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From CrookED 132 page PPT
BUBBLE MEMBRANE
One tray for mix
Four drinking straws
One stretch of thick string
BUBBLE MIX - (best made night before) – 900ml of water, 100ml of dishwashing detergent (the yellow one from canteen works best) and 25ml of glucose syrup (woollies).
Watch https://vimeo.com/52263821 for ideas how this exhibit might work – will also give you bio concepts that the membrane model is linked to eg.. cell is born (blowing a bubble), cell membranes are fluid and flexible (put hand through), membranes can reform when broken, channel proteins float within the cell membrane (use string circle), channel proteins provide passageway through a membrane, membrane bound organelle, binary fission – if they apply to Junior Science.
Exchange of materials across membranes (sees CrookEd Science ppt)
Key Points
Substances diffuse according to their concentration gradient; within a system, different substances in the medium will each diffuse at different rates according to their individual gradients.
After a substance has diffused completely through a space, removing its concentration gradient, molecules will still move around in the space, but there will be no net movement of the number of molecules from one area to another, a state known as dynamic equilibrium.
Several factors affect the rate of diffusion of a solute including the mass of the solute, the temperature of the environment, the solvent density, and the distance traveled.
For SA: V - look up DET guide to Module 1. Good activity in re SA:V - use rubix cube - how many little squares in one rubix cube (9x6 = 54) then if you pull them all apart it is 54x6 for total surfaces (SA)
Or wrap a box set as a box set in wrapping paper. Wrap individual cds now - which has more wrapping paper
THE CELL MEMBRANE AND SURFACE AREA DEMOS.docYear 11 - build-a-membrane (1).pdf
exam choice 2020
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