Biology Ecology & Environmental Interactions Flashcards

What is the ecological significance of decomposers in an ecosystem?

Answer: They recycle nutrients from dead organic matter back into the soil for reuse

Decomposers (bacteria and fungi) break down dead organisms and waste, releasing essential nutrients like nitrogen and phosphorus back into the soil.

The 'intermediate disturbance hypothesis' predicts that biodiversity is highest when

Answer: Disturbances occur at intermediate frequencies and intensities

Intermediate disturbance prevents competitive exclusion by dominant species while still allowing colonization, maximizing the number of coexisting species.

Which of the following best describes an r-selected species?

Answer: Rapid reproduction, many offspring, little parental care, unstable environments

R-selected species invest energy in producing many offspring quickly with little care, thriving in unpredictable environments where rapid colonization matters.

Acid rain primarily damages forest ecosystems by

Answer: Leaching essential nutrients from soil and releasing toxic aluminum ions

Acid rain lowers soil pH, washing away calcium and magnesium while releasing toxic aluminum, weakening trees and disrupting nutrient cycles.

Which of the following is an example of a positive feedback loop in climate change?

Answer: Melting Arctic permafrost releasing methane, which causes further warming

Permafrost thaw releases trapped methane, a greenhouse gas that accelerates warming, causing more permafrost to melt — a self-amplifying positive feedback.

In a symbiotic relationship where one organism lives inside or on a host and causes harm, this is classified as

Answer: Parasitism

Parasitism is a +/- relationship in which the parasite benefits at the expense of the host's fitness, though hosts are usually not immediately killed.

Island biogeography theory predicts that species richness on an island increases with

Answer: Larger island size and closer proximity to the mainland

MacArthur and Wilson's theory states that larger islands support more species (more habitat) and closer islands receive more immigrants from mainland source populations.