The eight characteristics
The characteristics generally accepted as marking something out as alive are eight. The rest of this chapter is eight sections, one for each.
| Characteristic | In short | Section |
|---|---|---|
| Cellular organization | Every organism is built of cells | 8.1 |
| Nutrition | Taking in energy and materials | 8.2 |
| Respiration | Releasing that energy from food | 8.3 |
| Irritability and co-ordination | Responding to stimuli | 8.4 |
| Excretion | Putting waste out of the body | 8.5 |
| Movement | The body, or part of it, moving | 8.6 |
| Reproduction | Producing a new generation | 8.7 |
| Growth and development | Getting bigger, and getting more complex | 8.8 |
How the list is used
Not everything showing one of the eight is alive — ripples on a reservoir move, a crystal "grows". But something showing several of them together is alive. So the list is not a test applied one item at a time; it is a picture taken all at once.
The next section starts with the first of them: the unit every organism is built from.