This apparatus can be used to show osmosis. (a) Explain what happens to the level of sucrose solution in the glass tube. [3]

(b) Describe how this apparatus could be modified to measure the rate of osmosis at different temperatures. [3]

A. The level of sucrose solution will rise in the glass tube because water molecules will pass through the semipermeable membrane into the tube as water potential is higher outside than inside the tube.

B. The apparatus can be modified to measure the rate of osmosis at different temperatures by doing the following :

1. Using a waterbath in order to heat the water and a thermometer to measure different temperatures.

2. Using a scale such as a ruler attached to the glass tube to measure the increase in height at different temperatures.

3. Using a stopwatch to record time taken for unit increase in the height of waterat different temperatures.

Explanation:

A. Osmosis is the movement of water molecules from a region of low solute concentration or high water potential to a region of high solute concentration or low water potential through a semipermeable membrane until equilibrium concentration is attained.

The movement of water molecules is based on a concentration gradient, from a region where there are more water molecules to a region where there are fewer water molecules.

The sucrose solution has a higher solute concentation but lower water potential due to fewer water molecules compared to water in the beaker, therefore, water molecules will pass through the semipermeable membrane into the glass tube resulting in an increase in the level of sucrose solution in the glass tube.

B. The apparatus can be modified to measure the rate of osmosis at different temperatures by doing the following :

1. Using a waterbath in order to heat the water and a thermometer to measure different temperatures.

2. Using a scale such as a ruler attached to the glass tube to measure the increase in height at different temperatures.

3. Using a stopwatch to record time taken for unit increase in the height of waterat different temperatures.

a. by using fur or clothes to trap heat energy near the body