A researcher investigates the effect of different water potentials of mannitol solution on cubes of sweet potato tissue.
This is the method that they use:
Step 1 Cut five cubes of sweet potato tissue using a knife and cutting tile.
Step 2 Place each sweet potato cube in a beaker containing a different concentration of mannitol solution.
Step 3 Leave the sweet potato cubes in the mannitol solutions for 3 hours.
Step 4 Remove the sweet potato cubes from the mannitol solutions.
The researcher wants to calculate the percentage change in mass for each sweet potato cube. They want to use the method above to collect the data they need, but have missed some steps from the method. Describe the additional steps needed in the method to find the data.
State two variables that the researcher should control in this investigation.
Describe how the researcher could find out if their data is both repeatable and reproducible.
Some of the sweet potato cubes decreased in mass. Explain why some of the sweet potato cubes will decrease in mass.
82 exam-style questions on OCR GCSE Biology 2.1 Supplying the cell, covering 2.1.1 Transport across cell membranes, 2.1.2 Mitosis and the cell cycle, 2.1.3 Importance of cell differentiation, and 2.1.4 Stem cells. Each one has a worked solution and a mark scheme showing where the marks go.