Numerical answer
The four sentences below, when properly sequenced, form a coherent paragraph. Arrange them in the correct order.
1. Yet the very features that make coral reefs biologically rich also make them acutely vulnerable to small shifts in ocean temperature and chemistry.
2. Coral reefs occupy less than one percent of the ocean floor but support roughly a quarter of all known marine species, an outsized concentration of biodiversity relative to their physical footprint.
3. This vulnerability means that reefs often function as early indicators of broader oceanic stress well before such stress becomes apparent elsewhere in the marine ecosystem.
4. Bleaching events, in which corals expel the symbiotic algae that supply both their colour and much of their energy, can be triggered by temperature deviations of only one or two degrees sustained for several weeks.
1. Yet the very features that make coral reefs biologically rich also make them acutely vulnerable to small shifts in ocean temperature and chemistry.
2. Coral reefs occupy less than one percent of the ocean floor but support roughly a quarter of all known marine species, an outsized concentration of biodiversity relative to their physical footprint.
3. This vulnerability means that reefs often function as early indicators of broader oceanic stress well before such stress becomes apparent elsewhere in the marine ecosystem.
4. Bleaching events, in which corals expel the symbiotic algae that supply both their colour and much of their energy, can be triggered by temperature deviations of only one or two degrees sustained for several weeks.
Show answer and solution
Answer: 2143
Sentence 2 introduces the topic (reefs' outsized biodiversity). Sentence 1 pivots with 'yet' to their vulnerability, which sentence 4 then explains concretely (bleaching mechanism). Sentence 3 draws the broader conclusion ('this vulnerability means...') that closes the paragraph, referring back to sentence 1's point. Order: 2-1-4-3.
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