A pattern, not one test
Living things are made of one or more cells. They use energy and materials, produce waste, respond to their surroundings, grow and reproduce. Look for the collection of characteristics, not just one.
What does it mean to be living?
Look for patterns in the characteristics of living things.
Class notes
Open PDF →Energy and metabolism
Plants capture light energy; animals obtain energy from food. Metabolism describes the chemical processes in an organism that build, break down and transform materials.
Response and reproduction
A plant bending toward light is responding to its environment. Reproduction maintains a population over generations; an individual organism does not have to reproduce to be alive.
Explore the idea
01Organization
Living things are made of one or more cells.
02Energy and materials
Living things use energy and exchange materials with their surroundings.
03Growth and response
Living things grow and respond to changes; individual characteristics must be considered together.
Explore this idea further
Watch: Characteristics of life · Amoeba Sisters
Look for patterns in the characteristics of living things.
Open on YouTube →A fire uses fuel and grows. Is that enough to call it living?
Reveal the reasoning
No. A fire is not made of cells and does not carry out the full set of life processes.
Try it yourself.
A flame grows and uses fuel. What evidence would you need before calling it living?
Check your thinking
Growth and fuel use alone are insufficient. Fire is not made of cells and does not carry out the full set of life processes.
Common question: Do all living things move from place to place?
No. Many plants remain rooted but still grow and respond to stimuli.
Take it further.
Compare a dormant seed and a rock. What observations could help distinguish them?
See a possible explanation
A seed can germinate under suitable conditions and is made of cells; a rock does not carry out life processes.