Numerical answer
Five sentences related to a common theme are given below, labelled 1 to 5. Four of them, when arranged in a specific order, form a coherent paragraph. Identify the sentence that does not fit and key in its number.
1. Coral reefs occupy less than one percent of the ocean floor yet support roughly a quarter of all known marine species.
2. This density arises from the physical complexity of reef structures, which create countless microhabitats for organisms of vastly different sizes and needs.
3. Rising ocean temperatures have caused repeated mass bleaching events, in which corals expel the algae that give them both colour and nutrients.
4. The symbiotic algae living within coral tissue also convert sunlight into food, sustaining the coral animal itself in nutrient-poor tropical waters.
5. Reef fish, in turn, rely on this structural and nutritional abundance for shelter, breeding grounds and food.
1. Coral reefs occupy less than one percent of the ocean floor yet support roughly a quarter of all known marine species.
2. This density arises from the physical complexity of reef structures, which create countless microhabitats for organisms of vastly different sizes and needs.
3. Rising ocean temperatures have caused repeated mass bleaching events, in which corals expel the algae that give them both colour and nutrients.
4. The symbiotic algae living within coral tissue also convert sunlight into food, sustaining the coral animal itself in nutrient-poor tropical waters.
5. Reef fish, in turn, rely on this structural and nutritional abundance for shelter, breeding grounds and food.
Show answer and solution
Answer: 3
Sentences 1, 2, 4 and 5 together build a coherent account of why coral reefs support such rich biodiversity: the reef's physical complexity (2) and the algae's nutritional role (4) explain the high species density stated in (1), and (5) extends this to reef fish. Sentence 3, about bleaching from rising temperatures, introduces an unrelated topic (a threat to reefs) rather than continuing the explanation of biodiversity, making it the odd one out.
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