medium · Act science

A marine biologist hypothesizes that the density of a specific plankton species is highest in the 'sunlight zone' (0–200 m) and decreases significantly in the 'twilight zone' (200–1,000 m). Depth (m) | Plankton Density (count/m^3) 50 | 1,200 150 | 1,150 300 | 200 600 | 180 900 | 175 Does the evidence support this hypothesis?

1. Yes; there is a sharp drop in density once the depth exceeds 200 meters, separating the two zones.
2. No; the density is not constant within the sunlight zone, as it drops from 1,200 to 1,150 counts.
3. No; the density in the twilight zone is stable, whereas the hypothesis predicted it would reach zero.
4. Yes; the hypothesis is supported because the sunlight zone has more available light for the plankton to use.

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