The body's defence systems
The body's defence systems
A pathogen is a microorganism that causes infectious disease. Pathogens include viruses, bacteria, protists and fungi.
Step-by-step lessons covering AQA GCSE Biology 3.1.6 Human defence systems for Foundation and Higher tier. Each lesson works through exam-style questions in Paper 1 and Paper 2 format. Start with the foundational topics and build up to the higher-tier material.