The Water Cycle

Key Idea

• Water is an abiotic factor (non-living) that cycles through ecosystems.

• Most water on Earth is in the oceans (salt water).

Main Stages of the Cycle

1. Evaporation

• Sun’s energy heats seas/oceans.

• Water evaporates into the air as water vapour.

2. Condensation

• Water vapour cools in the atmosphere.

• Condenses into clouds.

3. Precipitation

• Water falls back to the ground as rain, snow, hail, or sleet.

• All precipitation is fresh water (no salt).

4. Return to Oceans

• Some water:

  • Evaporates again.

  • Passes through rocks → forms aquifers.

  • Forms rivers/streams → flow back into the sea.

Role of Living Organisms

• Plants:

  • Absorb water through roots.

  • Water travels in xylem.

  • Lost from leaves via stomata → transpiration.

• Animals:

  • Take in water through food and drink.

  • Release water in urine, faeces, and exhalation.

✅ Key Points / Summary

• The water cycle involves evaporation → condensation → precipitation → return to oceans.

• Precipitation is always fresh water.

• Plants contribute by transpiration, animals by excretion and breathing.