Biology Ecology & Environmental Interactions Flashcards

Eutrophication of a lake is most directly caused by

Answer: Excess nutrient runoff stimulating algal blooms

Excess nitrogen and phosphorus from agricultural runoff cause algal blooms; when algae die, decomposition depletes oxygen, creating dead zones.

Which of the following is an example of a density-dependent limiting factor?

Answer: Disease spreading more rapidly in a crowded population

Density-dependent factors like disease, predation, and competition intensify as population density increases.

In an ecological pyramid of biomass, which level always has the greatest biomass?

Answer: Producers

Producers (plants) form the base of the biomass pyramid because energy and mass decrease at each successive trophic level.

Which relationship exists between clownfish and sea anemones, where both organisms benefit?

Answer: Mutualism

Clownfish gain protection from the anemone's stinging tentacles, while the fish's movement aerates the anemone and removes parasites — a mutualistic relationship.

The reintroduction of wolves to Yellowstone National Park caused changes that eventually led to stabilization of riverbanks through a process called

Answer: A trophic cascade

Wolves reduced elk overgrazing of vegetation near rivers, allowing plants to regrow and stabilize banks — a classic trophic cascade effect.

Which process in the carbon cycle involves the release of CO2 from the burning of ancient organic matter?

Answer: Combustion of fossil fuels

Burning fossil fuels releases carbon stored over millions of years back into the atmosphere as CO2, disrupting the natural carbon cycle.

Resource partitioning among competing species in the same habitat is an example of

Answer: Character displacement reducing direct competition

Character displacement occurs when competing species evolve different traits to use different resources, reducing direct competition and allowing coexistence.