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Edexcel A2 Biology Unit 5 (6BIO5) - 22/06/2011- OFFICIAL THREAD ! watch

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    Um, if anyone has done the specimen paper.
    In reference to question 7(article part) of the paper, do you reckon it will be the same layout in our paper? With a longer small essay-ish question at the end?
    I think the Topic 7 and 8 stuff is pretty much sorted in terms of understanding and answering questions. Im really scared about this article...:woo:
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    (Original post by dynamikal)
    Um, if anyone has done the specimen paper.
    In reference to question 7(article part) of the paper, do you reckon it will be the same layout in our paper? With a longer small essay-ish question at the end?
    I think the Topic 7 and 8 stuff is pretty much sorted in terms of understanding and answering questions. Im really scared about this article...:woo:
    Yeh I do.
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    Welp, time to go practice some of these possible questions
    Cheeeeeyahs.
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    Guys, when are chemoreceptors used and when are baroreceptors used? I'm a little bit confused between control of breathing, control of heart rate and homeostasis.

    In homeostasis are chemoreceptors/baroreceptors used? Or is it just thermoreceptors/hypothalamus that detect the changes?

    Also, when are the sympathetic and parasympathetic nerves involved?
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    (Original post by skotch)
    Link reaction and Krebs cycle are definitely different!

    The link reaction converts pyruvate to acetyl coenzyme A through the loss of CO2 and I think H+ as well, which is different to the Krebs cycle which involves the formation of an unstable 6C compound and its subsequent degradation forming NAD/FAD/substrate level ATP.
    The link reaction isn't regarded as a stage on it's own ... I know I'm right.
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    I'm going to do a big review of Topics 7 and 8. Then work past papers. Then deal with the article.
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    Can someone provide a link to specimen paper please
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    (Original post by _joshb_)
    o2 isn't produced during aerobic respiration..?

    soory!! i ment the same amount of co2 is produced as o2 is absorbed!
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    (Original post by skotch)
    Guys, when are chemoreceptors used and when are baroreceptors used? I'm a little bit confused between control of breathing, control of heart rate and homeostasis.

    In homeostasis are chemoreceptors/baroreceptors used? Or is it just thermoreceptors/hypothalamus that detect the changes?

    Also, when are the sympathetic and parasympathetic nerves involved?
    We had a really confusing conversation about this in the chatroom thing, and I'm still confused. As far as I know:

    heart rate: blood pressure change detected by baroreceptors in neck --> medulla slows/speeds heart via vagus/sympathetic

    Ventillation rate: change in pH due to Co2 in blood detected by chemoreceptors in carotid artery and stretch receptors (whatever the hell they are) --> medulla sends impulses to diaphragm/intercostals, increasing/decreasing breathing rate accordingly

    Body temp: rise in core body temp detected by thermoreceptors --> hypothalamus sends impulses to sweat glands

    please someone correct me if I'm wrong
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    (Original post by Doughboy)
    The link reaction isn't regarded as a stage on it's own ... I know I'm right.
    if you consider the edexcel green book (concept) they dont even mention the 'link reaction' , though they do show the step just above the krebs cycle diagram. So even if it isn't considered as a separate stage, it still is not a part of the krebs cycle as acetylCoA ENTERS the Krebs cycle. :yep:
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    nyone using other chatrooms????????
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    (Original post by skotch)
    Guys, when are chemoreceptors used and when are baroreceptors used? I'm a little bit confused between control of breathing, control of heart rate and homeostasis.

    In homeostasis are chemoreceptors/baroreceptors used? Or is it just thermoreceptors/hypothalamus that detect the changes?

    Also, when are the sympathetic and parasympathetic nerves involved?
    Chemoreceptors (carotid arteries and aortic arch) detect changes in carbon dioxide level so hence pH (through dissocaition of hydrogen carbonate ~ H2CO3) If pH of blood falls (more acidic) the receptors will send impulses to the respiratiory centre in the medulla to send impulses along sympathetic nerves (accelerator) to increase breathing rate (more frequent contractions by stimulating intercostal and diaphram).

    Heart rate also increased by high CO2 levels and high lactate in blood; more impulses sent along sympathetic nerves to stimulate SAN; increased heart rate increases the venous return to the heart hence a rise in stroke volume; cardiac output rises.

    A higher cardiac output = higher blood pressure; detected by baroreceptors in aortic arch, carotid etc; inhibit impusles to CVC; inhibit impulses to SAN = reduced heart rate.

    Remember sympathetic = fight or flight responce whereas;
    parasympathetic = rest and digest
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    Anyone got a link to the latest Unit 5 paper and mark scheme. Much appreciated
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    (Original post by Mr van der WAALs)
    Heart rate also increased by high CO2 levels and high lactate in blood; more impulses sent along sympathetic nerves to stimulate SAN; increased heart rate increases the venous return to the heart hence a rise in stroke volume; cardiac output rises.
    Is this detected via pH by chemoreceptors?

    (Original post by Mr van der WAALs)
    A higher cardiac output = higher blood pressure; detected by baroreceptors in aortic arch, carotid etc; inhibit impusles to CVC; inhibit impulses to SAN = reduced heart rate.
    Are there any receptors in the neck? Or are they all in the carotid artery?

    Also do you know what a 'stretch receptor' is?
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    (Original post by skotch)
    Guys, when are chemoreceptors used and when are baroreceptors used? I'm a little bit confused between control of breathing, control of heart rate and homeostasis.

    In homeostasis are chemoreceptors/baroreceptors used? Or is it just thermoreceptors/hypothalamus that detect the changes?

    Also, when are the sympathetic and parasympathetic nerves involved?
    all receptors are invovled after all all aspects need to be controlled
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    Does any one have a method for the 3 core practicals?
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    I'm stuck on the article! I get everything except for the noradrenaline bit in the 'Stressed out' section, it says more noradrenaline is synthesized with repeated stress as a coping mechanism but shouldn't it be the other way around because the neurons are getting habituated? Also what exactly does noradrenaline do in the coping of stress? Thanks in advance for any help!
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    (Original post by _joshb_)
    Is this detected via pH by chemoreceptors?


    Are there any receptors in the neck? Or are they all in the carotid artery?

    Also do you know what a 'stretch receptor' is?

    stretch receptors are in the lungs and involved with medulla, inspiratory/expiratory centres and the intercostal and diaphragm muscles.
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    http://qchat.rizon.net/

    BI05

    Previous room was unreliable..
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    (Original post by HyperNova)
    http://qchat.rizon.net/

    BI05

    Previous room was unreliable..

    wat do u mean unreliable
    wats the point
    u cud just join in with the other people in 6BIO5
 
 
 
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