Presenting and interpreting biological data
Biology · Key Stage 3 · The School
Matching the chart to the data
CONTINUOUS data can take any value, like height, temperature or time. It usually suits a LINE GRAPH, especially where you change one thing and measure another across a range. CATEGORIC data is separate, named groups with no order between them, like blood type or plant species. It suits a BAR CHART, with a gap between the bars to show they are not continuous.
Spotting an anomalous result
An ANOMALOUS result sits well outside the pattern the rest of the data shows. It is usually caused by a slip in measurement or a fault in the equipment, not by the biology itself. The right response is to repeat that one measurement, if you can. Do not just delete the awkward number, and do not quietly fold it into an average.
Describing a trend, with a reason
A strong description of a trend states the PATTERN exactly. For example: "reaction time rose as temperature fell, but levelled off below 10°C." Then it gives a likely biological REASON for that pattern. Naming a trend with no reason loses marks. So does giving a reason that does not actually match the pattern in the data.
An experiment counts gas bubbles from pondweed each minute, at six equal steps of rising light: 2, 5, 9, 14, 15, 15. First, pick the chart. Light intensity is continuous, so a line graph fits. Next, check for anomalies. None of these six values sits wildly outside a sensible pattern, so none needs repeating. Last, describe the trend with a reason: "the rate rose steadily up to the fourth reading, then levelled off. Some other factor — likely carbon dioxide or temperature — became the limit instead of light." That last sentence is the one a mark scheme actually wants. The first two steps are what make it possible to write it honestly.