Interpreting Graphs 10

Exam questions about graphs use different command words, and each needs a different type of answer.Describe means say what the graph shows. Give the overall trend, note any change in trend (for example where the line levels off or peaks), and quote data from the graph with units.Explain means give biological reasons for the trend. Use scientific ideas such as active sites, enzyme-substrate complexes, limiting factors or water potential.Calculate means work out a value. Show your working and give units.Evaluate means consider evidence for and against a conclusion, for example sample size, error bars, whether other variables were controlled, and whether correlation shows causation.Example (describe): "As substrate concentration increases from 0 to 10 mmol dm^-3, the rate increases; above 10 mmol dm^-3 it levels off at 50 units." Example (explain): "At high substrate concentrations all active sites are occupied, so enzyme concentration is limiting."