Figure 3(a) and Figure 3(b) illustrate the final stages of an experiment to demonstrate a physical process which occurs in living cells. Study the illustration carefully and answer the questions that follow.

a)
I. Retort stand (or clamp stand)
II. Thistle funnel
III. Beaker

b)

(i) The physical process being demonstrated is osmosis.

c)

(i)

• In Figure 3(a), the level of water in part labeled II will rise.
• In Figure 3(b), the level of water in part labeled II will remain the same.

(ii)

• Explanation for Figure 3(a): Water molecules move by osmosis from the region of higher water potential (the pure water in the beaker) to the region of lower water potential (the sugar solution inside the thistle funnel) across the partially permeable cellophane membrane. This net movement of water into the thistle funnel causes the volume of the solution to increase, leading to a rise in the level in the thistle funnel tube.
• Explanation for Figure 3(b): There is no net movement of water because the water potential inside the thistle funnel (pure water) is equal to the water potential outside the thistle funnel (pure water). Therefore, no net osmosis occurs, and the water level in the tube remains unchanged.