Identify algal pigments from Rf values and absorption spectra, then plan and analyse a coloured-light photosynthesis experiment with algal beads. Read the question, answer each part on paper, then work through it below and see how many of the 21 marks you would earn. The worked example shows a full-mark answer with the mark scheme point each line scores.
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Identify the independent and dependent variables exactly as they apply to this investigation, and name standardised variables with how each is kept the same.
A method in a logical order that someone else could follow: how the independent variable is changed (with values), how the dependent variable is measured, replicates, controls and a risk assessment that fits the procedure.
Processed values to a consistent number of decimal places, tables with units in the headings, graphs with labelled axes, points joined with ruled lines or a line of best fit as the data need, and error bars when asked.
Say whether the data support the hypothesis using the actual figures, choose the right statistical test, state the null hypothesis and interpret the result against the critical value.
The question on this page is rephrased from a Cambridge International past paper for teaching. The figures, wording of the workout and the worked example are our own; the marking follows the published mark scheme. The original question paper is available from Cambridge.