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Difficulty: MediumExplicit Details

The bombardier beetle (*Brachinus crepitans*) possesses a unique defensive mechanism to deter predators. Within its abdomen are two separate chambers containing different chemical compounds: hydroquinones and hydrogen peroxide in one, and a mixture of catalytic enzymes in the other. When threatened, the beetle contracts muscles that force the contents of the first chamber into the second. The resulting rapid chemical reaction produces a boiling, noxious liquid that the beetle can spray from the tip of its abdomen. This spray reaches temperatures of nearly 100 degrees Celsius and can be aimed in almost any direction, successfully repelling attackers.

Based on the text, which statement is true of the chemicals stored in the bombardier beetle's abdomen?

  1. A
    They are maintained at a temperature of nearly 100 degrees Celsius prior to being mixed.
  2. B
    They are synthesized by the beetle only after a threat has been identified.
  3. They are housed in two distinct chambers before the beetle releases them.Answer
  4. D
    They trigger the muscle contractions that initiate the chemical reaction.

Answer

The chemicals are housed in two distinct chambers before the beetle releases them.
The correct answer is supported by the text's statement that the beetle's abdomen contains 'two separate chambers containing different chemical compounds' prior to the reaction.

Step-by-Step Solution

1
Analyze the question stem to identify the target subject.
The question asks for a true statement about the chemicals stored in the bombardier beetle's abdomen based on explicit details in the text.
This establishes the criteria for finding the correct option, which must be directly supported by the passage without requiring any logical leaps or speculation.
2
Locate the portion of the text that describes the storage of chemicals in the abdomen.
The text states: 'Within its abdomen are two separate chambers containing different chemical compounds: hydroquinones and hydrogen peroxide in one, and a mixture of catalytic enzymes in the other.'
This sentence provides the explicit facts about how the chemicals are arranged and stored before the reaction.
3
Evaluate the answer choices against the located detail.
The option stating that the chemicals are housed in two distinct chambers before release directly matches the text's description of 'two separate chambers containing different chemical compounds.' Other options misread details regarding temperature, speculate on synthesis timing, or mischaracterize the causal relationship between muscle contraction and the chemical reaction.
This confirms the correct option while eliminating the distractors.

Key Concept

Explicit Details
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