Osmosis & Diffusion

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Isotonic Solution - both solutions have same concentrations of solute.

Slide 13

Plant and Animal Cells put into

various solutions

Slide 14

Types of Transport

Slide 15

Today’s Lab

We are using dialysis tubing as the cell membrane - It is selectively permeable

The solute is either the eosin starch solution or the sugar solution

What is the solvent?

Slide 16

Membrane Permeability

Solute is eosin-starch-chloride solution

Solvent is Water

Indicator for presence of starch is IKI

Starch is made of amylose and amylopectin – amylopectin is insoluble

Iodine is not very soluble in water, but with KI it forms a I3- (triiodine ion) which is soluble.

I3- combines with the amylose and the starch molecule turns blue-black.

Slide 17

Test for Starch

Elmhurst College Website

Slide 18

Test for Chloride ions

Indicator for presence of chloride ions is silver nitrate, AgNO3

A white precipitate, AgCl, forms if chloride is present.

Slide 19

Test for Sulfate ions

Indicator for the presence of sulfate ions is Barium chloride, BaCl

Barium sulfate, BaSO4 - forms a white precipitate

BaCl + NaSO4 ----> BaSO4 + NaCl

Slide 20

Living Cells

Beet cubes will be used to see the result of boiling and adding alcohol to a live membrane.

Yeast cells are used to see effects of heat

Fern gametophytes are used to see result of putting live cells in solutions of varying tonicity

Slide 21

Osmosis

We will make an osmometer to see osmosis

Sugar solution in a dialysis tube is used to simulate a cell membrane.

Various concentrations of solute may be used around the room.