Ecosystem processes — A/L Biology

How do I practise Ecosystem processes?

1 question with a worked solution

1. Which of the following ecological pyramids can NEVER be inverted in an undisturbed natural ecosystem, governed by the Second Law of Thermodynamics?
   1. A) Pyramid of energy
   2. B) Pyramid of biomass
   3. C) Pyramid of numbers
   4. D) Pyramid of standing crop
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   Correct answer: A) Pyramid of energy

   Energy transfer between successive trophic levels is inefficient due to respiratory heat loss and metabolic work (~10% trophic efficiency). Because energy is constantly dissipated and cannot be recycled, productivity at higher trophic levels is always lower than at preceding levels, making pyramids of energy strictly upright.

   Show worked solution

   Step 1: Check pyramid inversion possibilities: - Numbers: inverted in parasite food chains or single tree ecosystems. - Biomass: inverted in marine ecosystems (phytoplankton turnover fast, zooplankton biomass higher). - Energy: strictly upright, obeys thermodynamic dissipation. Answer: Pyramid of energy.
   Modelled on: the A/L Biology examination pattern

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Where does Ecosystem processes fit in the syllabus?

Year 2 · Term 2