c2

• Water is a substance composed of the chemical elements hydrogen and oxygen and existing in gaseous, liquid, and solid states
• Water is a tasteless and odourless liquid at room temperature, with the important ability to dissolve many other substances
• Thales of Miletus: 'In 16th century BCE, Thales of Miletus regarded water as the sole fundamental building block of matter'
• Thales: 'It is water that, in taking different form, constitutes the earth, atmosphere, sky, mountains, gods and men, beasts and birds, grass and trees, and animals down to worms, flies and ants. All these are different forms of water. Meditate on water!'
• 200 years later, Aristotle considered water to be one of four fundamental elements, in addition to earth, air, and fire
• Water on the Earth's surface found mainly in oceans (97.25%) and polar ice caps and glaciers (2.05%) with the balance in freshwater lakes, rivers and groundwater
• Water at high temperatures and pressures

  As water becomes hotter, the molecules seem much more likely to interact with nonpolar molecules. At 300 °C (572 °F) and high pressure, water has dissolving properties very similar to acetone (CH3COCH3), a common organic solvent
• Selected Physical properties of water

  • Molar mass – 18.0151 grams per mole
  • Melting point – 0.00 Celsius
  • Boiling point – 100.00 Celsius
  • Viscosity – 0.8903 centipoise
• Why water is necessary for life?

  Water makes up 60-75% of human body weight. A loss of 4% of the total body water leads to dehydration, and a loss of 15% can be fatal
• Water as the "Universal Solvent"


  • The cohesion of water molecules helps plants take up water at their roots. Cohesion also contributes to water's high boiling point
  • On a biological level, water's role as a solvent helps cells transport and use substances like oxygen or nutrients. Water-based solutions like blood help carry molecules to the necessary locations. Thus, water's role as a solvent facilitates the transport of molecules like oxygen for respiration and has a major impact on the ability of drugs to reach their targets in the body
  • Water supports cellular structure through phospholipid bilayers
  • Water supports photosynthesis, DNA, protein, and buffers cells from dangerous effects of acids and bases
• In conclusion, water is vital for all life. Its versatility and adaptability help perform important chemical reactions. Its simple molecular structure helps maintain important shapes for cells' inner components and outer membrane. No other molecule matches water when it comes to unique properties that support life
• Cell


  Cells are considered the basic unit of life
• Components of cells


  • Cytoplasm- molecules and organelles
  • Nucleic acids
  • Proteins
  • Carbohydrates
  • Lipids
• Nucleic Acids


  Molecules that contain and help express a cell's genetic code. DNA is the molecule that contains all of the information required to build and maintain the cell. RNA has several roles associated with expression of the information stored in DNA
• Proteins


  Made from chains of smaller molecules called amino acids and they serve a variety of function in the cell, both catalytic and structural
• Carbohydrates


  The starches and sugars in cells, are another important type of organic molecule. Simple carbohydrates are used for the cell's immediate energy demands, whereas complex carbohydrates serves as intracellular energy stores
• Lipids


  Molecules that are components of cell membranes. They are also involved in energy storage, as well as relaying signals within cells and from bloodstream to cell's interior