Eutrophication — Prelims Strategy

Prelims Strategy

Memorise the causal sequence, then test each step rather than treating every term as a synonym. Nutrients stimulate growth under suitable conditions; decomposition of organic material can increase oxygen demand; hypoxia depends on the balance with replenishment. Do not infer toxicity merely from a bloom.

For paired statements, distinguish concentration from load and surface appearance from whole-system conditions. A low concentration in a high-volume inflow may still represent a large input. A daytime oxygen reading does not settle night-time or deeper-water conditions. Look for the stated time and location of measurements.

When judging interventions, ask whether they remove symptoms, reduce continuing inputs or alter an ecological process. Each can have a role, but their outcomes differ. Review wrong options by identifying the specific missing condition or measurement. A useful self-test asks why more algae can coexist with less oxygen available to animals later; the answer should include respiration, decomposition and replenishment rather than a slogan.