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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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    (Original post by TlanTlan)
    God dammit the menstrual cycle is such a giant pain, apart from that everything else in this unit seems reasonably straightforward except for the sheer volume of information needed to be learned for DNA technology.
    :teehee: you made a Bio funny.
    Yeah I hate the menstrual cycle and blood glucose level control stuff as well.
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    (Original post by Destroyviruses)
    use my mindmap
    That is...horrifying.
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    (Original post by tehsponge)
    That is...horrifying.
    Why :C ?
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    (Original post by Destroyviruses)
    use my mindmap
    Thankyou that is so helpful !
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    can anyone help me out on the following questions:
    What is the importance of maintaining a constant blood pH in relation to enzyme activity?
    what is the importance of maintaining a constant blood glucose concentration in terms of energy transfer and water potential of blood?
    what is the effect of adrenaline on glycogen breakdown and synthesis?
    what is the second messenger model of adrenaline and glucagon action?
    what are the main differences between tRNA and mRNA?

    this is all from the spec, but i wouldn't be able to answer them if they came up on the exam... :/
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    (Original post by Destroyviruses)
    Why :C ?
    Sooo many lines and boxes
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    (Original post by vickidougal)
    Thankyou that is so helpful !
    Yay! Your welcome. I wanted someone other than me to find it helpful. Be mindful though , I've missed some topics that I'm pretty confident about. So use the specs on AQAs site.
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    (Original post by tehsponge)
    Sooo many lines and boxes
    The secret is to ignore them all and focus on one box at a time! Or if you are feeling really clever try to link it to another box!

    I'm normally never as productive so to me it looked beautiful when i finished!!
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    (Original post by vickidougal)
    can anyone help me out on the following questions:
    What is the importance of maintaining a constant blood pH in relation to enzyme activity?
    what is the importance of maintaining a constant blood glucose concentration in terms of energy transfer and water potential of blood?
    what is the effect of adrenaline on glycogen breakdown and synthesis?
    what is the second messenger model of adrenaline and glucagon action?
    what are the main differences between tRNA and mRNA?

    this is all from the spec, but i wouldn't be able to answer them if they came up on the exam... :/
    Note form okay , i dont like words.

    Q1 : -enzymes have a narrow optimum pH range
    -pH change could break hydrogen bonds on enzyme
    -change tertiary structure of active site
    -enzymes can not form complex , cannot catalyse reactions,cannot function
    Q2 : Low blood glucose:- respiration cannot occur ,energy cannot be transfered to ATP
    High blood glucose: Water potential of blood decreases. Water moves into blood by osmosis. Dehydration/

    Q3 Adrenalin : Stimulates glycogen breakdown to glucose (in liver) by secondary messenger.
    Inhibits formation of glycogen from glucose (in liver) by secondary messenger.


    Q4 Adrenalin binds to receptor on cell> stimulates enzyme>enzyme causes production of second messenger (cAMP) >second messenger produces required change.

    Q5 tRNA is clover shaped, mRNA is single helix
    tRNA is alittle more stable than mRNA
    tRNA brings amino acids has particular anticodons., mRNA contains anticodons(holds the genetic code)
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    (Original post by vickidougal)
    can anyone help me out on the following questions:
    What is the importance of maintaining a constant blood pH in relation to enzyme activity?
    Deviation from the normal pH breaks bonds in the enzymes -----> tertiary structure changes -----> active site no longer complementary to the enzyme's substrate.
    what is the importance of maintaining a constant blood glucose concentration in terms of energy transfer and water potential of blood?
    In terms of water potential, glucose lowers the W.P. of the blood if its conc is too high. Water leaves the cells, causing them to shrivel and dehydrate. The reverse happens if blood glucose is too low. In terms of energy transfer, it's important that blood glucose doesn't fall too low or too high - otherwise cells won't have a large enough source of energy.
    what is the effect of adrenaline on glycogen breakdown and synthesis?
    Remember that adrenaline has the same action as glucagon ie it stimulates an increase in blood glucose level.
    what is the second messenger model of adrenaline and glucagon action?
    this animation goes into a bit more detail than you need, but it helps to clarify what's taking place in the cell: http://highered.mcgraw-hill.com/site...ger__camp.html
    what are the main differences between tRNA and mRNA?
    tRNA is a shorter, clover-shaped molecule, whereas mRNA is longer and linear. Of course there's the functtional differences as well - one is used to bring together amino acids; the other transfers the genetic code from the nucleus to the ribosomes.
    this is all from the spec, but i wouldn't be able to answer them if they came up on the exam... :/
    Hope this helps
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    I'm so relieved to see that other people are struggling as much as me! I agree, there is a hell of a lot to remember. And there's such a lack of information as to what to expect from the essay question, so I think we're all gonna be pretty worried about that one!
    Am I the only one who find the whole Action potential stuff difficult to remember? It's pretty simple but it's just so dull I really struggle to remember it well enough. I need to get a B in this exam so fingers crossed it will all pay off!

    Good luck everyone
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    I find the Gene technology the hardest topic like restriction mapping, recombinant stuff, vectors etc
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    HERE ARE ALL THE PAST ESSAY Q'S (OUR TEACHER GAVE US THESE)


    1. The different ways in which organisms use ATP
    2. How the structure of cells is related to their function.
    3. How bacteria affect human lives.
    4. The biological importance of water
    5. The structure and functions of carbohydrates
    6. Cycles in biology
    7. How carbon dioxide gets from a respiring cell to the lumen of an
    alveolus in the lungs.
    8. How an amino acid gets from protein in a person’s food to becoming
    part of a human protein in that person.
    9. The transfer of energy between different organisms and between
    these organisms and their environment.
    10. Ways in which different species of organisms differ from each other
    11. Negative feedback and its importance in biology
    12. Condensation and hydrolysis and their importance in biology
    13. Inorganic ions include those of sodium, phosphorous and hydrogen.
    Describe how these and other inorganic ions are used in living
    14. Bacteria affect the lives of humans and other organisms in many ways. Apart from causing disease, describe how bacteria may affect the lives of other organisms.
    15. Polymers have different structures. They also have different functions .Describe how the structures of different polymers are related to their functions.
    16. Describe how nitrogen-containing substances are taken into, and metabolised in, animals and plants.
    17. Carbon dioxide in organisms and ecosystems.
    18. Why the offspring produced by the same parents are different in appearance.
    19. Hydrogen bonds and their importance in living organisms
    20. How nitrogen-containing substances are made available to and are used by living organisms
    21. The uses of water in living organisms
    22. The transfer of energy within and between organisms
    23. Carbon dioxide may affect organisms directly or indirectly. Describe and explain these effects.
    24. The causes of disease in humans.
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    (Original post by bethalex)
    Anything really as I'm really struggling with knowing what to put in the essays, so would you mind sending my the titles you have and the different things to put in each of them. Would it be easier if i just gave you my email?

    Thank you
    HERE YOU GO

    1. The different ways in which organisms use ATP
    2. How the structure of cells is related to their function.
    3. How bacteria affect human lives.
    4. The biological importance of water
    5. The structure and functions of carbohydrates
    6. Cycles in biology
    7. How carbon dioxide gets from a respiring cell to the lumen of an
    alveolus in the lungs.
    8. How an amino acid gets from protein in a person’s food to becoming
    part of a human protein in that person.
    9. The transfer of energy between different organisms and between
    these organisms and their environment.
    10. Ways in which different species of organisms differ from each other
    11. Negative feedback and its importance in biology
    12. Condensation and hydrolysis and their importance in biology
    13. Inorganic ions include those of sodium, phosphorous and hydrogen.
    Describe how these and other inorganic ions are used in living
    14. Bacteria affect the lives of humans and other organisms in many ways. Apart from causing disease, describe how bacteria may affect the lives of other organisms.
    15. Polymers have different structures. They also have different functions .Describe how the structures of different polymers are related to their functions.
    16. Describe how nitrogen-containing substances are taken into, and metabolised in, animals and plants.
    17. Carbon dioxide in organisms and ecosystems.
    18. Why the offspring produced by the same parents are different in appearance.
    19. Hydrogen bonds and their importance in living organisms
    20. How nitrogen-containing substances are made available to and are used by living organisms
    21. The uses of water in living organisms
    22. The transfer of energy within and between organisms
    23. Carbon dioxide may affect organisms directly or indirectly. Describe and explain these effects.
    24. The causes of disease in humans.
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    i hate the fact that there is only one paper to learn from
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    i especially hate the dna stuff more bothered about chem 5 atm
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    we used the only past paper for our mock at school.. so tried the spec paper (which teacher said was crap)
    only to find he was right.. the questions are stupid! i would just use exam style qus from book to revise tbh!
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    (Original post by Charlottehall)
    What are people's predictions for the essay? It's the main thing worrying me.
    I'm gutted it was disease last year because I think that would have been a really good one to write about because sooo much of the course is on it and plenty of unit 5.
    thankyouuu
    im **** at essays but in my mock i got a C on the essay and an A overall... so if you dont do too well you can still make it up on the exam!
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    (Original post by emmaaa65)
    would someone please be able to look over this synoptic essay i did and maybe give me a rough mark out of 25? i dont have anyone to mark them as im on study leave and cant get into school to hand them into teachers so i would really appreciate anyones help
    its a really rubbish one thats barely synoptic and took about 45mins including the plan

    Receptors and their role in coordination

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    Receptors allow an organism to respond to a stimulus, which could potentially be harmful, therefore increasing the chances of survival. Organisms with better adapted responses will have a selection pressure favouring them and will therefore be more likely to survive. There are many different types of receptors in organisms, controlling both the nervous system and the hormonal system. Receptors involved in the nervous system can either be linked to the autonomic or the voluntary system. This essay will discuss the many uses of receptors and how they are important to living organisms.

    Receptors respond to stimuli. Specific receptors will only respond to certain stimuli. In the nervous system receptors respond by sending nerve impulses down sensory neurones until they reach the CNS. One example of a receptor that does this is the Pacinian corpuscle, which only responds to mechanical pressure. The receptor consists of the ending of a sensory neurone, surrounded by layers of connective tissue. When a stimulus-mechanical pressure – is applied, it changes the shape of the axon membrane. This pressure also changes the shape of the stretch mediated sodium ion channels, causing the membrane to be more permeable to sodium ions. This causes an influx of sodium ions which reverses the potential difference across the membrane, depolarising it. If the stimulus exceeds the threshold value, a generator potential will be created that is large enough to initiate an action potential which then travels down the neurone as a nerve impulse. In this way receptors act as transducers, converting the energy of a stimulus into a message that the CNS can understand.
    Receptors are involved in reflex arcs which are rapid responses to harmful stimuli. A reflex arc is involuntary and involves a coordinator such as the spinal cord, ensuring rapid impulses, as the information does not have to be coordinated by the brain which would otherwise be overloaded with unnecessary information. This prevents harm to an organism therefore increases chances of survival.

    Simple responses to stimuli that involve receptors are Taxes, Kineses and tropisms. A taxis for example is a simple response that occurs due to a directional stimulus. Woodlice for example will respond to the directional stimulus of light by moving into darkness. Photoreceptors allow the woodlice to do this, preventing the woodlice from drying out and therefore increasing chances of survival. Tropisms affect plants and involve responses to directional stimuli such as light or gravity. Plants however cannot control responses by the nervous system therefore respond to stimuli via the hormonal system using chemicals called growth factors e.g. IAA. When a positive phototropism occurs the plant will grow towards light, as the growth factor IAA will travel down the shaded side of the shoot, causing that side to elongate and bend towards the light. This maximises photosynthesis and therefore increases chances of survival.

    Receptors in larger organisms are involved in controlling the functions of organs and certain processes. Chemoreceptors and baroreceptors in the carotid arteries/aorta respond to changes in the blood. Chemoreceptors for example respond to changes in pH (due to levels of carbon dioxide) if the pH is lower than the set point (due to high conc. of CO2) chemoreceptors will respond by sending impulses to the centre in the medulla oblongata that increases heart rate. The medulla will then send impulses down the sympathetic pathway connecting to the SAN, causing more electrical activity to be stimulated, therefore increasing heart rate (which removes excess CO2 as blood will circulate more rapidly) and returning the blood pH back to normal. This ensures that the CO2 level in the blood remains constant and at a safe level.

    Photoreceptors in the retina respond to stimuli in the form of light. There are two different types of photoreceptor; rod cells and cone cells. Many rod cells are connected to one bipolar cell (retinal convergence), therefore the threshold value needed to create an action potential is exceeded at lower light intensity. This means that rod cells only produce images on black and white and have low visual acuity. Cone cells however are each attached to an individual bipolar cell, therefore light of higher intensity is needed to overcome the threshold value. This means that cone cells respond only to high intensity light therefore can produce coloured images. As they are attached to individual bipolar cells, cone cells have high visual acuity. The type and number of photoreceptors in the retina is different for different organisms, adapting them to their environment for better survival.

    As well as nervous control, receptors are also involves in hormonal control. Glycoprotein receptors for example are situated on target cells and have a structure that is specific and complementary to a particular hormone. Glucagon is released from the a-cells of the islets of Langerhans in the pancreas and binds to receptors on liver cells (target cells). This hormone receptor complex formed activated an enzyme inside the cell that stimulates the conversion of ATP into cyclic AMP. The hormone glucagon therefore acts as a first messenger whilst the cyclic AMP acts as a second messenger. Cyclic AMP stimulates a number of chemical reactions that results in the desired response (Glycogenolysis and Gluconeogenesis) which in this case is to increase the blood glucose level. this is an example of negative feedback as the blood glucose level is returned to normal, therefore illustrating how receptors play a key role in homeostasis.

    Receptors are also involved in the immune system of an organism. In cell mediated immunity T-cells have receptors on their cell surface membrane that are specific and enable detection of any foreign material. These receptors therefore allow the body to respond to any harmful material such as bacteria or viruses. On binding to the foreign material the T-cells initiate an immune response involving B-cells and antibodies in order to destroy the pathogen and hence increase the chances of survival of the organism.

    Receptors play important roles in homeostasis and response to harmful stimuli. They can be involved in either voluntary or involuntary nervous systems or even in hormonal systems and therefore increase the chances of survival.


    i had alot more stuff in my plan such as control of body temperature etc but i ran out of time lol
    I think this is a pretty good essay, you get in a lot of knowledge and you'd probably get the relevance, breadth and quality of language marks. I'd say its 14/15 for the knowledge, maybe just add something about oestrogen receptors forming the transcription initiation complex to link receptors to DNA. Otherwise it's really good It's one of those questions where all the knowledge is from like only 1 unit.
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    (Original post by salman s)
    I think this is a pretty good essay, you get in a lot of knowledge and you'd probably get the relevance, breadth and quality of language marks. I'd say its 14/15 for the knowledge, maybe just add something about oestrogen receptors forming the transcription initiation complex to link receptors to DNA. Otherwise it's really good It's one of those questions where all the knowledge is from like only 1 unit.
    I like your sig
 
 
 
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