Analysing and Evaluating Practical Results | OCR A-Level Biology B (Advancing Biology) (H422)
Analysing and Evaluating Practical Results
- 95 questions
- 6 subtopics
- Practical skills, examined on all three papers
- Component 01, Component 02 and Component 03
Analysing and Evaluating Practical Results is examined in all three written papers — the specification states that Components 01, 02 and 03 can each assess content from any of the five modules, so nothing is confined to one paper.
It covers processing and interpreting experimental results, Mathematical skills for analysing biological data, significant figures and reporting values, plotting and interpreting graphs, anomalies, limitations and refining a procedure and precision, accuracy and uncertainty.
Sample questions from Analysing and Evaluating Practical Results
Answer each one closed book first, then open the answer.
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Processing and interpreting experimental results
A student records the time taken for a colour to disappear. Explain how this is converted into a rate.
Show the answer
The rate is calculated as one divided by the time, so a shorter time gives a larger rate. -
Processing and interpreting experimental results
A student tests one enzyme and concludes that enzymes work best at 40 °C. Explain why the conclusion is faulty.
Show the answer
Only one enzyme was investigated, so the result can be stated for that enzyme alone and not for enzymes in general. -
Mathematical skills for analysing biological data
How are the degrees of freedom found for a chi-squared test?
Show the answer
They are one fewer than the number of categories of data. -
Mathematical skills for analysing biological data
A t-test on two samples of 10 gives t = 3.16, and the critical value for 18 degrees of freedom at p = 0.05 is 2.10. What does this show?
Show the answer
Because 3.16 is greater than 2.10, the difference between the two means is significant at the 5% level, so the null hypothesis of no difference is rejected. -
Significant figures and reporting values
Round 0.048372 to two significant figures.
Show the answer
It rounds to 0.048. -
Significant figures and reporting values
Explain why a percentage calculated from practical data should not be quoted to five decimal places.
Show the answer
The precision of the raw measurements does not justify it, so the extra figures carry no meaning. -
Plotting and interpreting graphs
When is it acceptable for a graph axis not to begin at zero?
Show the answer
When all the values lie within a narrow band well above zero, provided the break in the axis is clearly shown. -
Plotting and interpreting graphs
When should a line of best fit be drawn through the origin?
Show the answer
Only when a zero value of the independent variable is known to give a zero value of the dependent variable; otherwise the line is fitted to the plotted points alone.
The 6 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Processing and interpreting experimental results | Recall questions on processing raw data, qualitative and quantitative results, making a Benedict's test semi-quantitative, converting time into rate, valid conclusions and the limits of extrapolation, correlation and causation, and calculating and interpreting percentage change in mass of potato tissue. | 13 |
| Mathematical skills for analysing biological data | Recall questions on the mean, median, mode and range, standard deviation and error bars, choosing and calculating the t-test, chi-squared test and Spearman's rank correlation coefficient, degrees of freedom and p = 0.05, Simpson's index, logarithmic scales, magnification, estimation, and surface area and volume. | 30 |
| Significant figures and reporting values | Recall questions on counting significant figures in small and standard-form values, the rule for a calculated result, rounding practical data sensibly, and decimal places versus significant figures. | 12 |
| Plotting and interpreting graphs | Recall questions on axis choice, scales and when zero may be omitted, taking a gradient from a line or a curve, anomalous points, and what an intercept shows. | 14 |
| Anomalies, limitations and refining a procedure | Recall questions on identifying and dealing with anomalous results and their causes, limitations of procedures such as potometers and counting bubbles, and refinements including gas syringes, repeats, colorimeters and data loggers, and consistent rest periods in pulse rate studies. | 13 |
| Precision, accuracy and uncertainty | Recall questions on accuracy and precision, the uncertainty of measuring instruments, calculating percentage error for thermometers, measuring cylinders and burettes, why larger measurements carry smaller percentage errors, and random and systematic errors such as zero errors. | 13 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR A-Level Biology B (Advancing Biology) Active Recall Guide
Every topic, not just this one. 2,895 questions with their answers.