Science Chapter 2

• Ecosystem


  All the living organisms that share a region and interact with each other and their non-living environment
• Ecosystem


  • Composed of both living (biotic) and non-living (abiotic) components
  • Biotic factors are living things, their remains, and features associated with their activities
  • Abiotic factors are the non-living physical and chemical components
• Ecosystems


  • Coral reef
  • Beaver pond
  • Rotting log
• Biotic factors


  Living things, their remains, and features associated with their activities
• Abiotic factors


  Non-living physical and chemical components of an ecosystem
• Population


  All the individuals of a single species in a particular area
• Community


  Individuals from all of the populations in an ecosystem
• An ecosystem is the community and its interactions with the abiotic environment
• Ecosystems can differ dramatically in size and in their biotic and abiotic features
• Large ecosystems may include many much smaller ecosystems
• Sustainable ecosystem


  An ecosystem that is maintained through natural processes
• Human activities often change the biotic and abiotic features of an ecosystem, which can render a previously sustainable ecosystem unsustainable
• Radiant energy


  Energy that travels through empty space
• Light energy


  Visible forms of radiant energy
• Thermal energy


  The form of energy transferred during heating or cooling
• Photosynthesis


  The process in which the Sun's energy is converted into chemical energy
• Producer


  An organism that makes its own energy-rich food compounds using the Sun's energy
• About 70% of the radiant energy is absorbed by the hydrosphere and lithosphere and converted into thermal energy
• The remaining 30% of the radiant energy is reflected directly back into space
• A mere 0.023% of the radiant energy is absorbed directly by living organisms in a process called photosynthesis
• Thermal energy keeps Earth's surface warm, but it cannot provide organisms with the energy they need to grow and function
• Light energy can be used by some organisms, but it cannot be stored and is not available during the night
• Chemical energy can be stored in cells and then released when needed
• Chemical energy is used by all organisms to perform functions, including movement, growth, and reproduction
• As chemical energy is used, it must be replaced
• Photosynthesis


  Carbon dioxide + water + light energy -> sugar + oxygen
• Virtually all of the chemical energy contained in food was once light energy captured in the process of photosynthesis
• Most producers use light energy to convert two low-energy chemical compounds (carbon dioxide and water) into high-energy compounds (sugars)
• In the process of photosynthesis, oxygen gas is released into the environment as a by-product
• The sugar formed in photosynthesis contains stored chemical energy
• Most plants convert the sugar to starch for storage
• Some sugars produced through photosynthesis are used as building materials
• The carbon, hydrogen, and oxygen in the carbon dioxide and water are rearranged to form sugars and oxygen gas during photosynthesis
• The components in the sugars are then rearranged to form different combinations, such as carbohydrates or proteins
• Cellular respiration


  The process by which sugar and oxygen are converted into carbon dioxide and water, to provide energy for the cell
• Indian pipe


  Plant that does not photosynthesize, instead obtains energy-rich food directly from fungi in the soil
• Indian pipe


  • Has small, functionless leaves
  • No need for green chlorophyll
• Some Ontario plants, including Indian pipe, do not photosynthesize
• Cellular respiration


  Process by which sugar and oxygen are converted into carbon dioxide and water, to provide energy for the cell
• Photosynthesis produces stored energy in the form of sugar

  To make stored energy available for use, the plant performs the complementary reaction called cellular respiration