Meet unfamiliar evidence
with a method.

When you are given a graph, table or other data question, work through it in this order. Focus on what the data shows before looking at the answer choices.

1. Understand the figure.

   Start with the axes or column headings. Identify:

   • what the scientists changed;
   • what they measured;
   • the units used.

   On a graph, the variable that was changed is usually on the x-axis. The variable that was measured is usually on the y-axis.

2. Describe the pattern.

   Look for where the pattern changes. Divide the data into sections if necessary, then describe what happens in each one: does it increase, decrease or stay roughly the same?

   Support each statement with values and units. For example: “As temperature increases from 0 °C to 20 °C, the rate increases from 10 to 44 arbitrary units. Between 20 °C and 40 °C, the rate remains approximately constant.”

   Whenever possible, calculate the size of the change. If the effect is different in different parts of the figure, compare them. For example, calculate the change at both a lower and a higher temperature rather than simply stating that membrane fluidity changes.

3. Be careful when explaining causes.

   First describe what the data shows. Only say that one variable caused a change when it was the only variable altered and the other relevant conditions were controlled.

   If two variables change together but the investigation does not establish cause and effect, describe them as being associated or correlated. Do not assume that one caused the other.

4. Complete calculations carefully.

   Use the exact data points named in the question, even if nearby values are easier to read.

   For percentage change:

   percentage change = (final value − starting value) ÷ starting value × 100

   Remember:

   • the starting value is the value you divide by;
   • include a minus sign if the value decreased;
   • in a written response, state clearly that the result represents a decrease or loss;
   • if the answer box requests a number only, do not include words or units.
5. Choose the right practice activity.

   If you are learning how to interpret graphs and tables, begin with Data Analysis Introduction. You can practise these skills without needing detailed knowledge of a Biology topic.

   Then choose the course section that matches your study:

   • AS Level: Units 1–3
   • A Level: Units 4–6
   • Year 12: You may also use the A Level activities

   Within each skill, work through the levels in order: Intro → Secure → Challenge.

   Read the guidance above each question before answering. You can use the worked solution to check your method, but try the question yourself first. Complete the activity by answering both questions correctly in your own attempt.