Biology can be defined as the science that studies living organisms and how they interact with their environment.
All living things must carry out all of the following:
Respiration: - releases energy from food for use by cells.
Excretion: - removal of waste products of chemical reactions (metabolism).
Movement: - animals move from place to place to avoid predators and to search for food, while plants move parts of themselves to prevent damage and during growth.
Irritability (response to stimulus): - sense changes in their environment and respond to them. This helps them to detect danger and increases their chance of survival.
Nutrition (feeding): - plants make their own food while animals obtain food from their environment. This provides energy for them to carryout all the important processes in their body.
Development and Growth: - is a permanent increase in size and complexity, which ensures organisms have systems in place to perform specific functions.
Reproduction: - making of new offspring to ensure continuation of the species. This can be done sexually or asexually.
N.B. To help you remember, the characteristics spell the acronym R.E.I.N.D.e.R.