Professor: A marine biologist argues that transmission of sea lice from farm salmon to wild salmon is unlikely in the...
GMAT Critical Reasoning : (CR) Questions
Professor: A marine biologist argues that transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia, citing numerous studies suggesting that salinities less than 30 parts per thousand are unfavorable to sea-lice survival. The biologist concludes that the archipelago's 25–30 parts per thousand salinity range between March and June, the critical period for wild salmon migration, tends to suppress sea-lice proliferation. But a review of the literature shows that salinities of 25–30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice.
In this passage, the professor attempts to undermine the biologist's argument by
Passage Analysis:
| Text from Passage | Analysis |
| A marine biologist argues that transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia, citing numerous studies suggesting that salinities less than 30 parts per thousand are unfavorable to sea-lice survival. |
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| The biologist concludes that the archipelago's 25–30 parts per thousand salinity range between March and June, the critical period for wild salmon migration, tends to suppress sea-lice proliferation. |
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| But a review of the literature shows that salinities of 25–30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice. |
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Argument Flow:
The professor first presents the marine biologist's argument that relies on salinity data alone, then shows the biologist's conclusion about the archipelago, and finally reveals contradictory evidence that considers both salinity and temperature together.
Main Conclusion:
The marine biologist's argument is flawed because it fails to account for how temperature affects sea lice survival in the specific conditions of British Columbia.
Logical Structure:
The professor undermines the biologist's argument by showing that the biologist considered only one variable (salinity) while ignoring a crucial second variable (temperature) that completely changes the outcome when both factors work together.
Prethinking:
Question type:
Misc. - This is asking us to identify the method of reasoning the professor uses to challenge the biologist's argument. We need to figure out exactly HOW the professor undermines the biologist's conclusion.
Precision of Claims
The biologist makes a specific claim about sea lice transmission being unlikely during a specific timeframe (March-June) in a specific location (Broughton Archipelago) based on salinity levels alone. The professor's counter-evidence is equally specific - same salinity range plus temperature conditions in the same region.
Strategy
For method of reasoning questions, we need to identify what technique the professor uses. Looking at the structure: the biologist relies on studies about salinity alone, concludes that 25-30 parts per thousand will suppress sea lice. The professor then presents literature showing that salinity PLUS temperature (the missing factor) actually creates conditions where sea lice flourish. The professor is demonstrating that the biologist's reasoning is flawed because it ignored a crucial variable.
'pointing out that a condition claimed to be necessary for sea-lice survival is not sufficient for it' - This mischaracterizes what's happening. The professor isn't making a distinction between necessary vs. sufficient conditions. Instead, the professor is showing that the biologist's premise about unfavorable conditions is actually wrong when you consider the complete picture including temperature. The professor isn't discussing what conditions are necessary or sufficient for survival, but rather showing that the biologist's conclusion is contradicted by evidence.
'citing studies that suggest that salinity levels were not measured reliably' - This is incorrect because the professor doesn't question the measurement of salinity levels at all. The professor accepts that the salinity range is 25-30 parts per thousand, just as the biologist stated. The issue isn't with measurement reliability but with the interpretation of what those salinity levels mean for sea lice survival when combined with temperature.
'claiming that there is evidence showing that one of its premises is false' - This is exactly what the professor does. The biologist's premise is that salinities less than 30 parts per thousand are unfavorable to sea-lice survival. The professor presents literature review evidence showing that salinities of 25-30 parts per thousand (which falls in that 'unfavorable' range) actually favor sea lice flourishing when combined with cool spring temperatures. This directly contradicts and shows the falsity of the biologist's premise about what conditions are unfavorable to sea lice.
'questioning the reliability of the biologist's scientific sources' - The professor doesn't attack the reliability or credibility of the biologist's sources. Instead, the professor provides additional evidence from a literature review. The professor's strategy is to present counter-evidence, not to discredit existing sources.
'showing that its conclusion is inconsistent with its premises' - This would mean showing an internal logical contradiction within the biologist's own argument. However, the biologist's logic is internally consistent - if salinity below 30 is bad for sea lice, and the archipelago has 25-30 salinity, then sea lice should struggle there. The professor doesn't show internal inconsistency but rather shows that the premise itself is wrong when you consider additional factors.