Integrate a planning and analysis response
Practise a complete unfamiliar investigation: prediction, variables, method, safety, data processing, conclusion and evaluation.
Cambridge International Biology 9700, 2028–2030. Paper 5 assesses planning, analysis and evaluation. These original practice tasks are not Cambridge exam questions or mark schemes.
Before you begin
- Use biological vocabulary and basic calculations from the AS Biology course. Follow your school laboratory rules and teacher instructions for all practical work.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What holds a complete practical response together?
What you will learn
- Build a coherent method for an unfamiliar context.
- Connect data processing and statistical choice to the question.
- Present a balanced conclusion and targeted evaluation.
Use a response structure
Start by defining the tested relationship and prediction. Identify variables and standardised conditions. Then specify a range, intervals, repeats, a measurement method, a control and a safe sequence.
Plan the analysis before collecting data: tables, graph axes, units, summary calculations and a suitable test if required. State what evidence would support or challenge the prediction.
Check the whole chain
A strong evaluation connects an observed weakness to the confidence of a conclusion and a practical improvement. Check that your method measures the stated dependent variable and that each planned control supports validity.
When a prompt gives unfamiliar context or equipment, use information provided rather than inventing unavailable specifications. State assumptions where they matter.
Pause and explain
Which response best evaluates a method?
Worked example
Design a test of how sodium chloride concentration affects water uptake by potato cylinders.
Show the worked solution
- Predict that higher external solute concentration reduces mass gain or increases mass loss.
- Use at least five concentrations, equal cylinders, a fixed time and repeated samples.
- Blot and weigh consistently; calculate percentage mass change.
- Use a graph, identify pattern and evaluate variation.
Answer Prepare at least five labelled sodium chloride concentrations. Place equal-sized potato cylinders in equal volumes for the same time and temperature, repeat each concentration, blot with a consistent method and measure mass before and after. Calculate percentage mass change, graph it against concentration and assess spread, anomalies and control quality.
From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Plan a test of how light intensity affects leaf-disk flotation time. Include variables, range, repeats and one control.
Give me a hint
Make the measured response and timing rule explicit.
Compare my reasoning
- Use at least five measured light intensities.
- Place equal numbers and size of disks in the same solution volume.
- Repeat each level and record time until a defined flotation threshold.
- Keep temperature and solution concentration constant.
Vary measured light intensity across at least five values. Use equal leaf-disk sizes and counts in the same solution volume, define the flotation endpoint, repeat each condition, record time and standardise temperature and solution concentration.
Look for these in your work
- Variable and response defined
- Range and repeats included
- Controls named
A results table has a concentration series and percentage mass change. What graph axes and one analysis should be used?
Give me a hint
Put the changed variable on x and measured response on y.
Compare my reasoning
- Plot concentration / mol dm⁻³ on x.
- Plot percentage mass change / % on y.
- Summarise replicates and inspect spread and trend.
Use concentration / mol dm⁻³ on the x-axis and mean percentage mass change / % on the y-axis, with a graph suitable for continuous variables; show or discuss variation across repeats.
Look for these in your work
- Axes correct
- Units included
- Variation considered
The final conclusion supports the prediction but only one cylinder was tested at each concentration. What qualification and improvement are needed?
Give me a hint
Distinguish observed pattern from confidence in it.
Compare my reasoning
- State that the pattern is consistent with the prediction.
- Explain that one result per concentration cannot estimate spread.
- Collect repeated cylinders at every concentration.
The measured pattern is consistent with the prediction, but confidence is limited because there are no replicates to estimate variation. Repeat each concentration with multiple cylinders and compare the spread and means.
Look for these in your work
- Support qualified
- Evidence limit identified
- Improvement targeted
Common mistakes
- Changing cylinder dimensions, time and concentration together.
- Reporting mass change without normalising for starting mass when groups differ.
- Choosing a statistical test without considering data type and sample structure.
What can you explain now?
What holds a complete practical response together?
Compare with the explanation
The method, measurement and analysis all answer the same question
Alignment makes the evidence useful for the stated prediction.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Before writing a Paper 5 response, how will you make sure the prediction, method and analysis answer one question?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.