Hey there! Sign in to join this conversationNew here? Join for free

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

  • View Poll Results: Are you resitting this unit?
    YES!
    12.91%
    NO!
    87.09%

    Offline

    2
    ReputationRep:
    (Original post by Cyanohydrin)
    Adrenalin.

    I was wondering. If we are asked about the initial cause of the depolarising stiumulus that causes the voltage gated sodium channels to open ....and then an action potential....

    what would you say?

    'they are the result of the receptor to the stiumulus - for example some chemicals trigger chemoreceptors to open chemical gated sodium channels, likewise pressure gated receptors (i.e. pacinian corpsucle) etc etc ...?'
    Yeah, except the heart which is myogenic so self stimulated. Everything else ,its the lovely brain.
    Offline

    0
    ReputationRep:
    does anyone have the examiner's report for the bio unit 5 june 2010 paper?
    Offline

    0
    ReputationRep:
    (Original post by kingsmod1)
    guys for chap 13 i dont understand it says fsh stimulates oestrogen to be prodcued but then oestrogen inhibits fsh?

    for up to day 10 oestrogen stimulaes rise in fsh, wtf though it inhibits it?????



    MANY THANKSSSSSSSSSSSSS
    its positive and negative feedback. Oestrogen starts with negative feedback inhibiting FSH and LH until it reaches a threashold then its positive feedback to stimulate the follicle for ovulation. just depends upon the amount of oestrogen whether its positive or negative feedback. hope this helps, total nightmare us females
    Offline

    2
    ReputationRep:
    what do you think gonna come up!?

    For synoptic bit=
    1.Surely we get something about enzymes
    2.Protein structure

    Unit 5=
    1.Body temp (describe-explain)
    2.Menstrual cycle
    3.PCR
    4.Mutation
    5.Cancer( supresser and proto oncogen)

    Add/edit this list so we can have a bit of prediction for what is more likely to come up
    Offline

    2
    ReputationRep:
    (Original post by mariiahgac)
    help hahaha

    Can someone help me with this?

    One of my biology books say that "high blood pressure is detected by baroreceptors, then impulses are sent to the medulla oblongata, sending impulses along parasympathetic newurons, which secrete acetylecholine, which then binds to receptors on the SAN"

    Whereas my other biology book says that " high blood pressure is detected by baroreceptors, then impulses are sent to the center in the medulla oblongata that decreases heart rate, which then increases the frequency of impulses to the SAN via the parasympathetic nervous system"

    What should I say in my exam then?? :/
    They are saying the same thing! chose the shorter one! Oh but mention that barreceptors are in carotid arteries you get a mark for that.
    Offline

    13
    ReputationRep:
    (Original post by Destroyviruses)
    Yeah, except the heart which is myogenic so self stimulated. Everything else ,its the lovely brain.
    Would you call the opening of pressure gated sodium channels say as the effector?
    Offline

    0
    ReputationRep:
    would someone briefly outline positive feedback? read 2 diff books but i still don't get it. any helpful links?
    thanks!
    Offline

    0
    ReputationRep:
    (Original post by Destroyviruses)
    I think, tahts what it means by "eye piece scale"
    if you read the examiners report on that question its hilarious as i think most people have written it as we were taugth in AS but they wanted all the stuff about graticule !!
    Offline

    2
    ReputationRep:
    (Original post by denisewoosey)
    if you read the examiners report on that question its hilarious as i think most people have written it as we were taugth in AS but they wanted all the stuff about graticule !!
    I've never even SEEN the word graticle in any of my textbooks!
    Offline

    2
    ReputationRep:
    (Original post by won-derer)
    does anyone have the examiner's report for the bio unit 5 june 2010 paper?
    http://web.aqa.org.uk/qual/pdf/AQA-B...-WRE-JUN10.PDF
    Offline

    13
    ReputationRep:
    (Original post by teddyWS)
    would someone briefly outline positive feedback? read 2 diff books but i still don't get it. any helpful links?
    thanks!
    mechanisms that enhance the output created by a stimulus - they result in even greater depatures from the original level

    take temperature as an example..

    if the temperature went 37 --> 38

    positive feedback would see it go to 39, 40, 41, 42 etc

    likewise if it went 37 ---> 36

    you would see - 35, 34, 33, 32, 31 etc
    Offline

    2
    ReputationRep:
    (Original post by denisewoosey)
    if you read the examiners report on that question its hilarious as i think most people have written it as we were taugth in AS but they wanted all the stuff about graticule !!
    what the hell is a graticle!
    Offline

    0
    ReputationRep:
    (Original post by Destroyviruses)
    They are saying the same thing! chose the shorter one! Oh but mention that barreceptors are in carotid arteries you get a mark for that.
    wouldnt acetylcholine increase the heart rate tho? :/ its an excitatory neurotransmitter
    Offline

    0
    ReputationRep:
    (Original post by Destroyviruses)
    what the hell is a graticle!
    That ruler in a microscope eyepiece
    Offline

    2
    ReputationRep:
    (Original post by teddyWS)
    would someone briefly outline positive feedback? read 2 diff books but i still don't get it. any helpful links?
    thanks!
    A stimulus causes a change in the set-point, but instead of the body trying to bring it back to normal, the stimulus causes a further move away from set point. (not sure if this explanation is clear enough!)

    e.g. during depolarisation, opening of sodium channels causes sodium ions to flood into the cell, which then leads to opening of adjacent sodium channels.

    eg. breakdown of temperature control during a fever

    eg. production of oxytocin, which causes dilation of the cervix during labour - is on a positive feeback loop, so contractions become faster and quicker.
    Offline

    0
    ReputationRep:
    (Original post by Cyanohydrin)
    mechanisms that enhance the output created by a stimulus - they result in even greater depatures from the original level

    take temperature as an example..

    if the temperature went 37 --> 38

    positive feedback would see it go to 39, 40, 41, 42 etc

    likewise if it went 37 ---> 36

    you would see - 35, 34, 33, 32, 31 etc
    (Original post by flowerscat)
    A stimulus causes a change in the set-point, but instead of the body trying to bring it back to normal, the stimulus causes a further move away from set point. (not sure if this explanation is clear enough!)

    e.g. during depolarisation, opening of sodium channels causes sodium ions to flood into the cell, which then leads to opening of adjacent sodium channels.

    eg. breakdown of temperature control during a fever

    eg. production of oxytocin, which causes dilation of the cervix during labour - is on a positive feeback loop, so contractions become faster and quicker.


    aww thank you!
    Offline

    3
    ReputationRep:
    (Original post by mariiahgac)
    wouldnt acetylcholine increase the heart rate tho? :/ its an excitatory neurotransmitter
    If there's anything that increases heart rate, it's definately adrenaline, which binds to SAN receptors, increasing heart rate, so returning xxxx back to normal levels.

    The opposite is ACh, which only for heart rate as I've found, is secreted, binds to SAN receptors, and slows down heart rate.

    But don't get mixed up with Acetylcholine being transmitted accross a cholinergic synapse, binding to sodium channels/receptors, causing them to open, allowing the influx of Na+.

    (ACh is a shorthand way of writing Acetylcholine)
    Offline

    0
    ReputationRep:
    (Original post by janet9)
    If there's anything that increases heart rate, it's definately adrenaline, which binds to SAN receptors, increasing heart rate, so returning xxxx back to normal levels.

    The opposite is ACh, which only for heart rate as I've found, is secreted, binds to SAN receptors, and slows down heart rate.

    But don't get mixed up with Acetylcholine being transmitted accross a cholinergic synapse, binding to sodium channels/receptors, causing them to open, allowing the influx of Na+.

    (ACh is a shorthand way of writing Acetylcholine!
    Mmmmm just got confused why ACh would decrease heart rate rather than increasing it
    Offline

    2
    ReputationRep:
    (Original post by mariiahgac)
    wouldnt acetylcholine increase the heart rate tho? :/ its an excitatory neurotransmitter
    Acetylcholine is the neurotransmitter used by the parasympathetic nervous system. It binds to muscarinic receptors and helps in regulation of parasympathetic functions.

    Edit: I did not mean ACh is used exclusively in parasympathetic nervous system. It is also used at other sites. But it is the neurotransmitter used by parasympathetic nervous system. In contrast the sympathetic nervous system used adrenaline and noradrenaline.
    Offline

    2
    ReputationRep:
    (Original post by mariiahgac)
    Mmmmm just got confused why ACh would decrease heart rate rather than increasing it
    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:
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Has a teacher ever helped you cheat?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Write a reply...
    Reply
    Hide
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.