Numerical answer
Five sentences related to a topic are given below. Four of them can be put together to form a coherent, meaningful and unified paragraph. Identify the sentence that does not fit and enter its number.
1. Deep-sea hydrothermal vents host ecosystems that derive energy not from sunlight but from chemical reactions involving hydrogen sulphide.
2. Bacteria near these vents oxidize sulphur compounds, a process called chemosynthesis, to produce the organic matter that sustains the entire local food web.
3. Tube worms, crabs, and shrimp found at vents often host these chemosynthetic bacteria directly within their tissues.
4. Solar panels convert sunlight into electricity through the photovoltaic effect, a process unrelated to biological energy production.
5. The discovery of vent ecosystems in 1977 overturned the assumption that all life on Earth ultimately depends on photosynthesis.
1. Deep-sea hydrothermal vents host ecosystems that derive energy not from sunlight but from chemical reactions involving hydrogen sulphide.
2. Bacteria near these vents oxidize sulphur compounds, a process called chemosynthesis, to produce the organic matter that sustains the entire local food web.
3. Tube worms, crabs, and shrimp found at vents often host these chemosynthetic bacteria directly within their tissues.
4. Solar panels convert sunlight into electricity through the photovoltaic effect, a process unrelated to biological energy production.
5. The discovery of vent ecosystems in 1977 overturned the assumption that all life on Earth ultimately depends on photosynthesis.
Show answer and solution
Answer: 4
Sentences 1, 2, 3, and 5 together describe chemosynthetic, sunlight-independent ecosystems at hydrothermal vents and their scientific significance. Sentence 4 discusses solar panels and the photovoltaic effect, an engineering topic about converting sunlight to electricity, which is thematically and logically disconnected from the biological chemosynthesis narrative of the other four sentences, even though both mention energy conversion. It is the odd one out.
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