Final answer:
In the experiment evaluating fertilizers Magic Grow and Uncle Ben's Secret Blend, the independent variables include the type and amount of fertilizer, as well as the plant species, while the dependent variable is plant growth. A control group without fertilizer is used for comparison, and factors like water, sunlight, and temperature are held constant.
Step-by-step explanation:
Controlled Experiment Variables
In a controlled experiment evaluating two fertilizers, independent variables include the type of fertilizer (Magic Grow or Uncle Ben's Secret Blend), the amount of fertilizer used, and the plant species used for testing. An experiment such as this aims to test how the dependent variable, which is the growth of the plants, is affected by the different independent variables.
A control experiment may be an additional setup where no fertilizer is applied to the plants to serve as a baseline for comparison. Other factors, which could be considered as controlled variables, should be kept consistent for all plants, such as the amount of water, sunlight, and temperature they are exposed to. The primary purpose of the experiment is to evaluate the effectiveness of the fertilizers on plant growth.
In this scenario, variables such as the amount of water, the amount of sunlight, the soil temperature, and others, should be kept constant to ensure that differences in plant growth are due to the fertilizers' effects rather than external factors.