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Thread: General Exam Thoughts

  1. #26
    Don't shoot the messenger bheck7's Avatar
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    Re: General Exam Thoughts

    Quote Originally Posted by neeksy45
    i thought that at first, but banded iron formations are made in the water, therefore the oxygen in the oceans would be used up in that, so oxygen would accumulate in the atmosphere first?
    that was my reasoning in my head anyway,not sure how right it is.haha.
    nup. the end of formation of BIFS=the introduction of oxygen into the atmosphere. not the other way round.

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  2. #27
    Don't shoot the messenger bheck7's Avatar
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    Re: Did we just get slipped a...

    Quote Originally Posted by devilru
    You do realise you're only meant to attempt ONE question from section II.
    hahahahaaha! there's always one.

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    Re: Did we just get slipped a...

    what did you say for the oldest life on earth or whatever it was?

  4. #29
    jay son em el
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    Re: Did we just get slipped a...

    3.6Ba, and can be proved with carbon 12/13 ratios
    :/

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    Re: Did we just get slipped a...

    oh ok i said 3.8 but i think a range would be accepted because diffrent sources say diffrent things. like i have a book that says 4 billion

  6. #31
    jay son em el
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    Re: Did we just get slipped a...

    yeah, i'll bet 3.8 would still get full marks.
    :/

  7. #32
    Don't shoot the messenger bheck7's Avatar
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    Re: Did we just get slipped a...

    Quote Originally Posted by jasonml
    yeah, i'll bet 3.8 would still get full marks.
    yeah it would, because it IS 3.8 GA

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  8. #33
    Member ConquerDiscover's Avatar
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    Re: Did we just get slipped a...

    Quote Originally Posted by jasonml
    3.6Ba, and can be proved with carbon 12/13 ratios
    Yeah same i wrote about the carbon 12/13 ratio! Although, i said 3.8 Billion years ago.

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    Re: Did we just get slipped a...

    I guessed 3.8 bill as well, wrote down 4.2 at the start then changed it. I knew it was carbon 12/13 ratios though.

  10. #35
    Member Aaron.Judd's Avatar
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    Re: Did we just get slipped a...

    I tossed up between writing 3.8 and 3.5 billion years. 3.8 billion years is the age of the Australian contientn hence I reasoned it was 3.5 billion years (somewhere like Greenland life was discored of this age). So I went with 3.5 billion. They might be pretty specific though, i.e. if I was markign it I woudl allo 100 million years either side. I.e. if it is 3.6, I'd accept 3.5 - 3.7 and not 3.8 (especailly as that is the age of the Australian continent).

    I too wrote about carbon 12:carbon 13 isotopic evidence.
    Aaron Judd, 2008 HSC

  11. #36
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    Re: Did we just get slipped a...

    But, it didn't specify that they were referring solely to the Australian stromatolite fossils. Plus, one of the syllabus points is; outline stable isotope evidence for the first presence of life in 3.8 x 109 year-old rocks and on Hsc Online, it states that using stable isotopes, evidence for life dating to 3800 million years has been found in rocks from Greenland, Australia and South Africa. So... I still think they would give marks for both 3.5 ba and 3.8 ba

  12. #37
    Junior Member stolenhotelpen's Avatar
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    Re: Did we just get slipped a...

    Quote Originally Posted by jasonml
    3.6Ba, and can be proved with carbon 12/13 ratios
    yeah same, i think a range is acceptable. i said 3.5bya
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  13. #38
    Junior Member stolenhotelpen's Avatar
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    Re: Did we just get slipped a...

    i totally forgot if it was carbon12/13..because i thought that can be only used for the past 50-60000years...??

    but at least i only answered ONE of the options bahahaha
    Class of 2009

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    Executive Member henry08's Avatar
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    Re: Did we just get slipped a...

    Quote Originally Posted by stolenhotelpen
    i totally forgot if it was carbon12/13..because i thought that can be only used for the past 50-60000years...??

    but at least i only answered ONE of the options bahahaha
    That is radioactive dating (absolute dating) using carbon, and carbon dating is only accurate to about 60,000 years.

  15. #40
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    Re: General Exam Thoughts

    I accidently wrote 1.8 instead of 3.8 and I realised it on my way home from the exam.

    I talked about c 12 and c 13 in the second part, but I said that it shows that life was around 1.8 billion years ago, so I'm assuming that it's possible that I wont get any marks for the second part either?

  16. #41
    Executive Member henry08's Avatar
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    Re: General Exam Thoughts

    If you wrote about carbon 12:carbon 13 isotopes, and got the date wrong you will defiantly get marks for part b and only los 1 mark for part a.

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