Logical reasoning PrepTest 134 · Section 1 · Question 8

Incorrect. This answer highlights the plants—the bottom of the ecosystem—determining the outcome for something higher up on the food chain, so this answer reinforces the theory.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:
Bottom-Up Theory - Plants determine herbivores determine predators, so plants are the driver of population
Implication - Reduction in predator populations won't change much

Answer Anticipation:
The stimulus lays out a prediction based on the Bottom-Up Theory—if the predator population changes, then there should be little impact on the rest of the ecosystem. In order to weaken the theory, then, the correct answer will likely bring up a scenario that shows that prediction not happening—a predator population going down without it affecting the rest of the ecosystem.

Answer Explanation:
This answer shows a predator population changing, and the ecosystem also changing as a result. That violates the prediction made that predator population decreases should have "little impact" on the rest of the ecosystem, so it weakens the theory that makes that prediction.

Key Takeaway:
Theories/hypotheses are meant to describe phenomenon, and they're used to predict outcomes. If those predictions don't come true, then that theory/hypothesis is weakened.

Incorrect. This answer shows a change in the population from the bottom of the food chain having effects higher up on the food chain, so it reinforces the Bottom-Up Theory.

Incorrect. If anything, this answer aligns with the Bottom-Up Theory by showing that a change not affecting the availability of edible plants didn't change herbivore populations.

Incorrect. Since there's been no change to the predator population, this answer doesn't undercut the theory. It's unclear what effect it has on the theory but, if anything, it aligns with it by showing that a thriving edible plant population can stabilize a population of animals that eat them despite extensive hunting.