A botanist conducted a study to investigate how different light wavelengths affect the growth rate of hydroponic sweet basil plants.
Sixty basil seedlings, all of the same cultivar and age, were selected. Before the treatments began, the botanist recorded the initial wet biomass of each seedling.
The 60 seedlings were then randomly allocated to three environmental chambers with 20 seedlings in each:
The temperature, humidity, and nutrient solution levels were kept constant across all chambers. At the end of a 30-day cultivation period, the botanist recorded the final wet biomass for each plant. The results showed that the average increase in biomass for the plants in Chamber A and Chamber B was significantly higher than those in Chamber C.
Identify the independent variable in this study.
Practise AQA A Level Psychology Scientific processes with exam-style questions for A Level Psychology. 100 questions, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.