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Thread: HSC Biology Marathon 2017

  1. #26
    Member Mathew587's Avatar
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by pikachu975 View Post
    2009 HSC Q23

    A woman recently conceived Britain’s first baby guaranteed to be free
    from hereditary breast cancer. Doctors screened for an embryo that was
    free from a gene that can cause breast cancer.
    The screening was performed due to the long history of this form of
    cancer in the family and the fact that any daughter born with the gene
    would have a 50%–80% chance of developing breast cancer.

    Explain the possible impact of this reproductive technology on the genetic
    composition of the population. (2 marks)


    The answers just say "This reproductive technology" wouldn't you need to specify the technology? What's the reproductive technology here anyway...
    Well I'm pretty sure it's genetic screening. My answer would probs go like this:

    Genetic screening refers to the screening on embryonic DNA and can assist in identifying deformities and issues before birth. As a result, the parents can choose whether to continue the birth or to abort. This would result in less genetic variation leading to a more homogenous population but may also result in the deformity being eradicated from the population.
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    Re: HSC Biology Marathon 2017

    Looking at the marking guidelines, it says nothing about stating the technology;

    "Correctly relates widespread use of the reproductive technology to
    changes in the genetic composition of the population."

    So based on this and the wording of the question you're not expected to know the technology, just it's effects on the genetic composition of the population.

  3. #28
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by ShootingDuck View Post
    Looking at the marking guidelines, it says nothing about stating the technology;

    "Correctly relates widespread use of the reproductive technology to
    changes in the genetic composition of the population."

    So based on this and the wording of the question you're not expected to know the technology, just it's effects on the genetic composition of the population.
    Yeah but say you were in the exam, you'd probably think you had to name one, that's what I (and others) thought initially
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by pikachu975 View Post
    Yeah but say you were in the exam, you'd probably think you had to name one, that's what I (and others) thought initially
    That's understandable, i just looked at the marking guidelines to make sure I wasn't giving out the wrong information or if there was indeed a technology like that in the syllabus we're meant to know.

    If you guys don't mind checking, would this be an acceptable answer?

    "It would decrease the genetic variation in the population since embryos without specific genes are being chosen. This can lead to a decrease in inherited diseases as the genes associated with particular inherited diseases aren’t selected and removed from the population."

    Thank you in advance.

  5. #30
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by ShootingDuck View Post
    That's understandable, i just looked at the marking guidelines to make sure I wasn't giving out the wrong information or if there was indeed a technology like that in the syllabus we're meant to know.

    If you guys don't mind checking, would this be an acceptable answer?

    "It would decrease the genetic variation in the population since embryos without specific genes are being chosen. This can lead to a decrease in inherited diseases as the genes associated with particular inherited diseases aren’t selected and removed from the population."

    Thank you in advance.
    Looks good but maybe instead of saying "It" use "The reproductive technology" because one question in my exam the question said "Julie" and the teacher said he nearly took a mark off people for not putting her name in the answer. Also you could be specific and say "inherited diseases e.g. breast cancer" just to relate to the stimulus.
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    Re: HSC Biology Marathon 2017

    http://prntscr.com/gminxd

    What would we write for b? Also isn't it a dodgy question since not everyone would study 'wilting' as their plant adaptations...
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    Re: HSC Biology Marathon 2017

    http://prntscr.com/gminxd

    What would we write for b? Also isn't it a dodgy question since not everyone would study 'wilting' as their plant adaptations...
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    Re: HSC Biology Marathon 2017

    You talk about how the xylem carries waters and ions. So if they are thinner, more water and ions will ooze out i.e. through transpiration. This will result in less water and ions being passed to the leaves and the plant itself, resulting in the plant wilting. )
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by Mathew587 View Post
    You talk about how the xylem carries waters and ions. So if they are thinner, more water and ions will ooze out i.e. through transpiration. This will result in less water and ions being passed to the leaves and the plant itself, resulting in the plant wilting. )
    The answers for some reason talked about the xylem collapsing so no water can be transported it's weird
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by Mathew587 View Post
    You talk about how the xylem carries waters and ions. So if they are thinner, more water and ions will ooze out i.e. through transpiration. This will result in less water and ions being passed to the leaves and the plant itself, resulting in the plant wilting. )
    The answers for some reason talked about the xylem collapsing so no water can be transported it's weird
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by pikachu975 View Post
    The answers for some reason talked about the xylem collapsing so no water can be transported it's weird
    who knows... it's meant to be a sample answer anyways
    use the answer criteria instead. pretty sure i'd get 3 marks for that q cos thin walls would def result in increased water loss from transpiration.
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  12. #37
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by Mathew587 View Post
    who knows... it's meant to be a sample answer anyways
    use the answer criteria instead. pretty sure i'd get 3 marks for that q cos thin walls would def result in increased water loss from transpiration.
    Isn't transpiration in the leaves via evaporation
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by pikachu975 View Post
    Isn't transpiration in the leaves via evaporation
    i meant the loss of water through the stem
    "Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers."
    pretty sure that includes the stem
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    Re: HSC Biology Marathon 2017

    Quarantine measures exist to prevent the spread of disease into Australia

    Justify TWO measures that you would expect AQIS (the Australian Quarantine and Inspection Service) to take in response to the recent swine flu outbreak in Mexico and North America (4 marks)

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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by pikachu975 View Post
    The answers for some reason talked about the xylem collapsing so no water can be transported it's weird
    How does that work? How come if the walls of the Xylem are thinner, they collapse? Also, the transpiration cohesion adhesion theory is when water molecules from the leaves evaporate in which the cohesion force between the molecules will act like a train, dragging the liquid water molecule up from the plants body to the leaves to replace the evaporated water molecule. The adhesion force between the molecule and the wall (i guess) will just allow the water to stay in place without it falling back down to the roots or whatever.

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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by Snowflek View Post
    How does that work? How come if the walls of the Xylem are thinner, they collapse? Also, the transpiration cohesion adhesion theory is when water molecules from the leaves evaporate in which the cohesion force between the molecules will act like a train, dragging the liquid water molecule up from the plants body to the leaves to replace the evaporated water molecule. The adhesion force between the molecule and the wall (i guess) will just allow the water to stay in place without it falling back down to the roots or whatever.
    I think its the fact that if they're thinner, it wouldn't be able to support it's own weight, causing the xylem tube to "collapse." Also if the xylem tubes "collapse," it could block itself off. Therefore no or limited amount of water can go through its own xylem tubes, causing the plant to effectively wilt rather than only affecting the adhesion forces between the water molecules and the wall.
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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by ShootingDuck View Post
    Quarantine measures exist to prevent the spread of disease into Australia

    Justify TWO measures that you would expect AQIS (the Australian Quarantine and Inspection Service) to take in response to the recent swine flu outbreak in Mexico and North America (4 marks)
    - The AQIS could isolate individuals from Mexico and North America coming into the country for a certain incubation period to ensure they are free from swine flu. This would prevent its spread into Australia as it would be a good precautionary measure for any Mexican or North American, where the outbreak came from.
    - The AQIS could also check organic material, animals, and plants to check if the swine flu has transmitted to other things besides humans. If found to be infected, they would be isolated through quarantine at the borders until the disease has subsided, thereby preventing its spread.
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    Re: HSC Biology Marathon 2017

    Analyse the effect of high mutation rates of viruses on human health as well as the survival of the virus. 7 marks

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    Re: HSC Biology Marathon 2017

    Quote Originally Posted by budgetjackiechan View Post
    Analyse the effect of high mutation rates of viruses on human health as well as the survival of the virus. 7 marks
    This question is basically 2005 HSC Q27 slightly re-worded and without the background information given about the influenza virus. Anyway, I'll take a shot at answering the HSC question:

    27. The influenza virus has a high rate of mutation which can lead to changes of the viral
    surface antigens that contain protein. Analyse the impact of high mutation rates for this virus and the implications for
    human health (8 marks).
    - A viral pathogen such as the influenza virus is engulfed by a macrophage and it’s surface antigen is transported to a lymph node to be presented to a helper T cell. Here, the helper T cell ‘sensitises’ B cells to the pathogen. The B cells then clone and differentiate into plasma B cells and memory B cells. The plasma B cells manufacture antibodies which are specific to the virus, which then bind to the viral antigens and neutralise them, allowing cytotoxic T cells to directly destroy them. The role of the memory B cells is to respond rapidly in the event of a second infection by the same virus.
    - If this happens, they clone rapidly to make plasma B cells and the immune response (secondary response) is faster and of greater magnitude than the primary (first) response. This will generally prevent the host from suffering from the disease a second time.
    - However, with rapidly mutating viruses such as the influenza virus, the viral surface antigens would have changed to the point where the memory B cells don’t recognise it and don’t trigger the secondary immune response. Therefore the host experiences the virus’s symptoms once again while the mutated viral pathogen survives until the host's immune system initiates another primary response against it.
    - In today’s society most countries have a seasonal-flu vaccine, however since the influenza virus constantly mutates a new version has to be developed each year or so, an expensive process which can takes months. This time lag could be potentially deadly to overall human health if there were ever to be a severe influenza pandemic in which the virus spread rapidly around the world, since humans have little to no immune protection against new flu strains.
    Last edited by LADislav; 8 Oct 2017 at 2:55 PM.
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