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    The specification says 'Explain the fate of lactate after a period of anaerobic respiration in animals.' I am assuming this means that we don't need to know about alcohol fermentation in yeast cells?
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    (Original post by Nilie)
    Yes, you need to know what they are, the symptoms and how to detect them from an ECG trace.
    x
    Thank youuuuu!!

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    (Original post by Nilie)
    in Glycolysis, when 2x3C compounds get converted into pyruvate, the book says the reaction uses 4ADP+2Pi to make 4ATP. How can you make 4ATP molecules from just 2 phosphates???

    And also, for a non chemistry person , does 1NAD require 2 Hydrogens to become reduced (is reducedNAD=NAD+2H)??

    Thanksssss

    xx
    Originally you used 2 ATP molecules to phosphorylate the glucose molecule to make it reactive. The phosphate groups In the two 3 C molecule that was to be oxidised to make pyruvate, is combined two other Pi and 4 ADP to thus make 4 ATP through substrate level phosphorylation.. However, there is only a net gain of 2 ATP from the glycolysis step due to you having used 2 ATP in the first step.
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    (Original post by Nilie)
    in Glycolysis, when 2x3C compounds get converted into pyruvate, the book says the reaction uses 4ADP+2Pi to make 4ATP. How can you make 4ATP molecules from just 2 phosphates???

    And also, for a non chemistry person , does 1NAD require 2 Hydrogens to become reduced (is reducedNAD=NAD+2H)??

    Thanksssss

    xx
    During the first stage of glycolysis, the ATP involved in making the 2 3C compound from glucose donates a Pi to the 3C compounds, making them phosphorylated. When the 2 3C compounds become converted to two pyruvate molecules, the two phosphates from the 3C compounds are donated to 2 of the ADP molecules, hence the reason why only 2 other Pi are needed to make four ATP molecules.

    And yes, it does.
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    (Original post by Hdizzle)
    Originally you used 2 ATP molecules to phosphorylate the glucose molecule to make it reactive. The phosphate groups In the two 3 C molecule that was to be oxidised to make pyruvate, is combined two other Pi and 4 ADP to thus make 4 ATP through substrate level phosphorylation.. However, there is only a net gain of 2 ATP from the glycolysis step due to you having used 2 ATP in the first step.

    thanks!)
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    (Original post by Brad0440)
    During the first stage of glycolysis, the ATP involved in making the 2 3C compound from glucose donates a Pi to the 3C compounds, making them phosphorylated. When the 2 3C compounds become converted to two pyruvate molecules, the two phosphates from the 3C compounds are donated to 2 of the ADP molecules, hence the reason why only 2 other Pi are needed to make four ATP molecules.

    And yes, it does.
    thanksxx
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    as you are so good at respiration, can somebody also explain why do you need O2?? i don't understand the point "if O2 is not present, electrons will not be accepted so NAD and FAD will finish" O_o thats what my notes say/.....
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    (Original post by Nilie)
    as you are so good at respiration, can somebody also explain why do you need O2?? i don't understand the point "if O2 is not present, electrons will not be accepted so NAD and FAD will finish" O_o thats what my notes say/.....
    O2 is the final electron acceptor in the electron transport chain. If there is no O2, reduced NAD and reduced FAD do not lose their electrons and hydrogen to become NAD and FAD, so less NAD and FAD are formed.
    Since there is less NAD and FAD, glycolysis and the Kreb's cycle are also affected.
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    (Original post by SKK94)
    O2 is the final electron acceptor in the electron transport chain. If there is no O2, reduced NAD and reduced FAD do not lose their electrons and hydrogen to become NAD and FAD, so less NAD and FAD are formed.
    Since there is less NAD and FAD, glycolysis and the Kreb's cycle are also affected.
    thats the part i don't get. Why wouldn't they lose them? O2 accepts the already "free" electrons, it does not "take" them from rNAD, does it?

    sorry for being such a pain
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    In anaerobic conditions, the concentration of H+ rises and NADH and FADH2. But why does the concentration of NAD fall? Is it because NADH donates its H+ is reused in the Krebs cycle?
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    More unit 5 questions:

    Name the two antagonistic muscles that work to control the size of the eye, and state whether they contract to dilate or constrict the pupil. (2)
    Spoiler:
    Show

    - {Radial} muscles AND contract to {dilate/widen/eq} the pupil
    - {Circular} muscles AND contract to {contract/constrict/make smaller/eq} to pupil


    State two functions of the hypothalamus. (2)
    Spoiler:
    Show

    - Controls hunger/thirst
    - Controls sleep
    - Monitors/controls body/skin temperature
    - Secretes hormones itself
    - Controls hormonal secretion by the pituitary gland


    *Describe and explain how an action potential is generated in the bipolar cell in the retina. (6)
    Spoiler:
    Show

    One mark is available for points written in a logical order, quality of written communication and the correct spelling of terms in italics

    - Light causes rhodopsin to break down
    - Rhodopsin breaks down into opsin and retinal
    - Reference to opsin indirectly causing the {hydrolysis} of a molecule on the {cation/sodium/eq} channel
    - Reference to the closure of the {cation/sodium/eq} channel
    - Reference to sodium being pumped out of the {inner segment} causing {Hyperpolarisation} of the rod cell
    - Idea of no action potential/impulse being generated
    - (Therefore) there is no neurotransmitter released at the synapse
    - The synapse between the rod cell and bipolar cell is {inhibitory} AND as no neurotransmitter is being released an action potential is generated in the bipolar cell
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    (Original post by Nilie)
    thats the part i don't get. Why wouldn't they lose them? O2 accepts the already "free" electrons, it does not "take" them from rNAD, does it?

    sorry for being such a pain
    It's essential for electrons to be able to pass along the electron carriers through the redox reactions, to provide the energy required to pump H+ ions into the intermembrane space. Now when the electrons reach the end of the carrier chain they will combine with H+ and O2 to form water. Without any O2 present the electron carrier chains become saturated and can therefore not take anymore electrons from the reduced coenzymes therefore the electron transport chain stops functioning, and oxidative phosphorylation can no longer take place.
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    (Original post by Brad0440)
    More unit 5 questions:

    Name the two antagonistic muscles that work to control the size of the eye, and state whether they contract to dilate or constrict the pupil. (2)
    Spoiler:
    Show

    - {Radial} muscles AND contract to {dilate/widen/eq} the pupil
    - {Circular} muscles AND contract to {contract/constrict/make smaller/eq} to pupil


    State two functions of the hypothalamus. (2)
    Spoiler:
    Show

    - Controls hunger/thirst
    - Controls sleep
    - Monitors/controls body/skin temperature
    - Secretes hormones itself
    - Controls hormonal secretion by the pituitary gland


    *Describe and explain how an action potential is generated in the bipolar cell in the retina. (6)
    Spoiler:
    Show

    One mark is available for points written in a logical order, quality of written communication and the correct spelling of terms in italics

    - Light causes rhodopsin to break down
    - Rhodopsin breaks down into opsin and retinal
    - Reference to opsin indirectly causing the {hydrolysis} of a molecule on the {cation/sodium/eq} channel
    - Reference to the closure of the {cation/sodium/eq} channel
    - Reference to sodium being pumped out of the {inner segment} causing {Hyperpolarisation} of the rod cell
    - Idea of no action potential/impulse being generated
    - (Therefore) there is no neurotransmitter released at the synapse
    - The synapse between the rod cell and bipolar cell is {inhibitory} AND as no neurotransmitter is being released an action potential is generated in the bipolar cell
    thanks a lot <3
    are these questions from past papers??
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    (Original post by Hdizzle)
    It's essential for electrons to be able to pass along the electron carriers through the redox reactions, to provide the energy required to pump H+ ions into the intermembrane space. Now when the electrons reach the end of the carrier chain they will combine with H+ and O2 to form water. Without any O2 present the electron carrier chains become saturated and can therefore not take anymore electrons from the reduced coenzymes therefore the electron transport chain stops functioning, and oxidative phosphorylation can no longer take place.
    that makes sense now, thanks a lot ^___________^
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    (Original post by Nilie)
    are these questions from past papers??
    I haven't taken them from past papers, but there might be questions like them in the past papers.
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    (Original post by Brad0440)
    I haven't taken them from past papers, but there might be questions like them in the past papers.
    if they came up in the exam, that would be fantastic..your questions make so much sense and are testing the biology, not how well you can overcome tricks)
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    (Original post by Lastminutepanic)
    The specification says 'Explain the fate of lactate after a period of anaerobic respiration in animals.' I am assuming this means that we don't need to know about alcohol fermentation in yeast cells?
    hopefully, not. At least, my teacher did not spend any time on it, so i assume its not going to be tested
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    Could someone define 'negative feedback' please and an example of it in action in homeostasis??
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    (Original post by JaayBiology)
    Could someone define 'negative feedback' please and an example of it in action in homeostasis??
    Negative feedback is returning to the norm value in responce to deviating from it.

    Example of thermoregulation:

    Body temperature rises
    --> thermoreceptors on skin surface detect this
    --> the send an impulse to the temperature control center in the hypothalamus (more specifically - the heat loss center)
    --> the TCC sends an impulse to the effectors
    --> temperature falls back to normal

    Effectors can be: relaxing hair erector muscles, sweat glands secreting sweat, metabolic reactions occuring at a slower rate.
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    ^ and the dilation of arterioles and the inhibition of the dilation of shunts, so that blood flows more closely to the skin's surface so more heat lost through evaporation or as radiation.
 
 
 
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