The distribution of water on the Earth’s surface is extremely uneven. Only 3% of water on the surface is fresh; the remaining 97% resides in the ocean. Of freshwater, 69% resides in glaciers, 30% underground, and less than 1% is located in lakes, rivers and swamps. Looked at another way, only one percent of the water on the Earth’s surface is usable by humans, and 99% of the usable quantity is situated underground.
Chapter 1 - Nutrition in Plants
Chapter 2 - Nutrition in Animals
Chapter 5 - Acids, Bases and Salts
Chapter 6 - Physical and Chemical Changes
Chapter 7 - Weather, Climate and Adaptations of Animals to Climate
Chapter 8 - Winds, Storms and Cyclones
Chapter 10 - Respiration in Organisms
Chapter 11 - Transportation in Animals and Plants
Chapter 12 - Reproduction in Plants
Chapter 14 - Electric Current and Its Effects
Chapter 16 - Water: A Precious Resource
Chapter 17 - Forests: Our Lifeline