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SAI International School
Subject- Biology, Class-VIII
Topic- Microorganisms: Friend and Foe
Subtopic- Disease-causing Microorganisms in Animals
and Plants, Food Poisoning

Module- 15
Lesson Notes

Disease-causing microorganisms in animals: The microorganisms cause many
diseases in animals as well. Robert Koch discovered a bacterium called Bacillus
anthracis which causes respiratory disease anthrax in humans and animals.

Foot and mouth disease of cattle is caused by a virus.

Disease-causing microorganisms in plants: Microorganisms cause diseases in
plants and yield of such crops is reduced. Certain chemicals are used to kill the
microorganisms. Some common plant diseases caused by microorganisms are as
below -

Plant diseases Microorganism Mode of Figures
transmission
Citrus canker Bacteria Air

Rust of wheat Fungi Air, Seeds

Yellow vein Virus Insects
mosaic of Bhindi