general

• Biodiversity


  The variety of life found in a place on Earth or, often, the total variety of life on Earth
• Species richness


  A common measure of biodiversity, the count of species in an area
• Species richness


  • Colombia and Kenya have more than 1,000 breeding species of birds
  • Forests of Great Britain and eastern North America have fewer than 200 species
  • A coral reef off northern Australia may have 500 species of fish
  • The rocky shoreline of Japan may be home to only 100 species
• Biodiversity encompasses the genetic variety within each species and the variety of ecosystems that species create
• Measuring biodiversity


  Examining counts of species is perhaps the most common method used to compare the biodiversity of various places
• Some species are deemed more valuable or more interesting than others when measuring biodiversity
• Taxonomic diversity


  Examining the diversity that exists above the species level, in the genera, families, orders, classes, and phyla to which species belong
• There are fewer animal phyla in terrestrial environments than in the oceans
• Taxonomically distinct species


  Species that are the only one in their genus or family, which may be a valuable source for medicines
• Species in large genera

  May possess something of the evolutionary vitality that has led their genus to be so diverse
• Extreme environments with few but distinctive species


  • Summits of active Antarctic volcanoes
  • Hot springs (e.g. Yellowstone National Park)
  • Deep-sea hydrothermal vents
• The bacterium Thermus aquaticus, found in Yellowstone hot springs, was the source of Taq polymerase, a crucial enzyme for DNA amplification
• Endemic species


  Species having relatively small ranges, found only in a particular area
• Endemic species are much more vulnerable to human activity than are more widely distributed species
• Genetic diversity within species


  Differences in characteristics like height, weight, skin/eye colour, behaviour, disease resistance
• Ecological community diversity


  The range of ecological communities (e.g. forests, prairies) that an area may contain
• An area with both forests and prairies is more diverse than one with forests alone, as each assemblage is expected to house different species
• Ecological assemblages


  Defined in a variety of ways, including association, habitat, ecosystem, biome, life zone, ecoregion, landscape, or biotype
• There is no agreement on the boundaries of ecological assemblages
• The catalog of Earth's biodiversity is very incomplete, with only about 1.9 million species having scientific names out of an estimated 10 million total species
• The pace of species population declines and extinctions has risen dramatically over the last century due to climate change and human activities
• Biodiversity hotspots


  Biologically rich but threatened regions containing high numbers of endemic species, identified to assist in conservation priorities
• The United Nations named 2010 as the International Year of Biodiversity to raise public awareness about the importance of biodiversity and reinforce conservation efforts
• Substances can exist in three states of matter - solid, liquid and gas
• All substances are made from particles, and the forces between the particles are different in solids, liquids and gases
• The arrangement, movement and spacing of the particles explain many of the properties of solids, liquids and gases
• Solids


  • Particles are closely packed in a regular arrangement, held in fixed positions by strong forces, can only vibrate
  • Have a fixed shape and cannot flow
• Liquids


  • Particles are closely packed but randomly arranged, held by weaker forces, can move from place to place
  • Do not have a fixed shape and can flow
• Gases


  • Particles are widely spaced, have enough energy to overcome attractive forces, move quickly in random directions
  • Do not have a fixed shape or volume, can expand to fill their container, can be compressed
• Solids and liquids cannot be easily compressed, but gases can