Question

experimental group: seedlings grown with coffee grounds; control group: seedlings grown without coffee grounds; dependent variable: seedling height; independent variable: empty; answer bank: light, soil, temperature, seedlings given extra water; would it be a good experimental design if she also, as part of the same experiment, tests seedling growth at different temperatures by growing one group at 20 °c (68 °f) and the other group at 25 °c (77 °f)? yes, but it is not necessary to grow one group without coffee since that is not being tested. yes, it would enable her to compare more than one environmental factor at a time. no, the other conditions should remain the same for the experiment to be scientifically sound. no, a temperature difference of 5 °c is not large enough to detect a significant temperature effect.

Explanation:

In a scientific experiment, to accurately determine the effect of a single variable (here, coffee - grounds on seedling growth), all other conditions should be kept constant. Changing the temperature while also testing the effect of coffee - grounds would introduce another variable, making it difficult to determine which variable is causing any observed changes in seedling height.

Answer:

No, the other conditions should remain the same for the experiment to be scientifically sound.