Living things have a few things in common, and these characteristics determine whether something counts as a living organism.
- Excretion – living things can get rid of unwanted materials.
- Growth – given the right conditions, living things can grow!
- Movement – we don’t mean that plants suddenly grow legs and start walking, but living things can change position. Plants can grow towards a light source and move from one place to another as seeds.
- Nutrition – humans, plants, and animals can all absorb nutrients. Humans and animals eat food to get nutrients, and plants absorb nutrients from the soil through their roots.
- Order – living things are made up of cells. Cells are the smallest unit of life, and each cell has its function or purpose. For example, the human body comprises over 30 trillion cells!
- Reproduction – living things have to be able to reproduce to make more of what they are. E.g., plants produce to create more plants; animals produce to make more animals, etc.
- Respiration – respiration is sometimes used as another word for breathing. Plants respire through photosynthesis.
- Sensitivity to their environment – living things has to be able to respond and adapt to their environments. So, for example, some animals can camouflage themselves to avoid predators!