B) How It Works


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B) How It Works

  1. 1. Topic: The Biosphere Sub-topic b: How it Works
  2. 2. Individual Individuals Individual Population Community
  3. 3. Producers and Consumers <ul><li>All organisms in an ecosystem need food to survive. </li></ul><ul><li>How an organism obtains food can be divided into two groups: </li></ul><ul><ul><li>Producers </li></ul></ul><ul><ul><li>Consumers </li></ul></ul>
  4. 4. Producers <ul><li>All green plants produce their own food. </li></ul><ul><li>They use the sunlight's energy to synthesise food… PHOTOSYNTHESIS </li></ul><ul><li>This means that the sun is the source off all energy in a food chain. </li></ul>
  5. 5. Consumers <ul><li>Organisms that eat other organisms are consumers. </li></ul><ul><ul><li>Herbivores </li></ul></ul><ul><ul><ul><li>Consume plant material </li></ul></ul></ul><ul><ul><li>Carnivores </li></ul></ul><ul><ul><ul><li>Consume animal material </li></ul></ul></ul><ul><ul><li>Omnivores </li></ul></ul><ul><ul><ul><li>Consume plant and animal material </li></ul></ul></ul>
  6. 6. Food Chains <ul><li>Energy is transferred in the form of chemical energy in food from plants to animals and then to other animals. </li></ul><ul><li>A producer can be eaten by a herbivore – primary consumer. </li></ul><ul><li>A herbivore can in turn be eaten by an animal – secondary consumer. </li></ul>
  7. 7. Green Plant ( producer ) Rabbit ( primary consumer ) Fox ( secondary consumer ) <ul><li>The feeding relationship is called a food chain , and is written as </li></ul><ul><li>Green Plant  Rabbit  Fox </li></ul><ul><li>The arrows in a food chain point from the food to the feeder and show the direction of energy flow. </li></ul>
  8. 8. Food Webs <ul><li>A feeding relationship shown by a food chain is never so simple in nature. </li></ul><ul><li>Food chains interconnect at many points. </li></ul><ul><li>Organisms within a food chain are not isolated from each other, but may link and be part of other food chains. </li></ul><ul><li>This interconnection of food chains is called a food web. </li></ul>
  9. 9. Fox Weasel Hedgehog Frog Snail Vole Rabbit Oak Primrose plant Owl
  10. 10. Energy Loss <ul><li>Every time an organism eats another, energy is transferred from the food to the feeder: </li></ul><ul><li>Oak leaf  Caterpillar  Shrew  Badger </li></ul><ul><li>Not all of the energy available at each step of the food chain is passed onto the next step. </li></ul><ul><li>Energy is lost. </li></ul>
  11. 11. Caterpillar eats the leaf Energy not used Some of the energy in the leaf passes out of the caterpillar in undigested food Energy used Energy used The caterpillar uses some energy it gets from the leaf to move, feed and produce heat. This energy is lost to other animals in the food chain Energy stored The rest of the energy the caterpillar gets from the leaf is stored in the body of the caterpillar. Only the stored energy is available to the next animal in the food chain
  12. 12. Tadpole Caddis fly larvae Pond weed Water flea Algae Perch Pike Water beetle Stickleback Freshwater snail
  13. 13. What happens …and why… <ul><li>To the number of sticklebacks if all the pike are fished out of the pond </li></ul><ul><li>To the pond weed if all the snails die </li></ul><ul><li>To the number of water fleas and sticklebacks if the water beetles die of a disease </li></ul><ul><li>If the algae does not grow due to pollution </li></ul>
  14. 14. Competition is the struggle between members of a community for the same limited resources . Animals Plants Food Water Shelter Nesting Spaces Mates Nutrients Water Light (Root/leaf space)
  15. 15. Paramecium species
  16. 16. Variety A Variety A in competition with variety B
  17. 17. Variety B Variety B in competition with variety A
  18. 18. Pyramid of Numbers The diagram indicates the numbers of organisms required to support the next step in the food chain.
  19. 19. Pyramid of Numbers <ul><li>As you move up this food chain the size of the organism at each link _______ and the numbers of them _________ </li></ul><ul><li>This can be presented by a pyramid of numbers e.g. </li></ul>Pike = 10 Perch = 40 Snail = 80 Algae = 100
  20. 20. <ul><li>The graph is an irregular shape as one oak tree can provide many hundreds of greenfly with a source of energy contained in food. </li></ul>Blackbird = 10 Lady bird = 50 Greenfly = 500 Oak tree = 1 But…
  21. 21. Pyramid of Biomass <ul><li>A more accurate idea of the quantity of animal and plant material at each level of the food chain is obtained by recording the mass of the living organisms – Biomass. </li></ul><ul><li>This information can be used to construct a pyramid of biomass. </li></ul>Oak tree Greenfly Lady Bird
  22. 22. <ul><li>All pyramids of biomass have the following structure: </li></ul><ul><li>They must have this structure as the energy in the previous level of the food chain must be able to provide energy for growth, heat, movement etc. for the next level. </li></ul>Producer Primary consumer Secondary consumer
  23. 23. The Nitrogen Cycle
  24. 24. Nitrogen gas in air Mmm Waste ! Decomposition by bacteria and fungus Denitrification by bacteria Nitrogen in plants (Protein) Nitrogen fixation by bacteria Absorption by roots Nitrogen fixation by bacteria Further nitrification by bacteria Nitrogen in NITR ATES in soil Nitrogen in animals (Protein) Nitrogen in dead plant/animal bodies and waste Nitrogen in NITR I TES in soil Nitrification by bacteria Ooh, Ammonia! Nitrogen in ammonium compounds in soil