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

  • View Poll Results: Are you resitting this unit?
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    I remember for the last Unit 4 exam, someone posted Sir George Monoux Biology qyestions + answers (which I found helpful), does anyone have them for this unit (5) please?
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    can some1 please attach AQA BIO5 jan 2010 and 2011 QP and MS please?

    much appreciated :P
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    (Original post by kingsmod1)
    can some1 please attach AQA BIO5 jan 2010 and 2011 QP and MS please?

    much appreciated :P

    There is no January papers !

    AQA only put these papers out in July
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    (Original post by Mazii)
    There is no January papers !

    AQA only put these papers out in July
    but some1 must hve them, they always do

    can any1 help me on skpye on bio 5, there is so much to remember, yes u must practice but u need tyo remember basics too much lol
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    (Original post by kingsmod1)
    but some1 must hve them, they always do

    can any1 help me on skpye on bio 5, there is so much to remember, yes u must practice but u need tyo remember basics too much lol
    Its not about not owning them; they dont make papers for Jan units. BIOL5 is only made for June exams. Its only for Chemistry that you get Unit5 papers in Jan. So theres only 2 papers for Biol5 you can practice with: the specimen one and June 10
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    is anyone else finding the homeostasis section quite hard?
    i thought i would have found this section quite easy tbh, but going over past exam questions and stuff makes me realise how hard blood glucose control and temperature regualtion is.... is anyone else finding it difficult?
    i cant seem to get my head around glycogenolysis, glucogenesis and gluconeogensis?!?! if those are even correct!! lol
    eurghh this exam is going to be hell
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    Wahhh, sat down properly this morning to start revising this unit.. and there's blummin' 6 pages of the spec! SIX!! Thank god this is my last exam.. going to need all the time I can get.
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    (Original post by emmaaa65)
    is anyone else finding the homeostasis section quite hard?
    i thought i would have found this section quite easy tbh, but going over past exam questions and stuff makes me realise how hard blood glucose control and temperature regualtion is.... is anyone else finding it difficult?
    i cant seem to get my head around glycogenolysis, glucogenesis and gluconeogensis?!?! if those are even correct!! lol
    eurghh this exam is going to be hell
    Are you using the nelson thornes book? Its pretty good for this topic

    I did my notes for homeostasis on a powerpoint presentation, I can upload it if you want. It might not be of much help...

    Remember:
    Lysis is splitting
    Genesis is formation (birth)
    Neo is new
    Glyco and gluco = glucose
    Gluconeogenesis is the making( formation) of new (neo) glucose (gluco).
    Glycogenoslysis is the splitting (lysis) of glyocgen.

    Hope this hasn't made you more confused. But yeah, remembering the meaning of the terms seems to work for me.
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    (Original post by Eloades11)
    I have revised all the topics, although I cannot remember the lines and zones in the sarcomere. I know nothing about the menstrual cycle because I missed the 1 lesson we spent on it, and we have not been taught anything about cystic fibrosis :/

    Going well so far!
    The sacromere, here's how I remember it:

    I-Band is the space inbetween the two myosin filaments.

    Therefore the A-Band is the other, which is the myosin plus where it crosses over the actin.

    And Cystic Fibrosis isn't too difficult. Its caused by a mutant recessive allele that codes for a ion channel protein. This causes the ion channel for chloride ions to not function correctly on the membranes of epithelial cells. Without the chloride ions diffusing out of the cells, water cannot follow, meaning the mucus outside the cell becomes thick and sticky.

    It causes sperm ducts and pancreatic ducts to become blocked, and obviously breathing difficulties and increased risk of disease.

    Hope this helps
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    (Original post by INeedToRevise)
    Are you using the nelson thornes book? Its pretty good for this topic

    I did my notes for homeostasis on a powerpoint presentation, I can upload it if you want. It might not be of much help...

    Remember:
    Lysis is splitting
    Genesis is formation (birth)
    Neo is new
    Glyco and gluco = glucose
    Gluconeogenesis is the making( formation) of new (neo) glucose (gluco).
    Glycogenoslysis is the splitting (lysis) of glyocgen.

    Hope this hasn't made you more confused. But yeah, remembering the meaning of the terms seems to work for me.
    oh yes that would be brilliant if you can upload it! im usually alright with biology revision im just finding it hard to get my head around this topic, seeing as there is so much stuff to learn! :mad:
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    How does homeostasis and negative feedback control the level of glucose in the blood?


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    When there is an increase in blood glucose concentration
    An increase in blood glucose levels is detected by the Bcells of the islets of Langerhans in the pancreas. This stimulates the Bcells to secrete insulin directly into the blood plasma, where it is carried to the target cells of the body. Liver cells are the main target cells for insulin (where Glycogenesis occurs), however insulin does affect all the body cells. To decrease the level of blood glucose back to the set point, insulin binds to glucose protein channels on cell-surface membranes. This changes the tertiary structure of the protein channels, causing them to open which allows glucose molecules to diffuse into the cells. Insulin also increases the number of glucose protein channels on the cell surface membranes which again increases the influx of glucose into cells. This increase in permeability to glucose decreases the amount of glucose in the blood. Insulin also increases the rate of conversion of glucose into glycogen (Glycogenesis) which takes place in liver cells and again decreases the concentration of glucose in the blood. Insulin also increases the respiration rate of cells therefore more glucose is used up during Glycolysis, hence decreasing the amount of glucose in the blood. Insulin therefore uses negative feedback to return the blood glucose level back to the set point.

    When there is a decrease in blood glucose concentration
    A decrease in blood glucose levels is detected by the acells of the islet of Langerhans in the pancreas. This low level of glucose stimulates the acells to secrete the hormone glucagon directly into the blood plasma. Glucagon travels in the blood plasma to the target cells, which in this case are only the liver cells. Glucagon binds to receptors on the liver cells to form a hormone-receptor complex. Glucagon works by using a mechanism called the second messenger model. Glucagon acts as the first messenger and binds to receptors on liver cells and activates an enzyme inside the cell which causes the conversion of ATP into cyclic AMP, which acts as the second messenger. Cyclic AMP then stimulates a chain of reactions which results in the response, in this case the response is the conversion of glycogen into glucose (Glycogenolysis). By stimulating the conversion of glycogen into glucose, glucagon increases the level of glucose in the blood. Glucagon also stimulates the production of glucose from amino acids and glycerol, called Gluconeogenesis, which again increases the amount of glucose in the blood, returning it to the set level.
    Another hormone, adrenaline, also responds to a low level of glucose in the blood. The adrenal glands release adrenaline into the blood plasma and by using the second messenger mechanism adrenaline stimulates the conversion of glycogen into glucose (Glycogenolysis) which increases the blood glucose concentration meaning it is more available for respiration of muscle cells. Adrenaline also inhibits the conversion of glucose into glycogen (Glycogenesis) therefore again increasing the blood glucose concentration.

    These hormones work antagonistically to maintain the blood glucose concentration therefore causing fluctuations around the set point. It is essential that blood glucose levels remain constant for respiration and to maintain water potential. Very low concentrations of glucose result in hypoglycaemia, whilst very high concentrations in blood glucose result in hyperglycaemia.
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    How does homeostasis and negative feedback regulate body temperature in endotherms?

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    Increase in environmental temperature
    An increase in temperature is detected by the thermoreceptors in the skin, which sends nerve impulses to the heat loss centre of the hypothalamus. The hypothalamus also contains thermoreceptors which detect the change in temperature of the blood. The hypothalamus responds to this increase in temperature by activating processes through the autonomic nervous system from the heat loss centre. By using negative feedback, the heat loss centre activates processes such as vasodilation, sweating and lowering of body hairs. Vasodilation occurs when the arterioles near the skin dilate whilst the shunt and connective vessels constrict, forcing warm blood to flow near the surface of the skin, hence losing heat as it does so. An increase in sweating also results in a loss of heat as heat energy is required for the evaporation of sweat, therefore when sweat evaporates the skin is cooled. The lowering of body hair is brought about when pilo-erector muscles relax, therefore the less still air is trapped next to the skin, decreasing the thickness of the insulating layer therefore less heat is conserved. These processes are controlled by negative feedback therefore return the body temperature back to the set point.

    Decrease in environmental temperature
    A decrease in environmental temperature is detected by the thermoreceptors in the skin, which send nerve impulses to the heat gain centre in the hypothalamus. The thermoreceptors in the hypothalamus also detect the change in body temperature as a decrease in blood temperature will stimulate the heat gain centre. The heat gain centre will therefore send impulses along the autonomic nervous system, using negative feedback to activate processes which will return the body temperature back to the set point. These processes such as shivering, raising of body hairs, vasoconstriction and an increase in metabolic activity will decrease the amount of heat lost and increase the amount of heat generated, thus increasing the body temperature back to the set point. Impulses are sent to the muscles to increase involuntary contraction which increases the respiration rate of the muscles as more ATP will be needed, therefore increasing the amount of metabolic heat produced. The raising of body hairs is brought about when pilo-erector muscles contract, causing the hairs to stand upright, therefore trapping a thicker layer of still air next to the skin surface, which acts as a good insulator, therefore conserving heat. Vasoconstriction occurs when the arterioles constrict whilst the shunt vessels and connective vessels dilate, meaning less warm blood is able to pass next to the skin surface, therefore reducing heat loss. These processes help to conserve heat energy therefore bringing body temperature back to the set point by negative feedback.
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    hey im stuck on plants atm, basically i know nitrate are used to make proteins in plants with glucose. Yet if there is a lack of nitrates that means there is a lack of protein being made, so what happens to the glucose that cant be converted to protein?
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    (Original post by danneh150)
    The sacromere, here's how I remember it:

    I-Band is the space inbetween the two myosin filaments.

    Therefore the A-Band is the other, which is the myosin plus where it crosses over the actin.

    And Cystic Fibrosis isn't too difficult. Its caused by a mutant recessive allele that codes for a ion channel protein. This causes the ion channel for chloride ions to not function correctly on the membranes of epithelial cells. Without the chloride ions diffusing out of the cells, water cannot follow, meaning the mucus outside the cell becomes thick and sticky.

    It causes sperm ducts and pancreatic ducts to become blocked, and obviously breathing difficulties and increased risk of disease.

    Hope this helps
    Thanks a lot, and by assuming the sperm ducts have an increased risk of being blocked then there's an increased risk of infertility?
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    Anyone else nervous about the Synoptic essay?
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    I'm not looking forward to this exam in general. I need an A overall, and so need around a B in this paper. But it seems a mammoth task right now!
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    (Original post by bethalex)
    i've barely done anything so far, feel really bad bout it, i'm kinda freaking out about the essay aswell, does anyone have a big list of mark schemes for all the different titles there has been, if so it would be really helpful to me, thank you

    i don't think we got taught anything about cystic fibrosis either:/
    I think Cystic Fibrosis was an example for a use of Gene Therapy rather than just learning about the actual condition.
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    (Original post by (Online))
    I'm not looking forward to this exam in general. I need an A overall, and so need around a B in this paper. But it seems a mammoth task right now!
    You'll only need 60% in this exam to get an A, that works as some encouragement, but try not to think "Oh, well, I can get 60% and get an A, I don't need to revise as much as I thought!"

    I have written 1 essay, and I got it marked at a C grade by my teacher. I haven't written an essay since -.- my teacher gave me no useful feedback and I don't know how to make it better, so why write another essay if it's just going to be the same as my last?

    Does anyone object to me writing up my essay on here so I could receive some constructive criticism?
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    Going to start posting my exam-time condenced notes for people if they want them, probably will start later today or tomorrow .

    I've covered about half of the syllabus and memorised it, how is everyone else doing? I hope to have everything more or less memorised by Wednesday so I can start doing past paper questions and essay practice for the last two weeks.
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    Made a load of A3 revision posters for this unit and chem 5. You realise how much there is to know when biology takes up 2 walls...
 
 
 
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