Final answer:
The response variable in the study to predict crop yield based on fertilizer application is the yield of the crop, as it is the dependent variable being measured. The amount of fertilizer is the independent variable that influences the yield. A control group without fertilizer is essential for a valid comparison in such an experiment.
Step-by-step explanation:
The response variable in the study that aims to determine if one can predict the yield of a crop based on the amount of fertilizer applied to the soil is the a. yield of the crop. This is because the yield is the outcome that is being measured or affected in the study (dependent variable), while the amount of fertilizer applied is the condition being changed or controlled to see its effect on the yield (independent variable).
When conducting an experiment to test the effect of fertilizer on plant growth, a control group is necessary for comparison. In a scenario where one row of corn is given fertilizer (test group) and another is not (control group), the row without fertilizer acts as the control, and both rows should receive the same amount of sun and water to ensure that any differences in growth are due to the presence or absence of fertilizer.
If other factors, such as the amount of water, soil quality, or amounts of sunlight, vary between the test and control groups, they can affect the experimental outcome and should be controlled to ensure a valid experiment.