Enzyme experiments are a fixture of 0610 Paper 6, and the marks follow the same pattern every time: read the apparatus, head and fill the table, spot the anomaly, draw the graph, explain the shape and judge the method. Read the foam height in each tube against its ruler, calculate the means, choose a scale and a line, then use enzyme biology to explain the rise and the fall. Every attempt uses a different potato, so the optimum and the readings change. Allow about 25 minutes.
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Every foam height read to the nearest millimetre against the ruler (1 small division = 1 mm, the numbers are centimetres), the anomalous trial identified by comparing it with its partner, each mean correct with the anomaly left out, and a column heading with the quantity and its unit: mean height of foam / mm.
A height scale that fits every point and uses more than half of the grid, the points joined by ruled lines or a smooth curve with no extrapolation, and a value read from your own line at the temperature asked.
The trend in two parts (a rise to the optimum, then a fall), the rise explained by kinetic energy and more frequent collisions with the active site, and the fall explained by a denatured active site. Enzymes are never “killed”.
The independent variable (temperature), the dependent variable (height of foam) and two variables that were standardised: the hydrogen peroxide and the potato discs.
A specific source of error (the uneven, bursting foam is hard to read), an improvement that really adds reliability (more repeats and a mean, anomalies left out) and a safety precaution tied to the hazard of hydrogen peroxide.
The marking follows the conventions in published Cambridge mark schemes. The experiments, readings and wording on this page are our own.