Friday, 22 February 2013

2.43 describe experiments to investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator

hydrogen-carbonate indicator is an indicator for carbon dioxide: under normal levels (atmospheric) of carbon it is orange; an increase turns it yellow; a decrease turns it purple.
Fill a test tube quarter full with HCIS, attach a leaf to a bung and put in the test tube; observe the indicator colour in different light intensities.
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18 comments:

  1. Anonymous3 December 2015 at 07:50

    can you explain why these changes are occuring?

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    1. HannahHelp3 December 2015 at 08:11

      As light increases, so does photosynthesis (because the reaction requires sunlight to work). Photosynthesis uses up carbon, so the more light, the lower the amount of carbon in the tube.

      Delete
    2. Anonymous21 April 2016 at 14:04

      does respiration not factor in

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    3. pmk01010 May 2016 at 16:51

      The rate of respiration of a plant is generally constant, therefore does not factor in.

      Delete
  2. Unknown23 March 2016 at 09:24

    This comment has been removed by the author.

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  3. Unknown23 March 2016 at 09:24

    This comment has been removed by the author.

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  4. Anonymous27 November 2016 at 04:00

    what does the HCIS in this entry mean?

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  5. Unknown27 December 2016 at 13:59

    what color changes do you observe with the hydrogen carbonate indicator? might be useful to add maybe?

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  6. Unknown31 May 2017 at 13:48

    maybe change the 'under normal levels of carbon' to 'carbon dioxide', seeing as that's what the bitsize page says (and we all know that bitesize is de best)

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  7. Mike Tsang26 June 2017 at 02:49

    The Biology Syllabus has changed.... New Syllabus Blog:

    http://igcse-biology-2017.blogspot.hk

    ReplyDelete
  8. SophieRice26 June 2017 at 18:00

    more at

    http://igcse-biology-notes.blogspot.hk/2017/06/243-describe-experiments-to-investigate.html

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  9. Unknown31 May 2018 at 00:37

    what is HCIS?

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    Replies
    1. Anonymous4 June 2018 at 02:19

      hydrogen carbonate indicator solution

      Delete
  10. ieatshoesforbreakfast6910 June 2018 at 04:30

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    ReplyDelete
  11. Unknown16 October 2019 at 03:41

    Why there is a high amount of carbon dioxide in the leaf in dark

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  12. William3 April 2020 at 13:44

    Hi I am taking my GCSE next year and I am very thankful for this recourse. But just making sure would you know if this is still valid for my GCSE? or should I look elsewhere

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