A scientist wants to determine if a new fertilizer helps bean plants grow taller. In her controlled experiment, which of the following must be kept consistent for all plant groups?

The final height of the bean plants.

The type of fertilizer given to each plant.

The amount of water and sunlight.

The scientist's prediction about the results.

What is the primary purpose of conducting a controlled experiment in a scientific investigation?

To use as many different variables as possible to see what happens.

To ensure the experiment produces the expected or desired outcome.

To make the experimental process faster and more cost-effective.

To isolate the effect of one specific variable by keeping other conditions constant.

The changing crank speed is an uncontrolled variable that also affects brightness.

The light bulb is likely burned out from the start.

Hand-crank generators are not meant to be tested scientifically.

The experiment was not conducted for a long enough period.

The experiment will take much longer to complete.

The equipment is more likely to break down.

It becomes impossible to reliably link a specific cause to an observed effect.

The results are guaranteed to support the original hypothesis.

To summarize the final conclusions of the experiment.

To provide a step-by-step guide for ensuring the test is consistent and repeatable.

To list the potential financial costs and budget for the research.

To be the initial hypothesis that the experiment is designed to test.