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2013-10-07 16:05:56
biology gcse

OCR B2 revision gateway
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  1. What is the artificial classification system?
    It's based on one or two characteristics that make identification easier, e.g birds that always live near the sea are called seabirds.
  2. What is a species?
    A group of organisms that can interbreed to produce fertile offspring
  3. What is some energy at each trophic level transferred to?
    Less useful forms such as heat from respiration, egestion and excretion
  4. What is a trophic level?
    A level of a food chain
  5. What do decomposers do?
    Convert proteins and Urea into ammonia
  6. What do Nitrifying bacteria do?
    They convert ammonia to nitrates
  7. What do denitryfying bacteria do?
    Convert nitrates to nitrogen gas
  8. Where are Nitrogen fixing bacteria found?
    In the root nodules
  9. Why is a growth in population happening?
    The birth rate is exceeding death rate
  10. What does the recycling of carbon involve?
    • Photosynthesis
    • Feeding
    • Respiration
    • Decomposition
  11. Why are food chains limited to about four levels?
    The energy would run out if the food chain lasted longer
  12. How can you work out the efficiency of energy transfer between trophic levels?
    Energy used for growth / energy input
  13. What is a generalist?
    A animal that can live in a number of habitats