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Biologists studying deep-sea ecosystems have found that all species of tube worm native to the Abyssal Ridge rely exclusively on chemosynthetic bacteria for energy. Furthermore, any organism that relies exclusively on chemosynthetic bacteria for energy lacks a functional digestive tract. Recently, researchers have also documented that some species of tube worm native to the Abyssal Ridge form symbiotic relationships with bioluminescent fungi.

Which of the following must be true based on the statements above?

  1. At least some organisms that form symbiotic relationships with bioluminescent fungi lack a functional digestive tract.Answer
  2. B
    Any organism in these deep-sea ecosystems that lacks a functional digestive tract must rely exclusively on chemosynthetic bacteria for energy.
  3. C
    Most species of tube worm that form symbiotic relationships with bioluminescent fungi are native to the Abyssal Ridge.
  4. D
    Species of tube worm that are not native to the Abyssal Ridge possess a functional digestive tract.
  5. E
    Bioluminescent fungi found on the Abyssal Ridge do not rely on chemosynthetic bacteria for their own energy.

Answer

At least some organisms that form symbiotic relationships with bioluminescent fungi lack a functional digestive tract.
The correct answer accurately synthesizes the premises. The stimulus establishes a chain: all Abyssal Ridge tube worms rely on chemosynthetic bacteria, and anything relying on chemosynthetic bacteria lacks a functional digestive tract. This means every Abyssal Ridge tube worm lacks a functional digestive tract. We are also told that some Abyssal Ridge tube worms form symbiotic relationships with bioluminescent fungi. These specific tube worms, therefore, have both traits: they have the symbiotic relationship AND they lack a functional digestive tract. Thus, it must be true that at least some organisms with this symbiotic relationship lack a functional digestive tract.

Step-by-Step Solution

1
Identify the conditional statements (the 'all' and 'any' premises).
1. Native to Abyssal Ridge -> Rely on chemosynthetic bacteria. 2. Rely on chemosynthetic bacteria -> Lacks functional digestive tract.
Mapping absolute conditional relationships is the first step in deduction.
2
Chain the conditional statements together.
Native to Abyssal Ridge -> Lacks functional digestive tract.
Since relying on chemosynthetic bacteria is the necessary condition in the first premise and sufficient in the second, they can be linked.
3
Incorporate the overlapping 'some' statement.
Some species native to the Abyssal Ridge form symbiotic relationships with bioluminescent fungi.
Quantifier statements ('some') provide specific instances where the general conditional rules apply.
4
Combine the 'some' statement with the chained conditional rule.
Because those 'some' tube worms are native to the Abyssal Ridge, they must lack a functional digestive tract. Therefore, some organisms with bioluminescent fungi relationships lack a functional digestive tract.
Whatever characteristics apply to all members of a group must also apply to any specific subset of that group.

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