Numerical answer
Directions: Five sentences are given below, labelled 1, 2, 3, 4 and 5. Four of them, when arranged in proper order, form a coherent paragraph. One sentence does not belong. Identify the number of that sentence.
1. Coral reefs, though they occupy less than one percent of the ocean floor, are home to roughly a quarter of all known marine species, making them among the most biodiverse ecosystems on the planet.
2. This biodiversity depends on a delicate symbiosis between coral polyps and the microscopic algae living within their tissues, which supply the coral with most of its energy through photosynthesis.
3. Rising ocean temperatures cause corals to expel these algae in a stress response known as bleaching, which, if prolonged, can lead to the coral's death and the collapse of the reef ecosystem it supports.
4. Freshwater lakes, by contrast, support a comparatively narrow range of species because they lack the stable temperature gradients found in tropical marine environments.
5. Reef restoration projects have begun experimenting with coral strains bred to tolerate higher temperatures, in the hope of slowing this collapse.
1. Coral reefs, though they occupy less than one percent of the ocean floor, are home to roughly a quarter of all known marine species, making them among the most biodiverse ecosystems on the planet.
2. This biodiversity depends on a delicate symbiosis between coral polyps and the microscopic algae living within their tissues, which supply the coral with most of its energy through photosynthesis.
3. Rising ocean temperatures cause corals to expel these algae in a stress response known as bleaching, which, if prolonged, can lead to the coral's death and the collapse of the reef ecosystem it supports.
4. Freshwater lakes, by contrast, support a comparatively narrow range of species because they lack the stable temperature gradients found in tropical marine environments.
5. Reef restoration projects have begun experimenting with coral strains bred to tolerate higher temperatures, in the hope of slowing this collapse.
Show answer and solution
Answer: 4
Sentences 1, 2, 3 and 5 form a coherent chain about coral reef biodiversity, the algal symbiosis it depends on, the threat of bleaching, and restoration efforts to counter it. Sentence 4, about freshwater lakes, introduces an unrelated comparison that does not fit this focused progression on coral reefs, making it the odd one out.
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