IB Biology SL C4.1.16 Predator Prey Relationships Questions

Trace prey and predator changes, density-dependent feedback, time lags and recovery after predator removal in IB Biology SL C4.1.16.

Exam points

Interpret predator–prey population data to describe how predator abundance or removal changes prey density over time.
Explain density-dependent predator–prey feedback, including prey availability, predator response and time-lagged cycles or recovery after predator removal.
Evaluate field or experiment evidence to compare predation with competition and judge effects on species distribution, resistance or extinction risk.

[Maximum number: 2]

The sea snail Nucella ostrina and the sea star Pisaster ochraceus are predators of the mussel Mytilus trossulus. The mussels live on rocks at the edge of the sea and feed on phytoplankton and zooplankton. The zooplankton feed on the phytoplankton.

Nucella ostrina

Pisaster ochraceus

Mytilus trossulus

Groups of 50 mussels were transplanted to an experimental area and protected from predation until the start of the experiment. Researchers then investigated the effect of the predators on the population of the mussels over a period of 60 days.

Figure for Question IB Biology SL C4.1.16 Predator Prey Relationships Questions question 1 — IB Biology SL

Compare and contrast the effects of the predators on the population of the mussels.

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IB Biology SL C4.1.16 Predator Prey Relationships Questions question 1