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Science · Biology

Ecology & Biodiversity

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.

Practise ecology & biodiversity nowSee sample questions
3
Difficulty tiers
30s
Target pace
58%
Average first-attempt score

What's covered

  • Trophic levels and energy flow — track energy from producers through primary, secondary, and tertiary consumers, losing roughly 90% of it at each transfer.
  • Food chains vs. food webs — recognize that a food web shows the full network of feeding relationships in an ecosystem, while a food chain isolates just one linear path through it.
  • Population dynamics — distinguish exponential growth (unlimited resources) from logistic growth (limited by carrying capacity), and identify limiting factors that slow growth.
  • Species interactions — classify a relationship as predation, competition, mutualism, commensalism, or parasitism based on how each species is affected.
  • Biodiversity and ecosystem stability — connect higher species diversity to greater ecosystem resilience against disturbance.

Where students lose marks

Assuming energy transfer between trophic levels is efficient

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.

Mixing up mutualism and commensalism

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.

Confusing carrying capacity with population size

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.

Three sample questions

Straight from the bank — one per difficulty tier. Reveal the answer to see the explanation you'd get in a real session.

Sample 01Foundation

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?

Sample 02Core

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?

Sample 03Advanced

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?

How to practise this

Ecology questions reward knowing the vocabulary precisely — mutualism, commensalism, and parasitism sound similar but hinge on one specific difference each time.

State who benefits and who's affected before naming the relationship

For every species-interaction question, identify the effect on each species individually before choosing a term. Untimed practice is where that habit sticks.

Then 30 seconds a question

Move to timed sessions once the relationship types and energy-flow rules are instant recall.

Fold into a mock

Pair ecology with plant biology in a mock — energy flow through an ecosystem starts with photosynthesis.

Stop guessing the relationship.
Start naming who benefits.

  • A relationship-by-relationship walkthrough on every item
  • Timed or untimed sessions, any length you like
  • Tracked separately — see your ecology and biodiversity accuracy and pace over time
Start practising free

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