Answer: Photosynthesis in surface waters fixing CO 2 into organic matter, which sinks as particles or via organisms to depth, sequestering carbon.
- A Through large-scale physical mixing of ocean water layers by wind and currents alone, a purely physical process unrelated to photosynthetic carbon fixation by phytoplankton
- B Photosynthesis in surface waters fixing CO<sub>2</sub> into organic matter, which sinks as particles or via organisms to depth, sequestering carbon
- C Through volcanic activity releasing carbon dioxide from vents on the ocean floor, a geological carbon source rather than the biologically driven sequestration process
- D Through the long-distance seasonal migration patterns of whales across ocean basins, a description of animal migration unrelated to sinking organic particulate carbon
Correct answer: B. Photosynthesis in surface waters fixing CO<sub>2</sub> into organic matter, which sinks as particles or via organisms to depth, sequestering carbon
Explanation: Biological pump: phytoplankton fix CO<sub>2</sub> (primary production). Organic matter sinks as marine snow or via food web to deep ocean. Deep respiration/decomposition releases CO<sub>2</sub> in deep water, preventing it from re-entering atmosphere.
Energy pyramid showing a simple food chain (producer to herbivore to carnivore) with energy decreasing roughly tenfold at each trophic level.
Concept context
Ecosystems, food chains, energy flow, nutrient cycles, biodiversity, and conservation.