Question

case study
the green river valley
the green river valley is home to a diverse ecosystem, including fish, amphibians, birds, small mammals, and a variety of plants. over the past decade, a new factory was built upstream, and chemical runoff began entering the river.
as a result:

• some fish populations declined sharply.
• frogs and other amphibians became less common.
• certain plants near the riverbank died off.
• birds and mammals that relied on fish or plants as food began moving away.

local scientists studied the area and found that the decline in one species caused a chain reaction, affecting multiple organisms and altering the structure of the ecosystem.
the community is now debating whether to implement stricter regulations to reduce pollution and restore the river ecosystem.

question 5/16
5 which of the following best describes what happened in the green river valley?
a only abiotic components of the ecosystem were affected
b the ecosystem became more diverse due to new species
c human activity disrupted the ecosystem, leading to biodiversity loss
d pollution had no effect on the species in the river

Explanation:

• Option A: The case shows biotic components (fish, amphibians, plants, etc.) were affected, so A is wrong.
• Option B: Populations declined and species became less common, so ecosystem became less diverse, B is wrong.
• Option C: A new factory (human activity) caused chemical runoff, leading to declines in species (biodiversity loss), which matches the case.
• Option D: The case clearly shows pollution (from factory runoff) affected species (fish, amphibians, etc.), so D is wrong.

Answer:

C. Human activity disrupted the ecosystem, leading to biodiversity loss