Question

A scientist wanted to see if the fertilizer really helped their plant growth. They had twelve 3 week old rose bushes they had planted at the same time in their garden so they bought an organic fertilizer from Home Depot. For Rose bush 1 they added no fertilizer. For rose bush 2 through 12 they added 1/2 pound increments to each bush. Bush 2 received 1/2 pound, bush 3 1 pound, bush 4 1 1/2 pounds, and all the way up to bush 12 receiving 5 1/2 pounds. It was added to the base of each plant and then 3 weeks later the height of the bush was measured in centimeters. What is the independent variable(s)?

Answer 1

The independent variable in the experiment is the varying amounts of fertilizer added to each rose bush. The control is the bush with no fertilizer. The student's experiment with detergent has a flaw as it has more than one independent variable, as both detergent and sunlight exposure are being tested simultaneously.

Step-by-step explanation:

In the described experiment, the independent variable is the amount of fertilizer added to each rose bush. The independent variable is the one that is being changed or manipulated by the scientist to observe its effect on the dependent variable, which, in this case, is the growth of the plants. An accurate experiment requires at least one control group, which in this scenario is Rose bush 1, as it receives no fertilizer at all. This setup allows for comparison with the other bushes that received varying amounts of fertilizer.

The potential flaw in the student's experiment with detergent in the soil is that there are multiple independent variables being tested simultaneously: the presence of detergent and the amount of sunlight (with seed pots in the sun and others in the shade). This could confound the results, as both the detergent and sunlight exposure might influence plant growth. To conduct a controlled experiment accurately, all other conditions besides the independent variable should be kept constant, including light conditions, unless the variable of light is being systematically tested.