Lesson 1 of 11 · 6 min

Microbes all around

NCERT §8 (chapter introduction)

Ananya opens her diary on Sunday night with a question her biology teacher left on the board: if microbes are everywhere, why are we still alive, and well?

The story this chapter follows: Ananya's microbe diary

Ananya, a Class 12 student in Mysuru, keeps a diary for one week of every place microbes work for her family: her grandmother's curd, the breakfast dosa, her brother's antibiotics, the kitchen packets, a school visit to the city sewage treatment plant, and a weekend at her uncle's farm with its 12-foot-deep gobar gas tank, cabbage rows and paddy field. Each day is one part of this chapter.

The lesson in notes

In short

Microbes are major parts of every biological system, alongside the large plants and animals. They live in soil, water and air, and inside the bodies of humans, other animals and plants.

They survive where nothing else can: inside geysers (thermal vents) at temperatures up to 100°C, deep in the soil, under snow many metres thick, and in strongly acidic places.

The microbial world is varied: protozoa, bacteria, fungi, microscopic plant and animal viruses, viroids, and prions, which are infectious agents made of protein.

Bacteria and many fungi grown on nutritive media form colonies large enough to see without a microscope; such cultures are used to study micro-organisms.

Microbes cause many diseases of humans, animals and plants, but most are not harmful, and many serve human welfare in several ways.