IGCSE BIOLOGY: The 7 Life Processes Just think: MRS GREN
Living or not?
Usually it's pretty obvious whether something is living or non-living. A dog is living, a rock is not. But sometimes the line is a little blurred. Viruses, for example, are not considered living, even though they behave like living things in some ways.
We can decide if something is living based on whether or not it does all 7 life processes. These are:
- Move
- Respire
- Sense things
- Grow
- Reproduce
- Excrete
- Need nutrition
To remember these 7 words just think of the name: MRS GREN
Move
An action by an organism or part of an organism causing a change of position or place
Respire
The chemical reactions in cells that break down nutrient molecules and release energy for metabolism
Remember the equation for aerobic respiration:
Glucose + Oxygen --> Carbon Dioxide + Water
Sense
The ability to detect or sense stimuli in the internal or external environment and To make appropriate responses
Different organisms sense in different ways but examples include seeing, hearing, recognising temperature changes etc.
Grow
A permanent increase in sizE And dry mass by an increase in cell number or cell size or both
Reproduce
THE PROCESS THAT MAKES MORE OF THE SAME KIND OF ORGANISM
Excrete
The removal from organisms of waste products of metabolism (chemical reactions in cells including respiration), toxic materials, and substances in excess of requireMents.
Humans excrete waste products in urine as well as releasing carbon dioxide via the lungs. Excretory products are only those produced through metabolic process.