Assessed mathematical skills and measurement conventions

Recognise and use appropriate units in calculations, including converting units such as mm³ to cm³ in volumetric calculations and determining units for rates such as breathing rate.

Recognise and use decimal and standard form; choose appropriate decimal places; calculate with ordinary and standard form; apply standard form to organelle sizes; convert between forms while retaining significant figures, for example 0.0050 mol dm⁻³ = 5.0 × 10⁻³ mol dm⁻³.

Use ratios, fractions and percentages, including percentage yields, surface-area-to-volume ratios, measurement scales and phenotypic ratios in monohybrid and dihybrid crosses.

Estimate results to sense-check whether calculated values are appropriate.

Use calculators to find and use power, exponential and logarithmic functions, including estimating bacterial population growth over time.

Know and convert between the SI prefixes kilo, centi, milli, micro and nano, as clarified by Pearson for International A Level Biology candidates.

Use an appropriate number of significant figures; report calculated results consistently with the precision of the raw data and the least accurate measurement.

Calculate arithmetic means from biological data, such as mean stomatal counts.

Construct and interpret frequency tables and diagrams, bar charts and histograms; use clear headings, units and consistent decimal places; select suitable formats and interpret biological tables and graphs such as enzyme-activity graphs and ECG traces.

Understand simple probability and use probability and chance appropriately, including in genetic inheritance.

Understand sampling principles for scientific data, including analysing randomly collected data and calculating an index of diversity to compare habitats.

Understand and calculate or compare the mean, median and mode of biological datasets.

Use scatter diagrams to identify correlations between variables, for example between lifestyle factors and health.

Make order-of-magnitude calculations, including manipulating magnification = image size ÷ real-object size.

Select and use statistical tests, including chi-squared tests for observed versus expected results, Student's t-tests and correlation coefficients.

Understand measures of dispersion, including range and standard deviation; calculate standard deviation and judge when it is more useful, including when data contain an outlier.

Identify measurement uncertainties and use simple techniques to determine uncertainty when data are combined, including calculating percentage error.

Understand and use the symbols =, <, ≪, ≫, >, ∝ and ~.

Change the subject of an equation and manipulate equations in biological contexts such as magnification.

Substitute numerical values into algebraic equations using appropriate physical units, including using a supplied formula to calculate an index of diversity.

Solve algebraic equations in biological contexts, for example cardiac output = stroke volume × heart rate.

Use logarithms for quantities spanning several orders of magnitude, including logarithmic scales for microorganism growth.

Translate information between graphical, numerical and algebraic forms, including using data represented by dissociation curves.

Plot two variables from experimental or other data and select appropriate formats such as bar charts, histograms, graphs and scattergrams.

Understand that y = mx + c represents a linear relationship and predict or sketch linear graphs in biological contexts.

Determine a graph intercept, including reading an intercept such as the compensation point in plants.

Calculate rate of change from a graph showing a linear relationship, for example transpiration rate.

Draw and use the slope of a tangent to a curve as a measure of rate of change, such as product formation at a point on an enzyme-reaction curve.

A.4.1—Circumference, area and volume

Calculate circumferences, surface areas and volumes of regular shapes, including circles, rectangular and cylindrical prisms and spheres, and apply these calculations to cells.