← Back to Test

Problem 6 - Entrance Test

An experiment investigated the impact of different fertilizers on the biomass production of a specific algae species. Researchers cultivated algae in identical tanks, varying only the fertilizer type (Fertilizer X, Y, or Z) and including a control group (no fertilizer). After two weeks, the dry biomass of algae was measured. The results are presented in a table. | Group | Fertilizer Type | Average Algae Dry Biomass (mg) | |---|---|---| | 1 | Control (None) | 150 | | 2 | Fertilizer X | 280 | | 3 | Fertilizer Y | 210 | | 4 | Fertilizer Z | 320 | What is the independent variable in this experiment?

Correct: B

The independent variable is the factor that is intentionally changed or manipulated by the experimenter. In this experiment, the researchers varied the 'Fertilizer Type' to observe its effect on algae growth. The algae dry biomass is the measured outcome (dependent variable). Cultivation duration and tank size are controlled variables, kept constant to ensure a fair test.