Graphs, Tables and Units for IGCSE Biology Practicals
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Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
What this skill means
Put the independent variable on the x-axis and dependent variable on the y-axis, label both with units, use a sensible scale covering most of the grid, plot small precise points and draw the appropriate best-fit line or curve.
Graph and table marks are procedural. A correct biological conclusion cannot recover marks lost through missing units, poor scale or inconsistent precision.
Build a scoring graph
Place the independent variable on the x-axis and the dependent variable on the y-axis. Label each axis as quantity / unit, choose a linear scale using more than half the grid and plot small crosses accurately. Draw a ruled line of best fit or smooth curve as appropriate; do not join every point dot-to-dot unless instructed.
Write a clear results table
Put the unit in the heading rather than after every number. Keep decimal places consistent within a column and match the precision of the measuring instrument. Record raw observations before calculated values.
Handle anomalies and means
An anomalous result does not follow the overall pattern. Identify the exact value, repeat it where possible and decide whether to exclude it from the mean. Never remove a point merely because it makes the graph less neat.
Percentage change and rate
Percentage change = (final − initial) ÷ initial × 100. A negative answer indicates a decrease. When the same fixed change is timed, rate can be calculated as 1 ÷ time. Include units where the calculated quantity has them.
Use this before submitting your answer
A complete answer is specific enough for another person to repeat or assess.
✓Independent variable on x-axis; dependent variable on y-axis.
✓Both axes labelled with quantity and unit.
✓Sensible scale using most of the grid.
✓Small accurate points and suitable best-fit line.
✓Consistent table precision and units in headings.
✓Correct calculation method with working shown.
Try the skill in a question (4 marks)
State four features of a correctly plotted line graph for an enzyme experiment.
Show the answer and marking guidance
Independent variable on the x-axis and dependent variable on the y-axis.
Axes labelled with quantities and units.
Sensible linear scale using more than half the grid.
Points plotted accurately with a suitable best-fit line or curve.
Original practice content written for this site. It is not an official Cambridge question.