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  3. When marine organisms called phytoplankton photosynthesize, they absorb carbon dioxide dissolved in seawater, potentially causin

When marine organisms called phytoplankton photosynthesize, they absorb carbon dioxide dissolved in seawater, potentially causin

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问题 When marine organisms called phytoplankton photosynthesize, they absorb carbon dioxide dissolved in seawater, potentially causing a reduction in the concentration of atmospheric carbon dioxide, a gas that contributes to global warming. However, phy-
line toplankton flourish only in surface waters where iron levels are sufficiently high. Mar-
5 tin therefore hypothesized that adding iron to iron-poor regions of the ocean could help alleviate global warming. While experiments subsequently confirmed that such a procedure increases phytoplankton growth, field tests have shown that such growth does not significantly lower atmospheric carbon dioxide. When phytoplankton utilize carbon dioxide for photosynthesis, the carbon becomes a building block for organic
10 matter, but the carbon leaks back into the atmosphere when predators consume the phytoplankton and respire carbon dioxide.
It can be inferred from the passage that Martins hypothesis includes which of the following elements?
选项 A、A correct understanding of how phytoplankton photosynthesis utilizes carbon dioxide
B、A correct prediction about how the addition of iron to iron-poor waters would affect phytoplankton growth
C、An incorrect prediction about how phytoplankton growth would affect the concentration of atmospheric carbon dioxide
答案A，B，C
解析 All three choices are correct. Martin’s hypothesis was that adding iron to iron-poor regions of the ocean could help alleviate global warming.
Choice A is correct: the passage presents Martin as using the standard understanding of how phytoplankton photosynthesize as a basis for the hypothesis.
Choice B is correct: the passage states that experiments confirmed that adding iron to iron-poor regions increases phytoplankton growth in those regions. Therefore, Martin’s prediction about this was correct.
Choice C is correct: it can be inferred that in Martin’s hypothesis the means by which adding iron in certain regions could alleviate global warming is that phytoplankton increase in those regions and absorb atmospheric carbon dioxide. The passage states that predators who consume phytoplankton respire carbon dioxide, so that the carbon dioxide absorbed by phytoplankton reenters the atmosphere. Therefore, Martin’s prediction about this was incorrect.
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