A screenshot of the simulation window is shown in Fig. 4. In the simulation, the top half of the blue space is considered the inside of the cell. The bottom half of the blue screen is considered the outside of the cell. The ‘Membrane’ separates the inside of the cell from the outside. The blue diamonds are water molecules and the green circles are solute molecules (sugar, salt, proteins etc.). You can add these to the cell environment by pressing the red buttons on the left. The slider at the bottom of the screen controls the speed of the simulation. ‘Check’ the 'Show Concentration' box to see the concentration of solute and water on either side of the membrane. The concentration of each substance is represented by a color-coded bar. The bar will increase or decrease in length as the simulation progresses, indicating the corresponding change in concentration. This visual representation is also known as a bar graph.

1. Add approximately 20 green circles, which represent molecules, to the inside of the cell. Observe the behavior of the molecules.

2. Pause the simulation.

3. Drag and drop 1-2 “leakage” green channels onto the membrane. Press the start button. Observe.

4. Answer question 1

5. Drag and drop 1-2 “leakage” blue channels onto the membrane.

6. Add 20 blue diamonds to outside of cell membrane.

7. Click on the box next to 'Show Concentration' tab to observe concentration of molecules on each side with help of the bar graph.

8. Let the simulation continue for 2 minutes.

9. Answer question 2