Diffusion, Osmosis & Active Transport

What is diffusion?

Diffusion is the movement of particles from a high concentration to a low concentration

What is osmosis?

The movement of water molecules from a high to a low concentration through a partially permeable membrane

What are the steps for the osmosis practical?

1- Cut up a potato into identical cylinders and get beaks with different sugar solutions in them. One of them should be pure water.

2- Measure the mass of the potato cylinders, then leave one cylinder in each beaker for twenty-four hours.

3- After that time take them out, dry them with a paper towel and measure their masses again.

4- If the cylinders have drawn in water by osmosis they’ll have increased in mass but if water was drawn out they’ll have decreased in mass.

5- Calculate percentage change in mass and then plot the graph.

What is the dependent variable for the osmosis practical?

The mass of the potato cylinders

What is the independent variable in the osmosis practical?

The concentration of the sugar solution

What are the control variables in the osmosis practical?

Volume of the solution, temperature and the time

How can you prevent errors in the investigation?

Repeat the experiment and calculate a mean percentage change in each concentration

What is active transport?

Active transport is the movement of particles from a low concentration to a high concentration