Microbiology - pathogens
microorganisms are things that are too small to be seen by the naked eye, They can only be seen through microscopes.
Pathogens cause infectious diseases. some bacteria, virus and fungi are pathogens.
However some bacteria and fungi are useful and can be used to make yoghurt, bread, antibiotics and beer.
food production using yeast
Yeast is a single celled organism.
It is used to make bread and alcoholic drinks.
Yeast is respires aerobically (with oxygen) and anaerobically (without oxygen).
The anaerobic respiration of yeast produces alcohol (and carbon dioxide), this is known as fermentation.