01
A biosignature is an observable feature whose presence or abundance may indicate biological activity, but robust interpretation requires ruling out plausible abiotic alternatives.
supportedLearn this concept
Turn the idea into understanding.
Knowledge map
See where this idea fits.
Before this
Prerequisites
After this
Builds toward
Evidence first
Verified knowledge behind the lesson.
02
Life can alter an environment by producing gases faster than nonbiological processes remove them, maintaining strong chemical disequilibrium, fractionating isotopes, or generating complex structures.
supported03
Earth provides the only confirmed biosphere for calibration.
supported