Living things have certain life processes in common. There are seven things that they need to do to count as being alive. The phrase MRS GREN is a way to remember them:
| M |
Movement |
|
| R |
Respiration |
Getting energy from food |
| S |
Sensitivity |
Detecting changes in the surroundings |
| G |
Growth |
|
| R |
Reproduction |
Making more living things of the same type |
| E |
Excretion |
Getting rid of waste |
| N |
Nutrition |
Taking in and using food |
It can be easy to tell if something is living or not. A teddy bear might look like a bear, but it can't do any of the seven things it needs to be able to do to count as being alive.
Were these bears living when they were photographed?
What about a car? A car can move, it gets energy from petrol, it might have a car alarm, it needs petrol and it gets rid of waste gases through its exhaust pipe. But it can't grow or make baby cars. So a car is not alive.
Have you ever seen a mother car with babies?
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