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Exposure, infection and disease

Exposure, infection and disease

Flow diagram showing respiratory, digestive, skin and urogenital entry routes converging on entry, defence evasion, attachment, replication and disease

A pathogen is a biological agent that can cause disease. Exposure alone is not the same as infection, because infection begins only if the pathogen enters the body and multiplies.

Bacteria, viruses and pathogen entry Lesson

  1. A Level
  2. /Biology
  3. /Bacteria, viruses and pathogen entry

Step-by-step lessons covering Edexcel A A Level Biology Bacteria, viruses and pathogen entry for A Level Biology. Each lesson works through exam-style questions in Paper 1, Paper 2 and Paper 3 format. Build a strong foundation in cell biology and biochemistry early on, since later topics on genetics, ecology and physiology all draw on these core concepts.

Lessons