Numerical answer
Five sentences numbered 1–5 are given below. Four of them form a coherent paragraph, while one does not fit. Key in the number of the sentence that does NOT fit.
1. Migratory birds rely on an internal magnetic compass to navigate distances that can span entire continents.
2. Researchers have found that a protein called cryptochrome, located in the retina, may allow birds to literally see the Earth's magnetic field as a pattern of light and shadow overlaid on their normal vision.
3. This sensitivity is thought to be disrupted by artificial radio-frequency noise, which several field experiments have shown causes birds to lose their oriented bearings when exposed to it.
4. Bird populations worldwide have declined by nearly 30% since 1970, largely due to habitat loss and pesticide use.
5. Because the mechanism depends on quantum effects within the protein at a molecular scale, some scientists describe it as one of the few confirmed instances of quantum biology operating in a living organism.
1. Migratory birds rely on an internal magnetic compass to navigate distances that can span entire continents.
2. Researchers have found that a protein called cryptochrome, located in the retina, may allow birds to literally see the Earth's magnetic field as a pattern of light and shadow overlaid on their normal vision.
3. This sensitivity is thought to be disrupted by artificial radio-frequency noise, which several field experiments have shown causes birds to lose their oriented bearings when exposed to it.
4. Bird populations worldwide have declined by nearly 30% since 1970, largely due to habitat loss and pesticide use.
5. Because the mechanism depends on quantum effects within the protein at a molecular scale, some scientists describe it as one of the few confirmed instances of quantum biology operating in a living organism.
Show answer and solution
Answer: 4
Sentences 1, 2, 3 and 5 all build a single coherent account of how birds use a magnetic-field-sensing protein to navigate. Sentence 4, about population decline due to habitat loss and pesticides, is an unrelated statistic about a different cause (human impact on bird numbers) and breaks the paragraph's focus on the navigation mechanism.
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