Health, Disease and Practical Skills
What you must understand
Distinguish communicable from non-communicable disease. Learn pathogens (bacteria, viruses, fungi, protists), how they spread, and defences: skin, mucus, cilia, stomach acid, white blood cells, antibodies and vaccination. Know examples such as cholera, malaria, HIV and antibiotic resistance. Understand risk factors for cancer, heart disease and diabetes.
Practical skills run through the whole paper. Know how to write a hypothesis, identify variables (independent, dependent, controlled), design controls, use apparatus safely, record results in tables, plot graphs, describe trends, calculate means and rates, and evaluate reliability and validity. Learn the difference between accuracy, precision and reliability.
Traps examiners set
- Saying antibiotics treat viruses.
- Confusing independent and dependent variables.
- Describing a trend without quoting data from the graph.
- Forgetting to repeat readings or control variables when asked to improve reliability.
Worked rule of thumb
For any experiment question, use the mnemonic "CHANGE, MEASURE, CONTROL": what you change, what you measure, what you keep the same. Then add repeats and a control group to improve reliability and validity.