Micro-organisms or microbes are microscopic living things including:

1. A What are microbes? Micro-organisms or microbes are microscopic living things including: • bacteria • fungi (which may be visible without a microscope) • viruses • protozoa • algae.

2. Most microbes are helpful: • Soil microbes break down dead plant and animal material, recycling nutrients. • Bacteria help herbivores to digest grass. • Algae in the sea form the beginning of thefood chain while also providing much of the oxygen we breathe. • Microbes also help produce foods such as bread, cheese, yoghurt and wine.

3. A few microbes cause disease in plants or animals. Disease-causing microbes are called pathogens. • Diseases caused by bacteria include cholera, tuberculosis, whooping cough and food poisoning. • Diseases caused by viruses include measles, influenza, AIDS and the common cold. • Diseases caused by fungi include athlete’s foot, ringworm and thrush. • Malaria and giardia are both caused by protozoa.

4. What are microbes? Microbes are microscopic organisms including bacteria, fungi and viruses. Most microbes are helpful, performing essential functions such as decomposing dead plant and animal remains, helping to digest food, and making food such as cheese and yoghurt. A few microbes cause disease. They are called pathogens. • Tuberculosis and food poisoning are caused by bacteria. • Measles and influenza are caused by viruses. • Athlete’s foot and ringworm are caused by fungi. 6A 1 Microbes: the good and the bad

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