The big picture
Life lives on a layer as thin as an apple's skin. Nine ideas explain why it can, and how it continues.
| Idea | Remember | Example |
|---|---|---|
| A place in the middle | Right distance: water stays liquid | Closer, it boils. Farther, it freezes |
| The blanket of air | Gravity keeps air. Ozone blocks UV | Mars has thin air |
| Water everywhere | About 70 per cent of the surface | The hydrosphere |
| The thin layer on top | Soil comes from rock and dead matter | Nitrogen and potassium |
| The neighbours | Distance and air decide the heat | Venus is the hottest |
| Several at once | Distance, size and magnetic field | Lose one, life is at risk |
| Looking after Earth | Burning fuel warms the planet | Use less fuel |
| One parent or two | One parent: young match it. Two parents: a mix | Potato eye; seed |
| Flower to seed | Pollination moves pollen. Fertilisation joins gametes | The ovule becomes a seed |
Open your NCERT book. Chapter 13 is Our Home: Earth, a Unique Life Sustaining Planet. It is the last chapter of the book.