IB Biology SL C4.1.17 Top Down Vs Bottom Up Control Questions

Predict predator-loss effects and trace indirect population changes across trophic levels using sea-otter and coyote food-web evidence in IB Biology SL C4.1.17.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Identify top-down control when predators regulate herbivores or lower trophic levels, and predict the resulting trophic cascade after predator loss or recovery.
  • Interpret a food web to trace indirect population changes across several trophic levels caused by predator abundance or removal.

IB Biology SL C4.1.17 Top Down Vs Bottom Up Control Questions question 1

[Maximum number: 1]

Humans have persecuted predators such as coyotes (Canis latrans), causing severe reduction in the number of large carnivores throughout the world. The diagram represents part of a food web in Texas, USA.

Figure for Question IB Biology SL C4.1.17 Top Down Vs Bottom Up Control Questions question 1 — IB Biology SL

What is a possible outcome for the lagomorph population in this ecosystem if coyote numbers were controlled by killing them to reduce losses of domestic livestock?

A

Decrease because there are fewer predators

B

Increase because there are fewer foxes to eat them

C

Decrease because there are more rodents for foxes to eat

D

Increase because, although there are more foxes, there are also more rodents

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