Biology Ecology & Environmental Interactions Flashcards

Which of the following best describes a keystone species?

Answer: A species whose removal causes dramatic ecosystem change disproportionate to its abundance

Keystone species have outsized ecological roles; their removal triggers cascading changes far beyond what their population size would suggest.

In a food web, secondary consumers are organisms that

Answer: Eat primary consumers

Secondary consumers occupy the third trophic level, feeding on primary consumers (herbivores).

The nitrogen cycle is critical to ecosystems primarily because nitrogen is

Answer: An essential component of amino acids and nucleic acids

Nitrogen is a core element of proteins and DNA, making its cycling through ecosystems vital for all living organisms.

Which term describes the gradual process by which a bare rock surface develops into a mature forest community?

Answer: Primary succession

Primary succession begins on lifeless substrates like bare rock where no soil exists, starting with pioneer species like lichens.

An organism that benefits from a relationship while its host is neither helped nor harmed is engaged in

Answer: Commensalism

Commensalism is a +/0 relationship where one species benefits and the other experiences no significant effect.

What happens to energy as it moves from one trophic level to the next in an ecosystem?

Answer: About 90% is lost, primarily as heat

The 10% rule states that roughly 10% of energy is passed to the next trophic level; the rest is lost as heat through cellular respiration.

Which biome is characterized by permafrost, extremely low temperatures, and low biodiversity dominated by mosses and lichens?

Answer: Tundra

The tundra biome features permanently frozen subsoil (permafrost), a short growing season, and vegetation limited to low-growing plants.