Earth’s distance from the Sun is one important reason it supports life. A planet’s atmosphere, pressure, temperature and history also matter. Being in a habitable zone does not automatically mean a planet is inhabited.

Scientists investigate Mars for clues to past water and possibly past life. Evidence for a once-habitable environment is not, by itself, evidence that organisms actually lived there.

Bacteria can divide into two cells. Hydra can produce buds. Suitable stem cuttings, potato buds (“eyes”) and ginger stems can grow into new plants. Not every detached plant part can form a whole plant.

Asexual offspring are usually genetically very similar to the parent, but changes in DNA can still occur. Repairing a cut is not automatically reproduction; a new individual must result.

Repairing, reusing and reducing unnecessary consumption can cut waste. Careful water and energy use, habitat protection, cleaner energy and well-designed farming all contribute. Students can observe, learn and work with adults on appropriate local actions.

Governments and organisations also have major responsibilities. The Montreal Protocol addresses ozone-depleting substances. The Paris Agreement aims to hold warming well below 2 °C above pre-industrial levels while pursuing efforts to limit it to 1.5 °C; it is not simply a promise of “below 1.5 °C.”