Monday 21 January 2013

2.12 understand definitions of diffusion, osmosis and active transport

Diffusion is when molecules move from a area of high concentration to a area of low concentration

Osmosis is the movement of water, it follows the rule that water will move from a dilute solution to a concentrated solution.

Active transport is molecules being moved from an area of low concentration to an area of high concentration  energy is needed to make this happen hence 'active'

17 comments:

  1. Through osmosis, you have to remember across a partially permeable membrane I think

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    1. yeah thats right, you need to have that to get marks

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    2. Osmosis: A special type of diffusion where only wáter moves acroos a partially permeable membrane from an área of high concentration of wáter to an área of lower concentration of wáter down the conentration gradient. An example of a partially permeable membrane is a cell membrane.

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    3. Osmosis: A special type of diffusion where only wáter moves acroos a partially permeable membrane from an área of high concentration of wáter to an área of lower concentration of wáter down the conentration gradient. An example of a partially permeable membrane is a cell membrane.

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  2. Y and S is right, osmosis is across a partially permeable membrane, but useful notes anyway ;)

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  3. Don't forget it is NET movement of molecules and water for Diffusion and Osmosis!

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  4. Full definitions
    Diffusion:
    The net movement of particles from an area of high concentration to an area of low concentration until equillibrium is reached.
    Osmosis:
    The net movement of water particles across a semi permeable membrane from an area of high water potential to an area of low water potential until equillibrium is reached.

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    1. Osmosis and diffusion is also the passive net movement

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  5. This comment has been removed by the author.

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  6. Suggestions for improvement:


    Diffusion: when molecules move from an area of high concentration to an area of low concentration

    Osmosis: the net movement of water, from a high concentration to a low concentration through a partially permeable membrane

    Active transport: molecules being moved from an area of low concentration to an area of high concentration with ENERGY across a concentration gradient

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  7. Energy is only needed in primary active transport

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

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

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  9. more at

    http://igcse-biology-notes.blogspot.hk/2017/06/212-understand-definitions-of-diffusion.html

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