1. Unit 2:1 Characteristics of living Organisms
Living organisms have a set of seven characteristics that make them different from non-living things.

2. Unit 2:2 Micro-organisms
A micro-organism is a living organism so small that we can only see it when we use a microscope.
Micro-organisms are made of cells, like all living organisms. Most micro-organisms are made of only one cell.
There are several groups of micro-organisms.
Bacteria: Bacteria are found everywhere. Their cells are much smaller than human cells. You could line up 1,000 of these bacteria, end to end, between two millimetre marks on a ruler.
Microscopic Fungi: Many fungi, including mushrooms and toadstools, are large. However, there are also some microscopic ones. Yeast, for example is a single-celled microscopic fungus.
Single-celled algae and protozoa: If you are able to look at some pond water under a microscope, you will see many tiny living organisms. Some of them are tiny plant-like organisms called algae. Some of them are one-celled animals, called protozoa.