To Demonstrate Osmosis

Question 1

Name the material you used to act as a selectively permeable membrane.

Answer 1

Visking tubing

Question 2

Under what conditions does osmosis occur?

3

Answer 2

There must be different concentrations on either side of the membrane for osmosis to occur

I.e. there must be a high water concentration on one side and a low water concentration on the other side

The presence of a concentration gradient is necessary

Question 3

Why did you use Visking tubing?

Answer 3

Visking tubing acts as a selectively permeable membrane

Question 4

How did you know osmosis had taken place?

2

Answer 4

The mass of the tubing containing the sucrose solution increased

The tubing containing the sucrose solution got fuller and its turgidity increased

Question 5

What characteristics of membranes were you demonstrating the effect of osmosis?

Answer 5

That they are selectively permeable

Question 6

Name the control you used during this experiment?

Answer 6

I used distilled water in the Visking tubing as the control

Question 7

Diffusion is a passive process. Explain the underlined term

Answer 7

No energy is required

Question 8

Explain the term selective permeability.

Answer 8

A selectively permeable membrane allows some but not all molecules to pass through

Question 9

Suggest an advantage of the cell of having a selectively permeable membrane
(2)

Answer 9

Substances can be kept in or kept out

Substances can be let in or let out

Question 10

Name two substances that enter a human muscle cell by diffusion
(2/4)

Answer 10

Oxygen

Glucose

Water

Amino acids

Question 11

For what purpose did you use Visking tubing?

Answer 11

As a selectively permeable membrane

Question 12

Define osmosis

Answer 12

The movement of water molecules across a semi-permeable membrane from a region of high water concentration to a region of low water concentration

Question 13

Describe how you carried out the investigation

6

Answer 13

Made up a concentrated sucrose solution by dissolving a large amount of sucrose in warm water

Filled one tube of Visking tubing with the sucrose solution and tied a knot at the top

Filled one tube of Visking tubing with distilled water and tied a knot at the top

Dry each tube and note the mass of each sealed tube

Place each tube in a container of distilled water and leave for 30 mins

Remove tubes, dry them and note the mass of them

Question 14

Describe the control that you used

Answer 14

Visking tubing filled with distilled water

Question 15

What is the purpose of the control you used.

Answer 15

Used to compare the results from the tubing containing the sucrose solution

Question 16

Compare the results that you obtained in the experiment and in the control.
(2)

Answer 16

Mass of tubing containing the sucrose solution increased

Mass of tubing containing the distilled water remained the same

Question 17

Give one example of food preservation based on osmosis

Answer 17

Adding sugar to jam to create a concentrated sucrose solution

Question 18

Explain the term diffusion.

Answer 18

The spreading out of molecules from a region of high concentration to a region of low concentration

Question 19

Osmosis is a special case of diffusion. Explain.

Answer 19

Osmosis is the diffusion of water across a concentration gradient

Question 20

Give one example of food preservation based on osmosis. Explain why this process works.
(2)

Answer 20

Adding sugar to jam to create a concentrated sucrose solution

Kills microorganisms that would cause the spoilage of food by dehydrating them by osmosis - causes their cells to lose water