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Topic 5: Ecology and evolution

Topic 5: Ecology and evolution. 5.1 Communities and ecosystems. Autotrophs vs hetertrophs. What do these words mean? Give examples of organisms from each group. detritivores. Ingests and then digest dead organic matter Eg . Earthworms, woodlouse. saprotroph.

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Topic 5: Ecology and evolution

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  1. Topic 5: Ecology and evolution 5.1 Communities and ecosystems

  2. Autotrophsvshetertrophs • What do these words mean? • Give examples of organisms from each group.

  3. detritivores • Ingests and then digest dead organic matter • Eg. Earthworms, woodlouse

  4. saprotroph • An organism that lives in or on non-living organic matter • They secrete digestive enzymes into it and absorb the products of digestion • Digest first, then absorb • Nature’s recylers – recycle nutrients • Heterotrophs • Eg. Fungi, bacteria

  5. consumer • An organism that ingests other organic matter that is living or recently killed • Heterotrophs

  6. Food chains • Show the flow of energy through the trophic levels of a feeding relationship • Trophic level: feeding position of an organism in food chain • Each organism feeds on the organism before it • Arrows point towards the consumer • Indicate the direction of energy and nutrient flow

  7. What is wrong with this?

  8. challenge • Group A: Create a food chain with three linkages (four organisms) from a desert ecosystem • Group B: Create a food chain with three linkages (four organisms) from a grassland ecosystem • Draw on the whiteboard. Now lets label it together as a class.

  9. Food chain examples Tertiary consumers Secondary consumers Primary consumers Producers

  10. challenge • Can you pick out a 3 step food chain and a 4 step food chain? • Can you find two organisms that fit into more than one trophic level?

  11. Food web • Shows complex feeding relationships showing interacting food chains

  12. Challenge answers

  13. Energy • Light is the initial source of energy for almost all communities • This comes from the SUN

  14. Energy flow • Energy flows through food chains, but some (90%) is lost between each trophic level • Loss is due to: • Material not consumed • Material not assimilated • Heat loss through cellular respiration Nutrients are recycled

  15. Energy pyramids • Show the flow of energy between trophic levels • Never 100% efficient, around 90% loss • The width of the bars is proportional to the energy in that tropic level Only approx. 10% of energy is passed on to the next trophic level. Unit = kJ m-2 y-1

  16. homework • DBQ pg. 169 • Working with data pg. 170

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