Cambridge IGCSE Biology: Core Topics and How to Revise Them

Cambridge IGCSE Biology is studied at South African schools offering the international Cambridge pathway. Whether you are in the Core or Extended tier, the subject covers a wide range of biological content and demands both factual recall and the ability to apply knowledge in unfamiliar contexts.

This guide focuses on the highest-value topics and how to revise them effectively.

Understanding the Assessment Structure

Cambridge IGCSE Biology (0610) has three assessment components:

• Paper 1: Multiple choice (40 marks, 45 minutes)
• Paper 2: Core theory (80 marks, 1 hour 15 minutes) — for Foundation tier
• Paper 3: Extended theory (80 marks, 1 hour 15 minutes) — for Extended tier
• Paper 5 or 6: Practical or alternative to practical

Students targeting A* or A will write Paper 3 (Extended). The Extended paper covers all Core content plus additional material and asks more complex application questions.

The Highest-Value Topics

Cell biology and organisation is fundamental to everything else. Know:

• The differences between animal and plant cells (and bacterial cells)
• Functions of each cell organelle
• Osmosis, diffusion, and active transport — definitions, processes, and factors affecting them
• Levels of organisation from cells to organisms

Questions on cell processes (osmosis especially) appear on almost every paper and require you to predict outcomes in new situations — not just define the terms.

Enzymes and digestion — Cambridge tests enzyme function deeply:

• The lock-and-key and induced-fit models
• The effect of pH, temperature, and substrate concentration on enzyme activity
• Interpreting graphs showing enzyme activity (including denaturation)
• The digestive system: organs, enzymes produced, substrates, and products

Enzyme questions almost always include a graph or experiment that you must interpret. Practise reading and annotating enzyme activity graphs until the patterns are instinct.

Respiration and gas exchange — both aerobic and anaerobic respiration are tested:

• Word and chemical equations for both types
• The structure of the lungs and how gas exchange occurs
• Comparing lung structure in different organisms

Know the exact wording of both respiration equations. Cambridge mark schemes often require specific terminology.

Transport in plants and animals — xylem, phloem, and the human circulatory system:

• Structure and function of xylem and phloem
• Transpiration and its factors
• The heart and circulatory system (including the cardiac cycle)
• Blood components and their functions

Genetics and inheritance — the most mark-dense theoretical section:

• DNA structure and replication
• Mitosis and meiosis (differences and outcomes)
• Monohybrid and dihybrid crosses
• Codominance, sex-linkage, mutation

Cambridge genetics questions regularly include Punnett squares and require you to calculate ratios and predict phenotype frequencies.

Practical and Experimental Skills

Cambridge IGCSE Biology places significant emphasis on experimental skills. Even in the alternative-to-practical paper, you are expected to:

• Design experiments with controls and variables
• Process results (calculate means, plot graphs)
• Evaluate experimental design (identify sources of error, suggest improvements)

Practise these skills with past Paper 5 or Paper 6 questions. Many students who are strong in content underperform on practicals because they have not practised the specific "design an experiment" and "evaluate the results" question types.

Using the Cambridge Syllabus

Download the IGCSE Biology syllabus from the CAIE website and work through the learning outcomes systematically. Each bullet point in the syllabus is a potential exam question. Students who can confidently address every syllabus point are fully prepared for the theory papers.

Past papers from the Cambridge resources, alongside the Examslayers past papers section, give you the practice and mark scheme analysis you need.