A student investigates the effect of different concentrations of salt solution on cylinders of potato tissue.
This is the method that they use:
Step 1 Cut five cylinders of potato tissue using a cork borer.
Step 2 Place each potato cylinder in a test tube containing a different concentration of salt solution.
Step 3 Leave the potato cylinders in the salt solutions for 4 hours.
Step 4 Remove the potato cylinders from the salt solutions.
The student wants to calculate the percentage change in mass for each potato cylinder. 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 student should control in this investigation.
Describe how the student could find out if their data is both repeatable and reproducible.
Some of the potato cylinders decreased in mass. Explain why some of the potato cylinders will decrease in mass.
194 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.