(a) (i) What is osmosis? Osmosis is the movement or diffusion of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration - Leaving Cert Biology - Question 7 - 2005

A selectively permeable membrane is a type of barrier that allows certain molecules or ions to pass through while restricting others. This characteristic is crucial for maintaining homeostasis in biological cells, as it controls the movement of substances in and out of the cell.

[Diagram illustrating a setup, such as a visking tubing filled with a solution in one beaker and another solution in the surrounding beaker, but not shown here.]

To demonstrate osmosis, I began by filling a visking tubing with a sugar solution and sealing it at both ends. The tubing acts as a selectively permeable membrane. I then placed this tubing into a beaker containing pure water. Over a period of time, water from the beaker entered the tubing through osmosis, diluting the sugar solution inside. During the experiment, I monitored the setup and recorded observations on the concentration changes.

I was able to tell that osmosis had occurred by observing that the visking tubing became swollen. This swelling indicated that water had moved into the tubing, resulting in a higher volume of liquid inside as compared to the initial state. The increase in liquid volume in the tubing was evidence of water movement into the more concentrated solution.