Tuesday 12 February 2013

2.20 describe the structure of the leaf and explain how it is adapted for photosynthesis

In terms of the basic features leaves have a large surface area; this allows them to absorb more sunlight. They are also thin, meaning that carbon dioxide has a shorter way to travel. In addition the stomata allow the entrance of carbon dioxide.

The more complex adaptations are of the internal leaf structure. The epidermis is thin and its transparent this means that more light can reach the palisade cells underneath the upper epidermis. The palisade cells themselves are er to the top of the leaf so they can absorb more if the light; they contain chloroplasts so that they can absorb the light. The spongy layer has air spaces in: these allow for carbon dioxide to diffuse through the leaf, and they increase the surface area. The wax cuticle is thin and made out of wax so it doesn't stop the sunlight from getting through.
Shows the waxy cuticle on top of the upper epidermis.Under this is the palisade mesophyll layer and spongy mesophyll layer, which has air spaces in it. At the bottom, is the lower epidermis and wax cuticle. Gases are exchanged through the stoma. On each side of the stoma there is a guard cell with chloroplasts.

15 comments:

  1. do you need to know the complex adaptations for IGCSE?

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  2. what did you get in your gcses hannah? also when did you start revising?

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    1. If your GCSEs are this summer (like me) then revise now!

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    2. This comment has been removed by a blog administrator.

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  3. how many marks u got in bio

    Hannah

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    1. This comment has been removed by the author.

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  4. This comment has been removed by the author.

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  5. people like u r life savers

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

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

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  7. look at for more

    http://igcse-biology-notes.blogspot.hk/2017/06/220-describe-structure-of-leaf-and.html

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    Replies
    1. That spec is for a different exam board.

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    2. it's for the same exam board, they are both edexcel, but just different specification because of adaptations.

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  8. do we need to know the complex adaptations for GCSE (2019)?

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