Practical Skills and Mathematical Requirements | OCR A-Level Biology A (H420)
Practical Skills and Mathematical Requirements
- 104 questions
- 6 subtopics
- Module 1: Development of practical skills in biology
- Component 01, Component 02 and Component 03
Practical skills and mathematical requirements is module 1 and the maths the specification expects, assessed on every paper.
It covers planning investigations and choosing apparatus, recording and presenting data, reading gradients, intercepts and logarithmic scales, averages, standard deviation and statistical tests, evaluating experiments and uncertainty, and estimates and biological calculations.
Sample questions from Practical Skills and Mathematical Requirements
Answer each one closed book first, then open the answer.
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Planning investigations and choosing apparatus
Why are repeat readings taken at each value of the independent variable?
Show the answer
Repeats allow a mean to be calculated, anomalous readings to be spotted, and the spread of the results to show how precise the data are. -
Planning investigations and choosing apparatus
What ethical requirements apply when people are the subjects of a physiological investigation such as measuring pulse rate?
Show the answer
Participants must give informed consent, be free to withdraw at any time and have their data kept anonymous, and anyone at risk, such as a person with a heart condition, must be excluded from exercise. -
Recording and presenting data
Round 0.004872 mm to 2 significant figures.
Show the answer
0.0049 mm: the leading zeros are not significant, so the first two significant figures are 4 and 8, and the following 7 rounds the 8 up to 9. -
Recording and presenting data
When should data be presented as a histogram?
Show the answer
When one continuous variable, such as leaf length, is grouped into classes and the frequency of each class is shown; the bars touch because the classes run on from each other. -
Gradients, intercepts and logarithmic scales
What shape of graph is expected for rate of reaction against substrate concentration when enzyme is in excess, and why?
Show the answer
A straight line through the origin, because spare active sites are always available, so the rate rises in proportion to substrate concentration. -
Gradients, intercepts and logarithmic scales
Why is a logarithmic scale used to plot the number of cells in a microbial culture?
Show the answer
Cell numbers rise over several orders of magnitude, from hundreds to billions, which cannot be shown on a linear scale; a log scale gives each tenfold increase an equal step. -
Averages, spread and statistical tests
State the formula for standard deviation used in A Level Biology.
Show the answer
s = √[Σ(x − x̄)² ÷ (n − 1)], where x is each value, x̄ is the mean and n is the number of values. -
Averages, spread and statistical tests
When is an unpaired Student's t-test used?
Show the answer
To test whether the means of two independent sets of normally distributed data, such as leaf lengths from plants in sun and in shade, are significantly different.
The 6 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Planning investigations and choosing apparatus | Recall questions on independent, dependent and control variables, controls, valid methods, the range and number of values to test, choosing apparatus, risk assessment, and the ethical use of living organisms and people. | 16 |
| Recording and presenting data | Recall questions on laying out results tables with units in the headings, decimal places and significant figures, standard form and unit conversions, the units of a rate, and choosing bar charts, histograms and line graphs. | 17 |
| Gradients, intercepts and logarithmic scales | Recall questions on calculating rates from gradients, y = mx + c, drawing tangents to curves, intercepts and the compensation point, extrapolation, and why logarithmic scales are used for microbial growth. | 15 |
| Averages, spread and statistical tests | Recall questions on the mean, median, mode and range, calculating standard deviation, correlation and causation, and choosing and interpreting the t-test and Spearman's rank correlation coefficient. | 19 |
| Evaluating experiments and uncertainty | Recall questions on anomalous results, accuracy and precision, repeatable and reproducible results, random and systematic errors, the uncertainty of analogue and digital readings, percentage error, limitations, improvements and conclusions. | 18 |
| Estimates, symbols and biological calculations | Recall questions on estimating results and orders of magnitude, the symbols <, >, ≪, ≫, ∝ and ~, offspring probabilities, microbial population growth, magnification, and surface area to volume ratios. | 19 |
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 sections
OCR A-Level Biology A Active Recall Guide
Every section, not just this one. 1,833 questions with their answers.