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Soru

Zorluk: Çok zorNecessary Assumption

Marine Biologist: The rapid proliferation of the invasive algae *Caulerpa taxifolia* in the Mediterranean basin has historically been driven by its ability to synthesize caulerpenyne, a toxin that severely deters indigenous herbivores. Recently, however, the algae's territorial expansion has stabilized despite an overall increase in regional water temperatures—a factor previously established to significantly accelerate the algae's general metabolic rate. Consequently, this unexpected stabilization must be the result of a severe localized depletion of essential benthic micronutrients required for the algae's structural growth.

Which one of the following is an assumption on which the marine biologist's argument depends?

  1. The acceleration of the algae's metabolic rate caused by increased water temperatures does not substantially compromise its ability to synthesize effective levels of caulerpenyne.Cevap
  2. B
    A severe localized depletion of essential benthic micronutrients is the only ecological condition capable of halting the territorial expansion of *C. taxifolia*.
  3. C
    Indigenous herbivores in the Mediterranean basin have developed absolutely no tolerance to the caulerpenyne toxin since the initial introduction of the algae.
  4. D
    The localized depletion of essential benthic micronutrients was not caused by the introduction of a competing invasive species.
  5. E
    The recent overall increase in regional water temperatures has been uniform across all depths where the invasive algae is currently present.

Cevap

The acceleration of the algae's metabolic rate caused by increased water temperatures does not substantially compromise its ability to synthesize effective levels of caulerpenyne.
This is a classic 'Defender' assumption that blocks a fatal alternative explanation. The author notes that the algae stabilized *despite* an increase in metabolic rate, assuming this increased rate is purely beneficial. However, if accelerating the metabolic rate somehow shut down the algae's ability to produce its protective toxin (caulerpenyne), indigenous herbivores would eat the algae, perfectly explaining the stabilization. By concluding the stabilization *must* be due to micronutrient depletion, the author is implicitly assuming this alternative scenario (loss of toxin production leading to herbivory) is not happening. Negating this option destroys the argument by providing that exact alternative cause.

Adım Adım Çözüm

1
Identify the conclusion of the argument.
The stabilization of the algae must be the result of a severe localized depletion of essential benthic micronutrients.
This is the final claim the author is attempting to prove, signaled by the word 'Consequently'.
2
Identify the premises supporting the conclusion.
Premise 1: The algae spreads because a toxin (caulerpenyne) deters herbivores. Premise 2: Expansion stabilized despite warmer water, which accelerates the algae's metabolic rate.
These are the facts provided to establish the context and rule out warmer water as a negative factor for the algae.
3
Determine the logical gap between the premises and the conclusion.
The author assumes that because warmer water generally accelerates metabolic rate, it acts purely as a positive factor for the algae. The author concludes micronutrient depletion is the ONLY explanation for the stabilization.
The argument fails to consider that the increased metabolic rate might have a negative side effect (like reducing toxin production) that could act as an alternative cause for the stabilization.
4
Apply the Negation Test to evaluate potential assumptions.
Negating the correct answer yields: 'The acceleration of the metabolic rate DOES substantially compromise its ability to synthesize effective levels of caulerpenyne.'
The Negation Test is the most reliable way to verify a necessary assumption. If the negated statement destroys the argument, the original statement is strictly required.
5
Analyze the impact of the negated statement on the conclusion.
If the toxin is compromised, herbivores can eat the algae. This explains why the expansion stabilized, providing an alternative cause and destroying the conclusion that it 'must' be due to micronutrient depletion.
Because the negated statement ruins the argument's causal claim, the original statement is a necessary assumption.

Anahtar Kavram

Necessary Assumption (Defender)
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Konular

Necessary Assumption

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