Module 3

• Almost every process important to life (living systems) depends on a steady flow of energy
• Energy


  The ability to do work
• Forms of energy

  • Mechanical energy (kinetic energy)
  • Radiant energy (sun)
  • Sound energy
  • Chemical energy
  • Heat energy
  • Electrical energy
  • Nuclear Energy
• Kinetic energy

  Energy of motion
• Potential energy

  Stored energy
• Energy sources

  • Renewable
  • Non-renewable
• Non-renewable resources supply the bulk of our energy needs because of technologies that allow them to be harnessed on a large scale to meet consumer needs
• Autotrophs


  Primary producers that harness radiant energy and convert it to chemical energy
• Heterotrophs


  Organisms that cannot capture light or chemical energy to make food and thus, mainly rely on autotrophs
• Chemoautotrophs


  Organisms that create their own organic food from inorganic chemicals
• Trophic level


  A feeding level, often represented in a food chain or food web

  
• Trophic levels

  • Primary producers
  • Primary consumers (herbivores)
  • Secondary consumers
  • Tertiary consumers
• Only about 10% of net energy production at one trophic level is passed on to the next level
• Decomposers process large amounts of organic material and return nutrients to the ecosystem in inorganic form, which are then taken up again by primary producers
• Ecological pyramids


  Graphical representations designed to show relationships between energy and trophic levels in an ecosystem

  
• Types of ecological pyramids

  • Pyramid of biomass
  • Pyramid of energy
  • Pyramid of numbers
• As the trophic level increases in a food chain, the amount of toxic build up also increases
• Toxins like DDT become stored in organism's tissues
• Ecological Pyramid


  • Shows relationship between energy and trophic level

  
• DDT or Dichlorodiphenyltrichloroethane was a contact poison used to control the spread of insect-borne diseases like malaria and typhus
• The use of this insecticide was banned after studies have shown that as the trophic level increases in a food chain, the amount of toxic build up also increases
• Toxins like DDT become stored in organism's tissues and fat
• Predators accumulate higher toxins than the prey because predators eat more
• Biological magnification


  Increasing concentration of persistent, toxic substances at each trophic level, from the primary producers to the different consumer levels
• Energy flows in one direction through ecosystems, entering as sunlight (or inorganic molecules for chemoautotrophs) and leaving as heat during the many transfers between trophic levels
• Matter that makes up living organisms is conserved and recycled
• Cycle


  A continual process of transformations where the basic components are used over and over again in slightly different forms, but always return to the original form to begin the cycle again
• Earth is a closed system for matter, thus, all elements needed for living systems came from what was present in the Earth's crust so many billion years ago
• Matter is continually recycled on time scales which can vary from a few days to millions of years
• Biogeochemical cycle


  The recycling of inorganic matter between living organisms and their environment, involving geological and chemical processes
• Functions of biogeochemical cycles


  • Enable transformation of matter from one form to another
  • Enable transfer of molecules from one locality to another
  • Facilitate storage of elements
  • Assist in functioning of ecosystems
  • Link living organisms with living organisms and living organisms with abiotic factors
  • Regulate the flow of substances
• Key elements in organic molecules

  • Hydrogen
  • Oxygen
  • Carbon
  • Nitrogen
  • Phosphorus
• Water Cycle


  1. Evaporation

  2. Transpiration

  3. Precipitation

  4. Surface runoff

  5. Groundwater flow

  
• Freshwater


  Only 0.3% of Earth's water is found in surface water of lakes, rivers, and swamps
• Living things need water to live, as our body is mostly water
• Carbon Cycle


  1. Photosynthesis

  2. Respiration

  3. Combustion

  4. Decomposition
• Importance of carbon

  18% of our body is made up of carbon atoms, essential for cell plasma membranes, sugar molecules for fuel, and DNA
• Nitrogen Cycle


  1. Nitrogen fixation

  2. Nitrification

  3. Denitrification

  4. Ammonification

  
• Importance of nitrogen


  Key component in living organisms found in DNA and proteins, essential for plant growth and agriculture

  
• Phosphorus Cycle


  1. Weathering

  2. Runoff

  3. Uptake by organisms

  4. Decomposition