PAG08 = Transport In and Out of Cells

Question 1

How do we prepare beetroot when investigating effect of temp on membranes?

Answer 1

Use a scalpel to cut five equal sizes of beetroot. Rinse the pieces to remove any
pigment released during cutting.

Question 2

How do we investigate the effect of temp on membranes?

Answer 2

Add the 5 pieces to 5 different test tubes, each containing 5 cm3
of water.
3. Place each test tube of in a water bath at different temperatures for the same length of
time using a stopwatch.
4. Remove the pieces of beetroot, leaving just the liquid

Question 3

How do we show absorbance to show effect on membranes?

Answer 3

Carry out colorimetry (use the blue filter).
6. The higher the permeability, the more pigment released, the higher the
absorbance reading.

Question 4

What are factors to investigate when looking at diffusion?

Answer 4

Concentration; surface area; temp

Question 5

How do we investigate how concentration effects diffusion?

Answer 5

1. Make some agar jelly with phenolphthalein and dilute sodium hydroxide. This will
   make the jelly pink.
2. Prepare 5 test tubes containing HCl in increasing concentrations e.g. 0.2M, 0.4M,
   0.6M, 0.8M and 1.0M (synoptic link – serial dilutions).
3. Using a scalpel, cut out 5 equal size cubes from the agar jelly.
4. Put one of the cubes into the first test tube and use a stopwatch to time how long it
   takes for the cube to turn colourless.
5. Then repeat for the other concentrations, using a new cube each time.
6. The highest concentration of HCl will have the fastest colour change as it has the
   steepest concentration gradient.

Question 6

How do we investigate how surface area effects diffusion?

Answer 6

1. Use a similar method to the concentration method but cut the cubes in different sizes
   and work out the surface area to volume ratio.
2. The smallest cube with the greatest surface area to volume ratio would go
   colourless fastest.

Question 7

How do we investigate how temp effects diffusion?

Answer 7

1. Use a similar method to the surface area method but cut into equal sized cubes.
2. Prepare several boiling tubes with the same concentration of HCl.
3. Put the boiling tubes in water baths with different temperatures.
4. The higher temperatures will make the cubes go colourless faster.