Fill in the column headings in Table 1.1.
Fig. 1.2 gives the balance readings for the potato cylinders taken from the 0% and 8% salt solutions after 40 minutes. Enter these masses as ‘final mass’ in Table 1.1.
Use Table 1.1 to calculate the change in mass for each of these potato cylinders.
Water can move into and out of potato cells by osmosis. Salt cannot move into and out of potato cells. Use this information to explain the results in the test-tube containing 6% salt solution.
Explain why it is important that all the potato cylinders have the same mass at the start of the investigation.
The salt solutions were prepared by combining different volumes of a 10% salt solution and distilled water. Calculate the volumes of 10% salt solution and distilled water needed to make $10\,\text{cm}^3$ of a 4% salt solution.
Explain why using a $10\,\text{cm}^3$ measuring cylinder is better than using a $50\,\text{cm}^3$ beaker for measuring the volumes of distilled water and salt solution.
Explain why it is important that the students dried the potato cylinders before obtaining their final mass.
Construct a graph of percentage concentration of salt solution against change in mass. Join your points with ruled lines.
Each potato cylinder had a starting mass of $3.0\,\text{g}$. Use your graph to determine the final mass of a potato cylinder placed in a 3% salt solution. Show your working on your graph.
Design an investigation to determine the concentration of salt solution in which movement into and out of potato tissue is equal. Your investigation should be based on the method described on page 3 but using changes in length of the potato tissue and not changes in mass. Give full experimental details.
Identify the dependent variable in the investigation you have designed.
Potatoes contain starch. Describe a test to confirm the presence of starch. Include the observation for a positive result.
The starch can be broken down into glucose for the plant to use in respiration. Name the reagent used to test for the presence of glucose.