CM-UY 1004 Lecture Notes - Lecture 5: Red Onion, Distilled Water, Dialysis Tubing
14 Oct 2016
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Beaks of finches: what you did: played finches with different beak characteristics competing for food. Different environmental conditions (food) favored different species of finch (beaks), allowing some to survive and reproduce, but not others. (survival of the fittest) Natural selection, competition and variation drive evolution. (species change over time) Diffusion through a membrane a) part a: what you did: made a model cell using dialysis tubing. Put starch indicator (iodine) outside cell: what you saw: inside of cell turned black because iodine diffused into the cell because outside of the cell was not black, you know the starch did not diffuse through the membrane. Used blue glucose indicator (benedict"s solution) to see that glucose did diffuse through the membrane: what you learned small molecules (glucose, iodine) can diffuse through a membrane on their own. Large molecule (starch) cannot diffuse through a membrane on their own.
