Energy flow through food webs, population dynamics, and how species interact within an ecosystem — most of the concepts here connect back to one idea: energy moves in one direction, and it's lost at every step. Every question comes with a written explanation of the underlying ecological principle.
Only about 10% of energy at one trophic level is available to the next — the rest is lost as heat or used for the organism's own life processes, which is why food chains rarely extend past four or five levels.
Mutualism benefits both species involved; commensalism benefits one species while the other is unaffected — the difference is whether the second species gains anything at all, not just whether the relationship looks cooperative.
Carrying capacity is the maximum population an environment can sustain long-term, not the current population — a population can temporarily exceed carrying capacity before resource limits bring it back down.
Straight from the bank — one per difficulty tier. Reveal the answer to see the explanation you'd get in a real session.
In a food chain, if a producer contains 1,000 units of energy, approximately how much energy is available to the primary consumer that eats it?
A — 100 units. Roughly 10% of energy is transferred from one trophic level to the next; the rest is lost as heat or used by the producer's own life processes. 10% of 1,000 is 100 units. 500 units (C) applies a 50% transfer rate, far higher than the roughly 10% actually observed in real ecosystems.
A species of fish cleans parasites off a larger fish's skin, gaining food in the process, while the larger fish benefits from having parasites removed. What type of relationship is this?
A — Mutualism. Both species benefit — the cleaner fish gains food, and the larger fish gets its parasites removed — which defines mutualism. Commensalism (B) would only apply if one species benefited while the other was unaffected, but the larger fish is clearly benefiting too.
A population of rabbits in a field grows rapidly at first, but its growth rate slows and eventually levels off as food and space become limited. Which type of growth curve does this describe, and what is the population size at the point where growth levels off called?
A — Logistic growth; carrying capacity. A population that grows quickly at first and then slows as resources become limited, leveling off at a stable size, follows a logistic growth curve — and that stable leveling-off point is the carrying capacity. Exponential growth; carrying capacity (B) correctly names the leveling-off point but misidentifies the curve shape — exponential growth doesn't level off at all, it's the curve that describes unlimited growth before resource limits kick in.
Ecology questions reward knowing the vocabulary precisely — mutualism, commensalism, and parasitism sound similar but hinge on one specific difference each time.
For every species-interaction question, identify the effect on each species individually before choosing a term. Untimed practice is where that habit sticks.
Move to timed sessions once the relationship types and energy-flow rules are instant recall.
Pair ecology with plant biology in a mock — energy flow through an ecosystem starts with photosynthesis.
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