Answer:
See the answer below
Explanation:
There was an increase in the mass of the courgette in the sugar solution of 0.2 moles per dm3 because the solution is hypotonic to the cells of the courgette.
A hypotonic solution is one whose concentration is less than that of the cell sap of cells placed in it. Consequently, water molecules will move from the solution into the cells by osmosis, causing a gain in weight for the cell.
<u>Hence, the gain in the weight of the courgettes is as a result of movement of water from the sugar solution into the cells of the courgettes.</u>
At a sugar concentration of 0.4 moles per dm3, the solution is isotonic to the cells of the courgettes. It means the cells have the same concentration as the surrounding sugar solution and hence, their is no net movement of water in and out of the courgettes. This is the reason there was no change in the weight of the courgettes at the concentration.
Above sugar concentration of 0.4, the solution will become hypertonic to the courgettes and water will move out of the courgettes into the surrounding solution which will lead to a loss in weight for the courgettes.
