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Difficulty: MediumMust Be True Questions

All amphibians that inhabit the alpine tundra rely on the nectar of the *Saxifraga* plant during their larval stage. Most species that rely on *Saxifraga* nectar during their larval stage are capable of surviving sub-zero temperatures. Furthermore, any species capable of surviving sub-zero temperatures possesses elevated levels of blood glucose.

Based on the information provided, which of the following must be true? (Select all that apply)

  1. Most species that rely on the nectar of the *Saxifraga* plant during their larval stage possess elevated levels of blood glucose.Answer
  2. B
    At least some amphibians that inhabit the alpine tundra possess elevated levels of blood glucose.
  3. Any species that does not possess elevated levels of blood glucose is not capable of surviving sub-zero temperatures.Answer
  4. D
    Any species that does not inhabit the alpine tundra does not rely on the nectar of the *Saxifraga* plant during its larval stage.
  5. E
    Any species that possesses elevated levels of blood glucose is capable of surviving sub-zero temperatures.

Answer

The correct statements are that most species relying on the nectar possess elevated blood glucose, and that any species lacking elevated blood glucose cannot survive sub-zero temperatures.
The correct statements are derived from valid logical rules. One is proven by chaining a 'most' premise directly into an 'all' premise, establishing that most nectar-reliant species possess elevated blood glucose. The other is proven by correctly forming the contrapositive of the final premise, establishing that lacking elevated blood glucose guarantees a species cannot survive sub-zero temperatures.

Step-by-Step Solution

1
Diagram the formal logic presented in the stimulus.
1. Alpine Tundra Amphibians -> Rely on Saxifraga Nectar. 2. Rely on Saxifraga Nectar -[most]-> Survive Sub-zero Temperatures. 3. Survive Sub-zero Temperatures -> Elevated Blood Glucose.
Mapping conditional and quantified statements clarifies the relationships and allowable deductions.
2
Evaluate combined logical inferences based on the diagram.
By linking statements 2 and 3, we can deduce that since most nectar-reliant species survive sub-zero temperatures, and ALL species that survive sub-zero temperatures possess elevated blood glucose, most nectar-reliant species must possess elevated blood glucose.
Chaining a 'most' statement with an 'all' statement yields a valid 'most' deduction.
3
Form contrapositives of the absolute conditional statements.
Contrapositive of 1: Do not rely on Saxifraga nectar -> Not an Alpine Tundra Amphibian. Contrapositive of 3: No elevated blood glucose -> Cannot survive sub-zero temperatures.
Contrapositives are always logically equivalent to the original conditional statements and are frequently tested in Must Be True questions.
4
Evaluate the given choices against the deduced truths to identify the correct answers.
The choice stating most nectar-reliant species possess elevated blood glucose matches our chained inference. The choice stating species without elevated blood glucose cannot survive sub-zero temperatures matches the contrapositive of statement 3.
Comparing choices to mathematically proven deductions ensures we select only the statements that are 100% supported by the text.

Key Concept

Chaining formal logic and forming contrapositives to determine valid deductions.
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