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OCR Biology F214

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    Explain why there is an increase in the rate of photosynthesis when temperature increases to 20 - 25 degrees (2)
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    (Original post by ds4143)
    Explain why there is an increase in the rate of photosynthesis when temperature increases to 20 - 25 degrees (2)
    because when temperature increases the rate of particles increases and therefore more kinetic energy and also, the molecule binds more quickly with the enzyme to catalyse the reaction.
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    (Original post by otrivine)
    because when temperature increases the rate of particles increases and therefore more kinetic energy and also, the molecule binds more quickly with the enzyme to catalyse the reaction.
    Perfect!! 2/2
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    (Original post by ds4143)
    Perfect!! 2/2
    thanks

    describe where the light dependent stage occurs and name the process which takes place (2)
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    Occurs in the thylakoid membrane. The process is non-cyclic and cyclic photophosphorylation
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    (Original post by ds4143)
    Occurs in the thylakoid membrane. The process is non-cyclic and cyclic photophosphorylation
    yes correct but i was thinking more of process of photophosphroylation ???????
    my turn
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    Ohh right, I guess its still right though because photophosphorylation is divided into cyclic and non-cyclic Well you were probably looking for that one answer XD

    okay umm

    Explain how reabsoprtion in the proximal convoluted tubule occurs? (5)
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    (Original post by ds4143)
    Ohh right, I guess its still right though because photophosphorylation is divided into cyclic and non-cyclic Well you were probably looking for that one answer XD

    okay umm

    Explain how reabsoprtion in the proximal convoluted tubule occurs?
    No but still you will get your marks dont worry
    ok

    Reabsorption occurs if there is lack of water level (especially when dehydrated) aand how it happens is that the sodium and potassium ions are actively pumped or transported into the proximal covulted tubules and has sodium and potassium ions and moves in by diffusion. How it occurs is by osmoreceptors and also the walls become more permeable so easy diffusion of ions(water)
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    (Original post by otrivine)
    No but still you will get your marks dont worry
    ok

    Reabsorption occurs if there is lack of water level (especially when dehydrated) aand how it happens is that the sodium and potassium ions are actively pumped or transported into the proximal covulted tubules and has sodium and potassium ions and moves in by diffusion. How it occurs is by osmoreceptors and also the walls become more permeable so easy diffusion of ions(water)
    Ooo you got pretty muddled up there! The 'walls becoming more permeable' stuff happens in the collecting duct, at the end of the nephron. The proximal convoluted tubule is the first wavy part of the nephron (just underneath the bowmans capsule)

    From the beginning in the efferent and afferent aterioles, the blood has a very low water potential as it exits though the afferent atriole...because all the water was pushed out into the bowmans capsule. So the fluid in the capsule has a HIGH water potential.

    Okay so as the fluid moves along the nephron, the first part it reaches is the proximal convoluted tubule. The cells lining the proximal convoluted tubule are specialised for readsorption, for not only water, but also amino acids, glucose, and sodium. It has microvilli, for large surface area to volume ratio. The water in the nephorn needs to be reabsorbed back into the blood. Water moves into the cell by osmosis, and then out the other side of the cell where the low water potential capillaries are. Also glucose and amino acids are transported into the cell along with sodium by facilitated diffusion. The other side of the cells have specialised Na and K pumps, K is pumped in, sodium is actively transported out into the blood, this creates low potential of sodium inside the cell, causing sodium to move in from the nephron. As the glucose and amino acid conc rises inside the cell, it also moves out of the other side of the cell into the capillaries.

    I know all this is too long for 5 marks, but I explained it abit more further so it could help you understand it..I hope it did help >.<!
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    (Original post by ds4143)
    Ooo you got pretty muddled up there! The 'walls becoming more permeable' stuff happens in the collecting duct, at the end of the nephron. The proximal convoluted tubule is the first wavy part of the nephron (just underneath the bowmans capsule)

    From the beginning in the efferent and afferent aterioles, the blood has a very low water potential as it exits though the afferent atriole...because all the water was pushed out into the bowmans capsule. So the fluid in the capsule has a HIGH water potential.

    Okay so as the fluid moves along the nephron, the first part it reaches is the proximal convoluted tubule. The cells lining the proximal convoluted tubule are specialised for readsorption, for not only water, but also amino acids, glucose, and sodium. It has microvilli, for large surface area to volume ratio. The water in the nephorn needs to be reabsorbed back into the blood. Water moves into the cell by osmosis, and then out the other side of the cell where the low water potential capillaries are. Also glucose and amino acids are transported into the cell along with sodium by facilitated diffusion. The other side of the cells have specialised Na and K pumps, K is pumped in, sodium is actively transported out into the blood, this creates low potential of sodium inside the cell, causing sodium to move in from the nephron. As the glucose and amino acid conc rises inside the cell, it also moves out of the other side of the cell into the capillaries.

    I know all this is too long for 5 marks, but I explained it abit more further so it could help you understand it..I hope it did help >.<!
    was it 5 marks i thought 2 marks thats why i said it a bit brief ?sorry and thanks i got it
    Describe what is meant by kuppfer cells(2)
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    (Original post by otrivine)
    was it 5 marks i thought 2 marks thats why i said it a bit brief ?sorry and thanks i got it
    Describe what is meant by kuppfer cells(2)
    Yeh 5marks, my fault though I forgot to put the marks in, so I edited it in

    Kuppfer cells are macrophages, they move around in the sinusoid of hepactocyte lobule cells breaking down old red blood cells into bilirubin.
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    I'm quite nervous about this, got 50/90 in January because I had bad exam technique - couldn't do the applied questions or suggests.
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    Osmoregularity:
    -the water potential in the blood is monitored by osmo-receptors in the hypothalamus,
    -when water potential is low, osmoereceptors lose water by osmosis, which causes them to shrink and stimulate neurosecretory cells in the hypothalamus,
    -the neurosecretory cells are specialised neurones that release ADH, it flows down the axon into posterior pituitary gland, when they are stimulated they send action potentials down their axons and release ADH,
    -which enters the blood,
    -it's slowly broken down,

    -the walls of the collecting duct responds to the level of ADH in the blood,
    -cells in the wall have membrane bound receptors or ADH. The ADH binds to them and causes a chain of enzyme-controlled reactions inside the cells, which inserts vesicles containing water-permeable channels, into the surace membrane,
    -the move ADH in blood, the more aquaporins, the more permeable to water,
    -if there is less ADH, the plasma membrane olds towards to create new vesicles that remove aquaporins,

    Control of Heart rate in humans:
    -The heart muscle is myogenic,
    -it has its own pacemaker called SAN,
    -it's supplied by nerves from the medulla oblongata of the brain, which connect to SAN-they don't initiate contraction, but they affect the frequency of the contractions,
    -action potentials sent down the accelerator nerve increase the heart rate, action potentials sent down the vagus nerve decrease the heart rate,
    -it responds to adrenaline in the blood,


    -when we exercise, muscles produce CO2 some of this reacts with the water in the blood plama and reduces its pH, Which is detected by chemoreceptors in the carotid arteries, the aorta and the brain, -the chemoreceptors send impulses to the cardiovascular centre, which increases the heart rate,
    -when we stop exercising the concentration of CO2 in the blood falls, the activity in the accelerator pathway falls, heart rate declines,




    kidney failure:
    -body is unable to remove excess water and certain waste products from the blood, which includes urea and certain salts,
    dyalisis:
    -removes wastes, excess fluid+salt combined,
    kidney transplants:
    -freedom, less limited diet, feels better, better quality of life,
    -infection, risk of surgery, need immunorepressants for rest of kidney life,


    urine sample
    pregnancy testing:
    -hCG secreted when pregnant,
    -special antibodies only bind to hCG,
    -hCG attaches to antibody tagged with a blue bead,
    -hCG antibody complex moves up the strip until it sticks to a band of immobilised enzymes,

    anabolic steroids:
    -gas chromatography, sample is vapourised and eventually comes out of gas is absorbed by the lining,
    -which is analysed to create chromatogram,


    Diabetes Mellitus:
    type I diabetes:
    -insulin dependent,
    -autoimmune response, bodys own immune system attacks the b-cells and destroys them,
    -body is no loner able to manufacture sufficient insulin and can't store excess glucose as glucagon,

    type II diabetes:
    -non insulin-dependent,
    -can still produce insulin,
    -as people their responsiveness to insulin declines,
    -the specific receptors on the surface of the liver and muscle cells decline and the cells lose their ability to respond to the insulin,

    treatment:
    -type II diabetes is usually treated by careful monitoring and control of the diet, match carbohydrate intake and use,
    -this may eventually be supplemented by insulin injections or use of other drugs which slows the absorption of glucose from the digestive system,

    -type I diabetes is treated using insulin injections the blood glucose concentration must be monitored and the correct dose of insulin must be administered to ensure that the glucose concentration remains fairly stable,
    -stem cells-pancreas of adult mice,
    -exact copy, less chance of developing tolerance or rejection, cheaper, more moral,
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    (Original post by AndyHoughton)
    I'm quite nervous about this, got 50/90 in January because I had bad exam technique - couldn't do the applied questions or suggests.
    What was your bad exam technique? Maybe I can learn from it if you dont mind ^.^

    I absolutely hate application questions, in unit5 that whole paper was like full of it -.- Hopefully I can do better in this eam though
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    (Original post by ds4143)
    Yeh 5marks, my fault though I forgot to put the marks in, so I edited it in

    Kuppfer cells are macrophages, they move around in the sinusoid of hepactocyte lobule cells breaking down old red blood cells into bilirubin.
    correct 1/2 only thing you forgot was the word recycle
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    oohh okay so it breaks down old RBC and recycles it?

    Okay heres a big one... Explain every single stage in the Calvin cycle 10marks
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    (Original post by ds4143)
    oohh okay so it breaks down old RBC and recycles it?

    Okay heres a big one... Explain every single stage in the Calvin cycle 10marks
    yes correct
    Oh my god this is long ok
    co2 diffuses into stomata and into the stroma where the light independent reaction takes place, The co2 binds with the enzyme and forms a compound known as RUBP and this is catalysed by an enzyme called rubisco. then the is turned into a different compound called GP which is then carboxylated and turns into TP. Every 5 out of the 6 molecules are recylced and are used for different processes. The recelyced are turned into 6 carbon molecule which can be isomerised into another 6 carbon compound called hexose. Also, is used for making fatty acids and glycerol. also can be turned into glucose which will help to provide energy. This process of calvin cylce occurs in the stroma and is in the light independent stage
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    (Original post by otrivine)
    yes correct
    Oh my god this is long ok
    co2 diffuses into stomata and into the stroma where the light independent reaction takes place, The co2 binds with the enzyme and forms a compound known as RUBP and this is catalysed by an enzyme called rubisco. then the is turned into a different compound called GP which is then carboxylated and turns into TP. Every 5 out of the 6 molecules are recylced and are used for different processes. The recelyced are turned into 6 carbon molecule which can be isomerised into another 6 carbon compound called hexose. Also, is used for making fatty acids and glycerol. also can be turned into glucose which will help to provide energy. This process of calvin cylce occurs in the stroma and is in the light independent stage
    LOL well that was perfect!! Except GP is reduced and phosphorylated, not carboxylated 10/10 still though coz you mentioned more than 10 points (Y) >=]
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    (Original post by ds4143)
    LOL well that was perfect!! Except GP is reduced and phosphorylated, not carboxylated 10/10 still though coz you mentioned more than 10 points (Y) >=]
    thanks
    describe photophorylation (5)

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Updated: September 20, 2013
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