In this module, you will learn:

  • microorganisms such as bacteria, fungi and viruses
  • the uses of bacteria and fungi
  • the harmfulness of bacteria, fungi and viruses

Resources to help you:

  • Textbook: page 45
  • Notebook: page 26

Watch the video

See how the blood flows between the heart and the lungs


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You will need a microscope to be able to see some microorganisms

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Microorganisms are living things that are very small. They cannot be seen with our naked eyes. We need a microscope to be able to see them.

There are three (3) groups of microorganisms that we will be looking at:

  1. Bacteria
  2. Fungi
  3. Viruses



Bacteria are organisms that is made up of only one cell. They can be found anywhere including some of the most extreme places such as in volcanoes.

There are some bacteria that are useful. For example, bacteria in the soil helps to decompose the dead plants and animals into useful nutrients in the soil. Bacteria are also used to make cheeses and yoghurts.

Some bacteria are harmful. They cause diseases that can kill people. Some of the diseases that they can cause are tuberculosis, cholera, tetanus, and meningitis.

Scientists grow bacteria in petri dishes to study them

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Vibrio Cholerae Bacteria causes Cholera

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Amanita muscaria, commonly known as the fly agaric

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Decomposing tomato with mould growing

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Fungi are neither plants nor animals. They include living things such as mushrooms, moulds, and yeasts.

Fungi do not have roots, stems or leaves. They cannot undergo photosynthesis to make food so they are not classified as plants.

Some fungi feed on dead matter while some feed on living plants and animals.

Fungi can be useful. Yeast is a fungi that is used to make bread. Some mushrooms can be eaten as food.

There are also fungi that are harmful. They cause diseases such as athletes' foot and ringworm.



Viruses are extremely small. They cannot be seen even with a light microscope. To see viruses, we need an electron microscope.

Viruses are harmful because they cause diseases. Some of the diseases that are due to viruses are the common cold, influenza, measles, and AIDS.

The current pandemic is caused by a virus known as SARS-Cov-2 which stands for severe acute respiratory syndrome coronavirus 2 .

The influenza virus causes the flu

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A 3D model of a virus

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