Question

Julie wants to know if adding calcium fertilizer to tomato plants will help prevent a disease of tomato plants called blossom-end rot. She uses 10 tomato plants. She put 5 plants in a sunny part of the garden and gives each one calcium fertilizer once a week. She places the other 5 plants in a shady part of the garden and gives them calcium fertilizer twice a week. She observes the 10 plants for 3 months to see if the fertilizer helped prevent blossom-end rot. Based on her experiment design, Julie's results are probably reliable. True False

Answer 1

It's not true.

The crucial principle for a scientific experiment is to keep only ONE variable at a time.

In this case, the variable of this experiment is actually the tomato is in sunny part or in shady part, instead of whether applying Ca fertilizer.