Question

Difficulty: MediumLogical Inferences

In subalpine forests, wood-boring beetle larvae excavate tunnels that facilitate fungal colonization and accelerate log decomposition. However, ecologist Elena Rostova hypothesized that in arid environments, low humidity desiccates tunnel interiors, inhibiting fungal growth and negating this decomposition effect. Rostova's team compared decomposition rates of logs with and without tunnels across humid and arid subalpine zones. They found that in the arid zone, logs with tunnels decomposed at the same slow rate as those without tunnels, whereas in the humid zone, logs with tunnels decomposed significantly faster. Which choice most logically completes the text?

  1. A
    beetle larvae are unable to excavate tunnels in logs that are located in arid subalpine environments.
  2. B
    wood-boring beetle larvae are the primary regulators of organic decomposition rates across all terrestrial ecosystems.
  3. C
    beetle larvae in arid environments alter their tunneling depth to seek out higher levels of moisture within the logs.
  4. the accelerating effect of beetle larvae on log decomposition depends on environmental humidity to prevent the desiccation of the tunnels.Answer

Answer

The accelerating effect of beetle larvae on log decomposition depends on environmental humidity to prevent the desiccation of the tunnels.
The passage explains that wood-boring beetle larvae accelerate log decomposition by creating tunnels that facilitate fungal colonization. The researchers hypothesized that this effect would be negated in arid environments due to low humidity drying out the tunnels and preventing fungal growth. Their experiment confirmed this, showing that logs with tunnels decomposed faster only in the humid zone, but not in the arid zone. Therefore, the logical conclusion is that the larvae's ability to accelerate decomposition relies on sufficient environmental humidity to prevent tunnel desiccation.

Step-by-Step Solution

1
Identify the primary mechanism of log decomposition described in the passage.
The passage establishes that wood-boring beetle larvae create tunnels that help fungi colonize logs, which in turn accelerates decomposition.
Understanding this baseline relationship is necessary to trace how climate factors interfere with the process.
2
Analyze the effect of the experimental variable (humidity) on this mechanism.
Low humidity in arid zones is hypothesized to desiccate tunnels and inhibit fungal growth, thereby neutralizing the decomposition-promoting effect of the larvae.
This step determines the predicted consequence of changing the environmental conditions.
3
Evaluate the experimental results to find the most direct logical conclusion.
Logs with tunnels decayed faster only in the humid zone, but decayed at the same slow rate as tunnel-less logs in the arid zone, supporting the hypothesis.
This step synthesizes the hypothesis and results to draw a conclusion supported by the text without introducing external assumptions.

Key Concept

Logical Inferences
Rate this question