d) movement of substances into and out of cells

Define diffusion?

The movement of particles from an area of high concentration to an area of lower concentration.

Define osmosis?

The movement of water molecule across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.

Define active transport?

The movement of particles against a concentration gradient from an area of lower concentration to ad area of higher concentration using energy.

4 factors that increase movement of substances?

1. Larger surface area to volume ratio

2. Smaller distance

3. Higher temperature

4. Bigger difference in concentration

How to investigate diffusion in a non-living system?

1. Make agar jelly with phenolphthalein and dilute sodium hydroxide.

2. This will make jelly pink.

3. Put dilute sodium hydrochloric acid in a beaker.

4. Cut out few cubes of jelly and put them in beaker of acid.

5. Leave cubes for a while then they turn colourless since acid diffuses into jelly and neutralises sodium hydroxide.

How to investigate osmosis in living systems?

Living system - potato cylinders

1. Cut up potato into identical cylinders.

2. Get beaker with different sugar solutions in them.

3. One beaker should be pure water another should be a very concentrated sugar solutions and others concentrations in between.

4. Measure length of cylinders.

5. Leave few cylinders in each beaker for 30 min or so.

6. Take them out and measure again.

How to investigate osmosis in non-living systems.

Non-living systems - visiting tubing

1. Fix some visiting tube over end of thistle funnel.

2. Pour sugar solutions down glass tube into thistle funnel.

3. Put thistle funnel into beaker of pure water.

4. Measure where sugar solutions comes up to on glass tube.

5. Leave apparatus overnight.

6. Measure where solution is in glass tube.