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Thread: HSC Biology Marathon 2015

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    Senior Member Fiction's Avatar
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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by DepressedPenguino View Post
    Nice man band 6 responses (imo) right there . By the way, what does it mean by artificial blood is cheaper to synthesis compared to using real blood? why is there a cost for using real blood?
    haha thanks )

    The textbook(s) I'm using - where I get my notes and such from, don't specifically mention this, however they do state that apparently getting blood cross-matched and tested for infectious diseases and such is resource heavy. So I'm assuming the cost of production of artificial blood is lower than getting real blood sorted, tested and/or separated into their various components etc.

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    Re: HSC Biology Marathon 2015

    Hey guys just a quick question, how do you guys study for bio cos I put shit loads of effort and I'm only get around the 70's. If it matters, I go to a rank 40ish school

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    Senior Member Fiction's Avatar
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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by BlueGas View Post
    "Never trust anything on the internet" - Abraham Lincoln

    Question: Explain some of the chemical changes that occur in the environment with one named example.
    Chemical changes in the environment can occur as a result of changes in salinity levels, pH or the introduction of a new chemical to the environment. These changes then act as a selection pressures upon an individual organism or species, eventually resulting in a change in the species's population as better adapted individuals survive longer than those who are not as well adapted to these selective pressures.

    An example of the latter is mosquitos and DDT. When DDT was first introduced as an insectcide to kill mosquitos, a large population of individual mosquitos within the allocated region, died as a result. Therefore low concentrations of DDT was effective. However, as time passed, those individuals who were initially well-adapted to the chemicals were able to survive the initial spraying, reproduce and potentially pass on their more advantageous genetic information to their offsprings. Those who were not resistant, and hence died out, were not able to pass on their disadvantageous genes to their offspring. This meant that the population of mosquitos resistent to DDT grew in size therefore subsequent sprayings of DDT needed much higher concentrations than the initial spraying. That is, DDT had become less effective.

    Hence the gene pool of mosquitos had changed due to a change in the chemical environment, that is the introduction of DDT as an insecticide where DDT acted as a selection pressure.

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    Senior Member Fiction's Avatar
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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by duhdevitt View Post
    Hey guys just a quick question, how do you guys study for bio cos I put shit loads of effort and I'm only get around the 70's. If it matters, I go to a rank 40ish school
    That's me, but with a different school rank lol

    For some reason, I keep bombing out during actual tests.

  5. #30
    Exalted Member BlueGas's Avatar
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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by duhdevitt View Post
    Hey guys just a quick question, how do you guys study for bio cos I put shit loads of effort and I'm only get around the 70's. If it matters, I go to a rank 40ish school
    By effort, what do you mean? Memorising? Understanding? If I have an upcoming test, I'd just memorise the whole module, but not all in one go, I'll memorise a chapter fully until I move onto the next one. Once you're done with a chapter, ask maybe your brother or sister to ask you questions.

    You should memorise the chapter fully to a point that if your brother/sister is looking at a page in the chapter, you'll know what he/she is looking at and you'll answer him/her before he/she even asks the question. I'm saying this because when my brother asks me questions, he goes in order from the first page to the last, and I'll already know what he's going to be asking me and it helps me memorise better. This is just how I study, hopefully you find a way of studying which is better for you and will make your marks skyrocket.
    Last edited by BlueGas; 4 Apr 2015 at 12:19 PM.

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by Fiction View Post
    haha thanks )

    The textbook(s) I'm using - where I get my notes and such from, don't specifically mention this, however they do state that apparently getting blood cross-matched and tested for infectious diseases and such is resource heavy. So I'm assuming the cost of production of artificial blood is lower than getting real blood sorted, tested and/or separated into their various components etc.
    Yeah same with the notes that i found.. only mentions that artifical blood cost more than using donated blood but doesn't provide any further justification. However, after reading your reasoning, i think you could be right with the high cost of dobated coming from getting it sorted into its blood types and testing it to see if it carries any pathogens. Thanks again

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by DepressedPenguino View Post
    Yeah same with the notes that i found.. only mentions that artifical blood cost more than using donated blood but doesn't provide any further justification. However, after reading your reasoning, i think you could be right with the high cost of dobated coming from getting it sorted into its blood types and testing it to see if it carries any pathogens. Thanks again
    Nw

    Evaluate the following statement:
    Evolution is both supported and not supported by paleontological evidence. (5 marks)

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    Re: HSC Biology Marathon 2015

    Why do freshwater fish actively absorb salts if they gain a lot of water by osmosis? Wouldn't salt absorption attract even more water, causing it to burst?

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by duhdevitt View Post
    Hey guys just a quick question, how do you guys study for bio cos I put shit loads of effort and I'm only get around the 70's. If it matters, I go to a rank 40ish school
    Videos are also really good to work with (look on Youtube). If the theory is visually presented, you'll more likely understand and remember it.
    Queenroot and hawkrider like this.

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by Fiction View Post
    Nw

    Evaluate the following statement:
    Evolution is both supported and not supported by paleontological evidence. (5 marks)
    The theory of evolution is supported by Paleontology, which is the study of fossils. A fossil record shows the sequence of the earliest of life to today's present organisms, this supports the theory of evolution and suggests that there is evidence of change in organisms. An example is horses:

    - Early horses were small animals, with four toes and a small check span.
    - Modern horses are large horses, with one toe and a large check span.

    The fossil record of horses shows that horses evolved from being small, having more than one toe and a small check span to horses that are large, have one toe and a large check span.


    I don't know the answer to why evolution is not supported by paleontological evidence, I haven't come across such a question before.
    Last edited by BlueGas; 4 Apr 2015 at 4:54 PM.

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    Re: HSC Biology Marathon 2015

    Can someone confirm whether phagocytosis occurs in the lymph nodes?

    From what i have read so far, only B and T lymphocytes are located in the lymph nodes and not phagocytes (which can perform phagocytosis).

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by DepressedPenguino View Post
    Can someone confirm whether phagocytosis occurs in the lymph nodes?

    From what i have read so far, only B and T lymphocytes are located in the lymph nodes and not phagocytes (which can perform phagocytosis).
    Well from my notes:
    Lymph nodes store lymphocytes and macrophages. Macrophages are developed from monocytes which are a type of phagocytes. So I'm pretty sure phagocytosis occurs in lymph nodes as they store phagocytes. I'm not 100% sure, can someone clarify this


    atar goal:91 but will be happy with 85+

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    Re: HSC Biology Marathon 2015

    Never mind i got it now

  14. #39
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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by DepressedPenguino View Post
    Never mind i got it now
    What's the answer cos I'm not sure aswell lol


    atar goal:91 but will be happy with 85+

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by duhdevitt View Post
    Well from my notes:
    Lymph nodes store lymphocytes and macrophages. Macrophages are developed from monocytes which are a type of phagocytes. So I'm pretty sure phagocytosis occurs in lymph nodes as they store phagocytes. I'm not 100% sure, can someone clarify this


    atar goal:91 but will be happy with 85+
    Yeah i just found that macrophages do exist in the lymph nodes too !

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    Senior Member Fiction's Avatar
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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by BlueGas View Post
    The theory of evolution is supported by Paleontology, which is the study of fossils. A fossil record shows the sequence of the earliest of life to today's present organisms, this supports the theory of evolution and suggests that there is evidence of change in organisms. An example is horses:

    - Early horses were small animals, with four toes and a small check span.
    - Modern horses are large horses, with one toe and a large check span.

    The fossil record of horses shows that horses evolved from being small, having more than one toe and a small check span to horses that are large, have one toe and a large check span.


    I don't know the answer to why evolution is not supported by paleontological evidence, I haven't come across such a question before.
    Oh I made up that question haha
    I was thinking along the lines of the differences between gradualism and the punctuated equilibrium model.

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by Fiction View Post
    Oh I made up that question haha
    I was thinking along the lines of the differences between gradualism and the punctuated equilibrium model.
    Yeah maybe Gradualism may not support the theory of evolution. Darwin proposed that populations change slowly and gradually (gradualism) over time. However, this doesn't support the theory of evolution because the environment doesn't continually change, and this is proved by the fossil record of organisms such as the dinosaurs, they were present in large numbers, then as the environment changed, most dinosaurs became extinct.

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by astab View Post
    Why do freshwater fish actively absorb salts if they gain a lot of water by osmosis? Wouldn't salt absorption attract even more water, causing it to burst?
    Feshwater fish's gills are impermeable to water

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    Re: HSC Biology Marathon 2015

    Do T cells or T helper cells become memory T cells? I am not sure

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by DepressedPenguino View Post
    Do T cells or T helper cells become memory T cells? I am not sure
    T-cells - more specifically, cytotoxic (killer) T-cells become memory T-cells after they've triggered specific immune responses against an antigen. Helper T-cells act more efficiently in the event of subsequent exposures to the same antigen.

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by DepressedPenguino View Post
    Feshwater fish's gills are impermeable to water
    I thought that freshwater fish gain water by osmosis? Since their surrounding environments are highly diluted, water rushes into the fish to create an isotonic balance of solutes in and outside the fish. But why does it absorb salts if it wants to get rid of water?

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by astab View Post
    T-cells - more specifically, cytotoxic (killer) T-cells become memory T-cells after they've triggered specific immune responses against an antigen. Helper T-cells act more efficiently in the event of subsequent exposures to the same antigen.
    lol i didnt know cytotoxic T cells can become memory T cells. hmm pretty interesting

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    Re: HSC Biology Marathon 2015

    Question: In humans, brown eyes (B) are dominant over blue eyes (b). A man marries a blue eyed woman, they have two children, a brown eyed boy and a blue eyed girl. What are the genotypes of the parents and children?

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    Re: HSC Biology Marathon 2015

    Quote Originally Posted by BlueGas View Post
    Question: In humans, brown eyes (B) are dominant over blue eyes (b). A man marries a blue eyed woman, they have two children, a brown eyed boy and a blue eyed girl. What are the genotypes of the parents and children?
    Brown eyed boy: B b
    Blue eyed girl: b b
    Man: B b
    Woman: b b

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    Re: HSC Biology Marathon 2015

    Question: Is the trait in the following pedigree dominant or recessive? Explain why. (2 marks)


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