Transport In And Out Of Cells

Question 1

Investigating cell membrane permeability – the effect of temperature on beetroot cell membranes:

Answer 1

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

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.
5. Carry out colorimetry (use the blue filter).

Question 2

Higher the permeability… (colorimeter)

Answer 2

The higher the permeability, the more pigment released, the higher the
absorbance reading.

Question 3

Investigating diffusion Concentration:

Answer 3

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.

Question 4

SA

Answer 4

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 5

Temp

Answer 5

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.

Question 6

To factors that affect permeability of cell membranes

Answer 6

Temp

Concentration of solvent

Question 7

Effect of temp

Answer 7

Increase temp - increase membrane permeability

Question 8

Concentration effect

Answer 8

Increase ethanol concentration = increases membrane permeability = more gaps form