Conservation of Biodiversity · Paper 1 — Free Biology HL Practice Questions

In a coral reef ecosystem, an invasive predatory fish with no natural predators rapidly reduces the population of native herbivorous fish. Which of the following is the most likely long-term consequence for the reef?

A persistent pesticide is applied to a wheat field to control aphids. The pesticide is lipid-soluble and is not metabolised or excreted by organisms. The food chain the field is: $$\text{wheat} \rightarrow \text{aphids} \rightarrow \text{ladybirds} \rightarrow \text{sparrowhawks}$$ Which organism will have the highest concentration of pesticide per gram of body mass?

A fungal pathogen is introduced into a tropical rainforest, killing the dominant tree species. This tree provides fruit for 40 percent of bird species and nesting sites for 20 percent of mammal species in the ecosystem. Assuming this tree functions a keystone species, which outcome is most likely over the long term?