Edexcel IGCSE Biology (Triple Award) Past Papers

Common mistake: : Students often provide a biological reason when asked only to "describe" a trend, or they simply state what the data shows when the command word is "explain".

How to solve it: Identify the command word first. "Describe" means stating what is happening (e.g., "as temperature increases, the rate of reaction increases"). "Explain" requires you to state why it is happening using biological knowledge (e.g., "because enzymes have more kinetic energy and collide more frequently").

Common mistake: Confusing the independent variable (what you change) with the dependent variable (what you measure) or failing to list relevant control variables.

How to solve it: Use the CORMS prompt to plan investigations: Change (Independent), Organism, Repeat, Measure (Dependent), and Standardise (Control). Ensure your control variables are abiotic factors relevant to the specific experiment, like light intensity or pH.

Common mistake: Stating that random placement of quadrats improves "reliability" (it actually improves validity by reducing bias) or suggesting that repeating an experiment at different values improves reliability.

How to solve it: Reliability is improved by repeating measurements at the same values and calculating a mean. Validity is improved by controlling all other variables so that only the independent variable affects the results

Common mistake: Mixing up terms that sound alike, such as "lactase" (enzyme) vs. "lactose" (sugar), "mitosis" vs. "meiosis," or "antigen" vs. "antibody".

How to solve it: Be extremely careful with spelling. Phonetic spelling is generally accepted unless the word could be mistaken for a different biological term. For example, confusing "lactase" and "lactose" will result in a lost mark.

Common mistake: Drawing arrows in the wrong direction or failing to start the chain with a producer.

How to solve it: Ensure arrows point in the direction of energy flow (from the organism being eaten to the organism eating it). Every food chain must begin with a producer (usually a green plant).