with this:

    I want to know, what would you write in the exam if the question asks "Explain the discrepancy between the actual and expected results of the test cross". (Chi Squared Test)..I just dont seem to get the question.. Thankyou
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    (Original post by Aftermath_Fan)
    Hey can u peeps jus help me out with this:

    I want to know, what would you write in the exam if the question asks "Explain the discrepancy between the actual and expected results of the test cross". (Chi Squared Test)..I just dont seem to get the question.. Thankyou
    Well, if from your Chi-squared test you get a value that is lower than that present in the critical region for your certain no. of degrees of freedom then you can assume that any differences in observed and expected no's are due to chance, but if you get a value that is higher than the given value in the tables, it is not due to chance, and you have to suggest why this is the case. For example the specific cross that you get may be more similar to 1:2:1, in this case it would show that codominance is occuring.
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    :creep:
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    Does the bending of the myosin head group to pull the thin actin filaments use energy from ATP --> ADP + Pi?

    The book says 'ADP and Pi' are released after the head bends, but has no mention of energy use.
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    (Original post by smflesh)
    Does the bending of the myosin head group to pull the thin actin filaments use energy from ATP --> ADP + Pi?

    The book says 'ADP and Pi' are released after the head bends, but has no mention of energy use.
    As far as I'm aware it does. The release of ADP + Pi is because of the use of ATP
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    (Original post by InvoluntarySlacker)
    :creep:
    :hi:

    Some stuff people are on about in this thread make me just want to... - Im leaving this thread for now, gotta focus on F211 first...:

    :getmecoat:
 
 
 
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