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AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011 watch

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    (Original post by Cyanohydrin)
    Would you call the opening of pressure gated sodium channels say as the effector?
    Ah, I can see what you mean.I don't think I'd use the word effector as that is generally used when talking about different nerve connections.

    But I would mention positive feedback. An effector has to be a muscle ,organ or gland.

    Why are you inclined to use the word effector:?
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    (Original post by mariiahgac)
    Mmmmm just got confused why ACh would decrease heart rate rather than increasing it
    It's what the book says. Although I really hate using that as an argument to prove a point. I use the CGP book, but the NT book doesn't say anything about specifc hormones, so don't worry about it, in the past paper questions I've come across, it hasn't asked for Acetylcholine or Adrenaline/Noradrenaline as decreasing/increasing heart rate. No specific menion/requirement in our spec, either.
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    (Original post by mariiahgac)
    wouldnt acetylcholine increase the heart rate tho? :/ its an excitatory neurotransmitter
    All neurotransmitters have different properties depending on where they are acting. So acetylcholine may inhibit the SAN but stimulate the gut.
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    (Original post by arvin_infinity)
    Maybe they are parasympathetic neurotransmitters

    slightly off the topic
    Someone kindly correct me if am wrong :

    Progesterone inhibits FSH - LH
    In high conc. Stimulate FSH-LH

    Oestrogen Inhibits LH

    DUnno if there are anymore feedbacks :rolleyes:
    Er what? I thought it was Oestrogen inhibits FSH at low conc. and stimulates LH and FSH at high conc. whereas Progesterone just inhibited both FSH and LH.
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    (Original post by arvin_infinity)
    Maybe they are parasympathetic neurotransmitters

    slightly off the topic
    Someone kindly correct me if am wrong :

    Progesterone inhibits FSH - LH
    In high conc. Stimulate FSH-LH

    Oestrogen Inhibits LH

    DUnno if there are anymore feedbacks :rolleyes:
    Insulin - glucose to glycogen
    Glucagon - glycogen to glucose


    Temp feedback loop

    Heart rate (during exercise) feedback loop

    Blood pressure feedback loop.

    These would be on my list.

    Edit: @scrubby - I agree - Oestorgen at low conc inhibits FSH and LH and at high conc stimulates their production.
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    (Original post by mariiahgac)
    Mmmmm just got confused why ACh would decrease heart rate rather than increasing it
    Acetyl choline and all other neurotransmitters effect the organ where they are acting in different ways. So ACh might decrease activity of SAN but increase activity of skeletal muscle!
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    (Original post by flowerscat)
    Insulin - glucose to glycogen
    Glucagon - glycogen to glucose


    Temp feedback loop

    Heart rate (during exercise) feedback loop

    Blood pressure feedback loop.

    These would be on my list.
    Oops..I meant to say feedback for menstrual cycle
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    (Original post by arvin_infinity)
    Maybe they are parasympathetic neurotransmitters

    slightly off the topic
    Someone kindly correct me if am wrong :

    Progesterone inhibits FSH - LH
    In high conc. Stimulate FSH-LH

    Oestrogen Inhibits LH

    DUnno if there are anymore feedbacks :rolleyes:
    Menstrual Cycle Feedbacks

    POSITIVE FEEDBACK

    • LH stimulates the production of the corpus leuteum, which produced progesterone but also a bit of oestrogen, which stimulates the further production of LH, which means further oestrogen is produced. This causes ovulation.

    NEGATIVE FEEDBACK

    • FSH stimulates follicle development, which stimulates the ovaries to produce oestrogen, which inhibits FSH, so only that ONLY ONE follicle is developed.
    • LH produces the corpus leuteum, which produces progesterone, which inhibits LH production.
    • More oestrogen inhibits FSH, which results in less oestrogen being produced.
    • More progesterone inhibits LH so less progesterone is produced by the Corpus Luteum.

    Why is positive feedback not considered to not be a part of homeostasis?

    • Because postive feedback doesn't keep internal environments constant;
      It amplifies the departure - effectors work to further increase the departure away from normal levels.



    Oestrogen's a funny one. It inhibits FSH and LH, but at high levels, stimulates FSH and LH production, so that's both negative feedback at first and positive feedback at high levels.
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    @arvin_infinity LOL!
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    Hows everyone feeling about this exam?
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    (Original post by Boo!xx)
    Hows everyone feeling about this exam?
    Im not too worried. They arent too strict about marking the essay and I like this unit .
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    Can someone please clarify what the ATP actually does in relation to the myosin head during the sliding filament mechanism? Does it just provide the energy for filaments to slide or does it provide energy to break the actin-myosin cross bridge aswell? I'm using the text book, CGP revision guide and Heck Grammar notes - but none have given me a definitive answer. Cheers lads + gals.
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    I have a question, with the genetic screening, one of the stages for finding the mutated gene of the individual is that the PCR technique is used to produce multiple copes of the DNA probe (referring to nelson thornes book page 272). But I thought PCR was for double stranded DNA, it separates them and forms a complementary strand on each strand. Whereas the mutated gene for genetic screening is only a single strand (as shown in the textbook). Can someone explain?
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    janet 9, i could be wrong but i think that the corpus lutenum only develops after ovulation because the follicle develops into it after the egg has gone. so progesterone is released after ovulation.
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    (Original post by skygirl999)
    Hi again all
    I have been trying to plan a few essay questions, but I have gotton stuck on some as there appears to be very little to write about. I'm going to post them all and what I have written down for them, and then if you have any further ideas you can add to them?:

    1. Nitrogen
    -The nitrogen cycle
    - The effect of nitrogen fertilisers and eutrophication

    2. Transfers through organisms:
    - Energy transfers
    - Digestive system

    3. Importance of water
    - Respiration
    - Transpiration
    - Water potential and osmosis
    - Transport in a plant
    (I also know it is needed for photosynthesis, but I can't remember where it directly comes in?)

    4. Surface area
    - Gas exchange surfaces
    - Homeostasis

    5. Hydrogen
    - Hydrogen bonds - DNA

    6. Importance of plants
    - Photosynthesis
    - Deforestation and global warming
    - Producers and food chains
    - Crop yields

    7. Structure of proteins
    - Amino acids - translation
    - Structures - polypeptide chain, secondary, tertiary and quaternary structures.

    So if you have any more points on any of the above topics can you PLEASE post them? I'm struggling a bit here!

    hey this is just some ideas
    nitrogen:
    -important in DNA and Amino acids
    -fertilisers

    transfer of energy:
    -trophic levels and inefficiency though the levels (unit4)
    -action potentials
    -ATP is the intermediate energy transfer molecule
    - energy in chemiosmotic gradients in ETC, H+ runs though ATP synthase causes ATP to be made(Also the electron transport chain in general)

    water:
    in photosynthesis, water is broken in photolysis into H+ e- and O2, these H+ combines with NADP, e- is used in electron transport chain
    -water is wher life started
    -hydrolysis reactions breaking ATP and proteins apart
    -cystic fibrosis in lungs
    -polar so things can dissolve, allowing ions to be formed (plant roots)
    -hydrogen bonding, transpiration

    surface area:
    -Axon diameter effects speed of impulse
    -SA in leaf for max light absorbs
    -more proteins in higher surface area, e.g. chlorophyll on thylakoid membranes
    -SA:V ratio in temp control, heat loss and respiration
    -vasoconstriction/dilation

    Hydrogen:
    -Electron transport chain
    -photosynthesis
    -co enzymes in respiration, also glycolosis and the actions of NAD
    -hydrocarbons, (most organic molecules)
    -acidic conditions (caused by H+ ions), Hb in blood
    -hydrogen bonds also happen when proteins gain secondary structure

    sorry its not much but i hope this is any help and its not to late ahah x
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    Im abit unsure about gene therapy.

    How is the fragment of DNA transcrbed in the human cell if its succesfully inserted. Does it have promotor regions? Can transciption occur outside of the nucleous?
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    hiyaa guys,, if i look at the freexampapers, which unit from the old spec is most similar to unit 5...??
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    can someone please reassure me veryone on the this thread is amazingly clever
    because i thought i was well prepared after reading some of the stuff on here :\
    need an A in this ir no university for me
    for the synoptic essay ive just made plans for about 30 possible essay titles
    how much detail do we need to know about the uses of recombinant dna technology?..its really boring lol
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    (Original post by UCAS.LOVER)
    Can someone please clarify what the ATP actually does in relation to the myosin head during the sliding filament mechanism? Does it just provide the energy for filaments to slide or does it provide energy to break the actin-myosin cross bridge aswell? I'm using the text book, CGP revision guide and Heck Grammar notes - but none have given me a definitive answer. Cheers lads + gals.
    ATP is used to '****' the myosin head. when the ATP is hydrolysed it provides the energy for the myosin head to stretch out again and form a cross bridge, the ADP is releaced from the myosin head and this causes the Myosin head to change angle and so move the actin filiment along. another molecule of ATP binds to it and then the cycle continues, hope this is some help
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    (Original post by Destroyviruses)
    Im abit unsure about gene therapy.

    How is the fragment of DNA transcrbed in the human cell if its succesfully inserted. Does it have promotor regions? Can transciption occur outside of the nucleous?
    i dont understand your q
    i thought we just have to know for example an adenovirus will inject the normal cftr gene in to the dna of the epithelial cells ?
 
 
 
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