microorganisms are friend or foe give four points in each case to support your answer
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Microorganisms – friend or foe?
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We can’t see them. We can’t hear them or feel them, but they are with us. There are 10 trillion (10 x 1,000,000,000,000 or a million million) cells in the average body. For every cell, we have 10 times as many microorganisms – that’s 100 trillion microorganisms on and in our bodies! We are a walking, talking ecosystem.
But don’t worry – without microorganisms, we wouldn’t survive.

Hookworm
A hookworm is a parasite that can live in the human body.
Acknowledgement: CDC – National Center for Infectious Diseases
Microorganisms are small
A microorganism is a living organism that is so tiny it can only be seen with the aid of a microscope.
Consider that the largest human cells are about the diameter of a human hair. Bacteria cells are one-hundredth the size of a human cell and viruses are much, much smaller again. If you imagine that a single virus was the size of an adult human, a bacterium (single cell) would be over 10 storeys high by comparison. A bacterium next to a human cell is like a tiny boat next to a big ship. Hundreds of thousands of bacteria could fit onto a pinhead.
Friend and foe
The main microorganisms in and on our bodies are protozoa, algae, fungi, bacteria and viruses. Most microorganisms are beneficial, for example, there are microorganisms in our large intestine that synthesise vitamins and allow them to be absorbed into the bloodstream. However, a tiny minority are pathogens (disease-causing agents). These pathogens, often called germs or bugs, are a threat to all life forms.
Let’s take a closer look at bacteria, viruses and parasites.