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. Octopuses possess three hearts, two that pump blood through the gills and one that circulates it to the rest of the body.
2. Their blood is blue rather than red because it uses copper-based hemocyanin instead of iron-based hemoglobin to transport oxygen.
3. This copper-based system works more efficiently than hemoglobin in the cold, low-oxygen conditions of deep or cold ocean water.
4. Octopuses are also remarkably intelligent, capable of solving puzzles, using tools and escaping enclosures thought to be secure.
5. The central heart pauses when the octopus swims, which is one reason octopuses tend to prefer crawling over swimming.
1. Octopuses possess three hearts, two that pump blood through the gills and one that circulates it to the rest of the body.
2. Their blood is blue rather than red because it uses copper-based hemocyanin instead of iron-based hemoglobin to transport oxygen.
3. This copper-based system works more efficiently than hemoglobin in the cold, low-oxygen conditions of deep or cold ocean water.
4. Octopuses are also remarkably intelligent, capable of solving puzzles, using tools and escaping enclosures thought to be secure.
5. The central heart pauses when the octopus swims, which is one reason octopuses tend to prefer crawling over swimming.
Show answer and solution
Answer: 4
Sentences 1, 2, 3 and 5 form a coherent thread about octopus circulatory biology: heart structure (1), blood chemistry (2), its advantage in cold water (3), and a behavioural consequence of heart function (5). Sentence 4, about octopus intelligence and tool use, is unrelated to this circulatory-system thread, making it the odd one out.
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