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## Learn Water has unique properties that support life. Water can dissolve many chemicals and exist in all three states of matter - solid, liquid, and gaseous states - within the range of known temperatures on the Earth's surface. Water is essential to the continuation of life on Earth. All living c...

## Learn Water has unique properties that support life. Water can dissolve many chemicals and exist in all three states of matter - solid, liquid, and gaseous states - within the range of known temperatures on the Earth's surface. Water is essential to the continuation of life on Earth. All living cells have a membrane that separates the organism from its environment. Water passes from the environment to the inside of the living cell through this membrane, carrying the substances needed to produce energy as well as eliminating waste products to the outside. ### The hydrosphere on Earth: - The hydrosphere distinguishes Earth from other planets in the solar system. - About 70% of the Earth's surface is covered by water. - About 97% of this water is found in the oceans, seas, and salt lakes as salt water. - The fresh water is found in rivers, freshwater lakes and groundwater represents approximately 1%. - The remainder part represents the frozen water in polar regions, mountain peaks and glaciers. **Egypt is characterized by its diverse aquatic environments:** - The Nile River - The Gulf of Suez - The Gulf of Aqaba, - The Red Sea - The Mediterranean Sea, - Many salt and freshwater lakes. ### Research activity Using various sources, research about: 1. What are the different tools that measure annual rainfall that falls on a particular place? 2. Can scientists predict future changes in rainfall patterns?