Energy and Matter Exchange in the Biosphere

How energy flows one way through the biosphere while matter cycles round it.

12 questions, free, marked as you go with a worked explanation on every one.

What this covers

The questions

  1. What is the ultimate source of energy for almost all ecosystems on Earth?
  2. Producers in an ecosystem capture 10 000 kJ of energy. Using the usual 10% rule, how much energy reaches the secondary consumers?
  3. Why does an energy pyramid get narrower towards the top?
  4. Which of these cycle through the biosphere and are reused? Select all that apply.
  5. What role do decomposers play in the biosphere?
  6. Which statement about the greenhouse effect is correct?
  7. Which of these is an abiotic factor in an ecosystem?
  8. In the carbon cycle, which process removes carbon dioxide from the atmosphere?
  9. In a food chain, a producer captures 5000 kJ of energy. Following the 10 percent rule, how much energy is available to the primary consumer, in kilojoules?
  10. In a food web, an organism that eats both plants and animals is called a:
  11. What role do decomposers play in a food web?
  12. A food web shows three trophic levels above the producers. If the producers capture 8000 kJ, and the 10 percent rule applies at every transfer, how much energy reaches the third consumer level, in kilojoules?

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