Water — The Essence of Life

Forms and Sources of Water

• Water exists in three forms: liquid (rain, rivers, lakes), solid (ice, snow), and vapour (steam, clouds).
• Although Earth’s surface is mostly water, only a very small fraction is freshwater, the rest is saline.
• Freshwater comes from sources like rivers, lakes, ponds, glaciers, and groundwater.
• All living beings depend on freshwater for drinking, farming, and daily activities.

The Water Cycle

• The Sun’s heat causes evaporation, changing water into vapour.
• Water vapour condenses into clouds, which eventually fall as rain, snow, or hail.
• Precipitated water returns to rivers, lakes, and oceans, completing the cycle.
• The cycle shows the continuous circular movement of water on Earth.

Groundwater and Surface Water

• Rainwater seeps through soil and rocks to form groundwater, which is drawn from wells and pumps.
• Groundwater recharge happens best in open, green areas, ponds, and soak pits, but is blocked by concrete surfaces.
• Surface water includes rivers, lakes, ponds, and wetlands.
• Water flow follows landforms (mountains, valleys) and can even shape them over time.

Life in Water (Aquatic Plants & Animals)

• Freshwater habitats support fish, frogs, turtles, insects, snakes, and water birds.
• Aquatic plants include floating (lotus, water lily), submerged, and free-floating (water hyacinth) species.
• Animals and plants in water have special adaptations like fins, gills, floating leaves, and waxy coatings.
• Freshwater ecosystems have food chains (e.g., fish → frog → bird → human), showing interdependence.

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