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OCR Biology F214 Communication, Homeostasis and Energy Wed 25 Jan 2012

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    my predictions for the exam...compare and contrast type 1 and type 2 diabetes..something on endotherms and ectotherms..something on the kidneys- possibly ultrafiltration or loop of henle..definetly something on photosynthesis and repiration- maybe like an experimental question..some sort of maths question regarding the kidneys and some fill in the blanks..I have a feeling that maybe pregnancy question will come up
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    anyone know what the difference is between the frequency of contractions and the frequency of waves of excitation in the heart? Surely if the frequency of WoE's increases, so will the frequency of contractions?
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    (Original post by Salmaa!)
    anyone know what the difference is between the frequency of contractions and the frequency of waves of excitation in the heart? Surely if the frequency of WoE's increases, so will the frequency of contractions?
    contractions are when the ventricles contract to pump blood out of the heart
    waves of excitation are the impulses that cause the contractions

    so your right when you say that an increase in waves of excitation from the SAN to the AV nodes cause an increase in contractions of the walls of the ventricles
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    (Original post by undertaker1)
    contractions are when the ventricles contract to pump blood out of the body.
    waves of excitation are the impulses that cause the contractions

    so your right when you say that an increase in waves of excitation from the SAN to the AV nodes cause an increase in contractions of the walls of the ventricles
    you are awesome.

    thanks for your help.. again
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    Here are some notes on the Kidneys and Excretion for those who do not have the CGP book.

    One of the main functions of the kidney is to excrete waste products, e.g. urea produced by the liver. They also regulate the body's water content. Here's an overview of how they excrete waste products.
    1) Blood enters the kidney through the renal artery and then passes through capillaries in the cortex of the kidneys.
    2) As the blood passes through the capillaries, substances are filtered out of the blood and into long tubules that surround capillaries. This process is called Ultrafiltration.
    3) The filtered blood passes out of the kidney though the renal vein.

    Blood is Filtered at the Start of the Nephrons:
    The long tubules along with the bundle of capillaries where the blood is filtered are called nephrons, there's thousands of these in each kidney.
    1) Blood from the renal artery enters smaller arterioles in the cortex
    2) Each arteriole splits into a structure called the glomerulus - a bundle of capillaries in a cup-shaped structure called the bowman's capsule.
    3) This is where Ultrafiltration takes place
    4) The arteriole that takes blood into each glomerulus is called the afferent arteriole, and the arteriole that takes the filtered blood away from the glomerulus is called the efferent arteriole.
    5) The efferent arteriole is smaller in diameter than the afferent arteriole, so the blood in the glomerulus is under high pressure.
    6) The high blood pressure forces liquid and small molecules in the blood out of the capillary and into the renal capsule.
    7) The liquid an small molecules pass through three layers to get into the renal capsule and enter the nephron tubules - the capillary wall, a membrane called the basement membrane and the epithelium of the renal capsule. Larger molecules like proteins and blood cells can't pass through and stay in the blood.
    8) The liquid and small molecules, now called filtrate pass along the rest of the nephron and useful substances are reabsorbed along the way.
    9) Finally, the filtrate flows through the collecting duct and passes out of the kidney along the ureter.
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    I understand that during respiration, Red. FAD and Red.NAD both contribute their electrons to the ETC, and that Red.NAD contributes its protons for the electrochemical gradient, which is a source of potential energy to form ATP, and that Red. FAD contributes its protons to react with O2 (along with e-'s from ETC), to form H2O.

    Do the protons which take part in chemiosmosis also react with the O2 to form H2O? I don't think there is any mention in the purple OCR textbook of where the protons from chemiosmosis end up after they have flowed through ATP Synthase.



    Another question, regarding factors affecting photosynthesis. When CO2 levels become very high, and the stomata close as a stress response, is it because they are losing water through the stomata?
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    (Original post by Lalaa)
    that last question on respiration experiments
    Do we still need to know that stuff????
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    (Original post by --NWzD9--)
    I understand that during respiration, Red. FAD and Red.NAD both contribute their electrons to the ETC, and that Red.NAD contributes its protons for the electrochemical gradient, which is a source of potential energy to form ATP, and that Red. FAD contributes its protons to react with O2 (along with e-'s from ETC), to form H2O.

    Do the protons which take part in chemiosmosis also react with the O2 to form H2O? I don't think there is any mention in the purple OCR textbook of where the protons from chemiosmosis end up after they have flowed through ATP Synthase.



    Another question, regarding factors affecting photosynthesis. When CO2 levels become very high, and the stomata close as a stress response, is it because they are losing water through the stomata?
    Only read your last Q
    ---> yes ..a lot of transpiration occurs ..oh hang on thats not because of high level of Co2..its when temp is increased ..why would they lose water in high Co2 !!!
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    (Original post by arvin_infinity)
    Only read your last Q
    ---> yes ..a lot of transpiration occurs ..oh hang on thats not because of high level of Co2..its when temp is increased ..why would they lose water in high Co2 !!!
    At High co2 more stomata open..so rate of transpiration increases c:
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    (Original post by arvin_infinity)
    Only read your last Q
    ---> yes ..a lot of transpiration occurs ..oh hang on thats not because of high level of Co2..its when temp is increased ..why would they lose water in high Co2 !!!
    I may have worded it wrong, but what i meant was that as the CO2 levels of the atmosphere increased, and the CO2 uptake increased, this would mean that lots of stomata will be open for gaseous exchange. This would result in greater water loss from the stomata, and so as a stress response, they will close (unless they are getting enough water to compensate from the soil)
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    I've just looked through the syllabus and it said we need to be able to evaluate the experimental evidence for the theory of chemiosmosis Can anyone conclude what we actually need to know for this, because I'm looking through the OCR text book and it seems really jibberish and I'm not sure whether we need all the information in there about it. Thanks.
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    Can someone please explain the function of the sodium potassium pump in the proximal convoluted tubule please? I don't understand where the sodium ions get pumped to...very confused any help would be appreciated sooo much!
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    (Original post by katie.lou)
    Can someone please explain the function of the sodium potassium pump in the proximal convoluted tubule please? I don't understand where the sodium ions get pumped to...very confused any help would be appreciated sooo much!
    Basically, the mechanism is:
    - Na+/K+ pump, pumps Na+ out of cell lining proximal convoluted tubule to ensure sodium ion concentration in low in cells lining proximal convoluted tubule.
    - co transporter proteins transports amino acid or glucose molecule associated with a sodium ion into the cell lining the proximal convoluted tubule by faccilated diffusion.
    -The concentration of glucose and amino acids rise into the cells lining the proximal convoluted tubule and diffuse down their concentration gradient and out the other side of the cell, into the tissue fluid. They're then able to diffuse from the tissue fluid to the capillaries.

    Makes anymore sense?
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    (Original post by gemstar!)
    I've just looked through the syllabus and it said we need to be able to evaluate the experimental evidence for the theory of chemiosmosis Can anyone conclude what we actually need to know for this, because I'm looking through the OCR text book and it seems really jibberish and I'm not sure whether we need all the information in there about it. Thanks.

    The main theory is Peter Mitchell theory which is chemiosmosis theory
    He basically discovered that the hydrogen ions were all on one side of the membrane and therefore concluded that a ph/electrochemical gradient was present. So from that he suggested that the h ions would move down a gradient through the membrane to make ATP. He then suggested that they made that ATP by being attached to enzymes as they went through the membrane.

    The other evidence is just about rupturing parts of the mitochondria so they removed the outer membrane leaving a mitoblast (mitochondria without outer membrane) they then ruptured the inner membrane, this then allowed the release of the contents of the matrix this allowed identification of kerbs and link taking place in the matrix and that the matrix contains enzymes for respiration. And that electron transport chains are embedded in the inner mitochondrial membrane. These produced no ATP in the mitoblasts (as the inner membrane is removed) so they concluded inner mitochondrial membrane was involved. The ATP wasn't made if the mushroom stalked particles were removed from the inner mitochondrial. And ATP wasn't made when anti biotics blocked flow of protons.

    That's pretty much all you need to know I think if i do have parts wrong I apologise please correct.
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    (Original post by gemstar!)
    Basically, the mechanism is:
    - Na+/K+ pump, pumps Na+ out of cell lining proximal convoluted tubule to ensure sodium ion concentration in low in cells lining proximal convoluted tubule.
    - co transporter proteins transports amino acid or glucose molecule associated with a sodium ion into the cell lining the proximal convoluted tubule by faccilated diffusion.
    -The concentration of glucose and amino acids rise into the cells lining the proximal convoluted tubule and diffuse down their concentration gradient and out the other side of the cell, into the tissue fluid. They're then able to diffuse from the tissue fluid to the capillaries.

    Makes anymore sense?
    Definitely, thank you so much! Just couldn't grasp it, makes so much more sense when someone else explains it aha left all my revision far too late!
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    (Original post by katie.lou)
    Definitely, thank you so much! Just couldn't grasp it, makes so much more sense when someone else explains it aha left all my revision far too late!
    Don't worry about it! I only grasped that bit last night because the text book makes it so much more confusing than it really is! Eurggg, im dreading Wednesday -.-
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    if anyone wishes to do additional questions on the liver from the old spec, the paper is called 2805/05 mammalian physiology and behaviour
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    (Original post by undertaker1)
    if anyone wishes to do additional questions on the liver from the old spec, the paper is called 2805/05 mammalian physiology and behaviour
    Mate what was the oldest F214 paper?
    I can only find Jan 10?
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    Probably a really silly question, but what's the difference between thylakoids and lamellae?
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    Question regarding Examination question on page 32 of the Purple OCR textbook:

    Q. 5)a)i)
    My answer was:
    A = 3
    B = 2
    C = 1

    Mark scheme, which can be accessed from the CD, says:
    A = 1
    B = 3
    C = 2

    I am sure this is wrong, and that my answers should be correct? Correct me if I'm wrong please

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