Required Practical 4

Question 1

Permeability can be changed, what two variables can be changed?

Answer 1

Permeability can be changed by temperature and/or the concentration of solvents (ethanol)

Question 2

What happens to the cell surface membrane’s permeability as the temperature increases?

Answer 2

As the temperature increases, the cell surface membrane also increases

Question 3

Why does the cell surface membrane’s permeability increase as the temperature increases?

Answer 3

The cell surface membrane increases because the proteins in the membrane denatures as the heat damages the bonds in their tertiary structure. This creates gaps in the membrane, so it is easier for molecules to pass through it

Question 4

What happens to the cell surface membrane’s permeability at lower temperatures?

Answer 4

At lower temperatures, phospholipids have little energy and are packed closely together to the membrane rigid. This causes a decrease in permeability and restricts molecules from crossing the membrane