How to Approach Planning Questions in Cambridge A Level Biology (9700) Paper 5

Paper 5 is not a test of whether you can memorise one perfect experiment. It tests whether you can design a defensible investigation from the biological problem in front of you. The context may even be unfamiliar. What matters is whether you can identify the variables, build a workable method, measure the right thing precisely and explain how the quality and safety of the investigation will be controlled. Under the current 2025–2027 Cambridge International A Level Biology (9700) syllabus, Paper 5 is a 1 hour 15 minute written paper worth 30 marks. Around half of the paper, 14–16 marks, is allocated to planning, with the remainder testing analysis, conclusions and evaluation. That makes planning a major skill in its own right rather than a short practical-method add-on.

Know what Paper 5 planning is actually testing

Paper 5 divides its 30 marks roughly equally between planning and the later analysis, conclusion and evaluation skills.

Cambridge describes planning as developing a procedure to test a hypothesis or prediction from the context provided. Candidates may be asked to use particular information or apparatus, and the question may involve biology outside the taught syllabus. This is why trying to memorise a single enzyme, osmosis or photosynthesis template is unreliable: the method has to fit the actual problem.

Start with the independent and dependent variables

Before writing practical steps, identify what is being changed and what is being measured. The independent variable is the factor you deliberately vary. The dependent variable is the response you measure to see what effect that change has. A weak plan often names the variables too vaguely. "Change the concentration and measure the reaction" is not enough to guide an investigation. A stronger plan specifies how the independent variable will be varied and exactly what measurement will represent the dependent variable. For example, if concentration is changed, state how the different concentrations will be prepared. If enzyme activity is the response, state whether you will measure a volume of gas, a colour change, a mass change, or the time taken for a defined endpoint.

A useful planning check: can another student tell exactly what I will change, what I will measure, and what numerical or observable result I will record? If not, the variables are probably still too vague.

Control the variables that could actually change the result

Cambridge expects candidates to identify the key variables that must be standardised so that the hypothesis can be tested fairly. That does not mean writing a huge list of everything in the laboratory. The syllabus explicitly notes that variables expected to have only a minimal effect do not need to be standardised. Choose controls because they could influence the dependent variable. If temperature would alter an enzyme-controlled reaction, say how temperature will be maintained, such as with a thermostatically controlled water bath. If pH matters, describe the use of an appropriate buffer. If the amount of biological material matters, specify how equivalent samples will be selected or measured. The stronger answer does not just name the controlled variable; it states how it will be kept constant.

Write a prediction or hypothesis only as far as the question requires

Paper 5 can require a prediction linking the independent and dependent variables, either in words or as a sketch graph. The prediction should be testable and connected to an underlying biological hypothesis. If the expected relationship is increasing, decreasing, optimum-shaped or otherwise non-linear, make that relationship clear. Do not force a long theoretical explanation into the prediction unless the question requires it. The point is to establish what result you expect and why that expectation is biologically reasonable. If a sketch graph is requested, label the axes with the variables and units where appropriate and show the expected trend clearly.

Design a method that somebody could actually follow

The method should read as a logical sequence rather than a collection of practical buzzwords. Explain how the independent variable is changed, how the dependent variable is measured, how the important controls are maintained and how the apparatus is used to collect results. Precision matters. "Measure the gas produced" leaves several questions unanswered. A stronger version might specify using a gas syringe, recording the volume in cm³ over a defined time interval. "Use different concentrations" should become a realistic set of concentrations prepared by proportional or serial dilution where appropriate. Cambridge does not prescribe one universal number of concentrations or repeats; the range and intervals should be suitable for the biological question and capable of revealing the pattern being tested.

Measure with appropriate apparatus and precision

A planning answer should state what is measured, with what apparatus and to what useful precision. Choosing the apparatus is part of the design. A balance may be suitable for mass change, a colorimeter for absorbance, a gas syringe for gas volume, or a timer for a defined endpoint. The best choice depends on the dependent variable in the question. The same principle applies to time and sampling. If measurements are taken over time, state when they are recorded. If the investigation needs a range of temperatures or concentrations, choose values that are biologically realistic and spread widely enough to test the relationship. Avoid giving impressive-looking numbers that have no connection to the problem.

Use repeats to judge repeatability, not as a magic phrase

"Repeat the experiment to make it accurate" is one of the weakest stock phrases in practical Biology. Repeats mainly give information about repeatability and the spread of results. They can help reveal anomalous results and allow a mean or other summary to be calculated where appropriate. The number of repeats should not be memorised as a universal Cambridge rule. Instead, explain how replication helps you judge the quality of the data. Paper 5 can also ask students to consider standard deviation, standard error or 95% confidence intervals, so the broader idea is to assess how consistent and convincing the results are rather than simply writing "repeat three times".

Use control experiments only when they answer a real question

A control experiment can help show that the observed change is caused by the factor being investigated rather than another part of the setup. Cambridge includes appropriate control experiments within the planning expectations, but not every investigation needs the same type of control. For an enzyme investigation, a control might replace active enzyme with denatured enzyme or omit the substrate, depending on what needs to be demonstrated. In another context, the relevant control could be a zero concentration, an untreated sample or a baseline condition. The control should have a clear purpose in the logic of the investigation.

Make safety specific to the hazard in front of you

Paper 5 planning can require a simple risk assessment. Cambridge expects students to consider both the severity of a hazard and the probability of a problem occurring, then state precautions that reduce the risk where possible. Generic statements such as "wear a lab coat" or "be careful" are weak because they do not identify the actual risk. Match the precaution to the hazard: eye protection for a corrosive reagent, protection from burns around hot equipment, or appropriate containment and ethical treatment for living organisms. Only include precautions relevant to the procedure.

Plan how the results will be recorded and used

If the question asks how results will be recorded or processed, describe a table or graph that matches the variables. The independent variable normally belongs on the x-axis and the dependent variable on the y-axis. Include appropriate units, and show repeats separately before calculating a processed value such as a mean where appropriate. If the biological question requires a rate, percentage change or statistical comparison, state the processing that will make the data useful. Paper 5 may require students to choose appropriate mathematical or statistical methods, but the method must suit the type of data. Do not bolt a t-test, correlation test or chi-squared test onto an investigation simply because it sounds advanced.

Turn vague planning statements into operational ones

Strong planning statements include operational detail instead of relying on memorised practical phrases.

Common reasons planning answers lose marks

One common problem is a vague dependent variable. The answer says what is happening biologically but never states what will actually be measured. Another is naming a controlled variable without explaining how it will be standardised. Students also lose control of the answer when they give an arbitrary range, number of repeats or set of concentrations because they memorised it from a different experiment. The current syllabus asks whether the range and intervals are appropriate; it does not impose one fixed pattern across every investigation. Other weak plans omit apparatus detail, include an irrelevant control, use generic safety phrases, or describe a method that could not realistically be carried out. The best check is practical: could another student follow this method without having to guess what I meant?

A final Paper 5 planning check

Before moving on, check the plan against the question: independent variable identified and varied clearly? Dependent variable measurable? Key controls standardised? Apparatus and precision stated? Method in a logical order? Replication and data quality considered? Control experiment included only if appropriate? Risks identified specifically? Results recording or analysis described if asked?

Inside NeuraGeek, you can practise Paper 5 planning tasks and then use the marking guidance or AI Tutor to diagnose what is still vague. Ask not only "Did I mention repeats?" but "Did I explain why the repeats matter here?" Apply the same test to controls, apparatus, safety and data processing. Paper 5 rewards practical reasoning. Start from the biological problem, make every design choice serve that problem and give enough operational detail for the investigation to be carried out. Once you stop treating planning as a memorised template, unfamiliar questions become much easier to organise.