Respuesta :
The scientific question could be that what is the effect of organisms like worms in the soil that aerate the soil, on plants that grow in the soil? An experiment could be made wherein the same plant is grown first without earth worms and then with earth worms for the same amount of time and then observe the plant growth to make a comparison or better yet, have two pots, with the same type of plant, one with the worms and one without for the same length of time and observe the differences in growth.
Check all correct elements below that you included in your question.
independent variable: presence of one species (here, worms)
dependent variable: effect on another species (here, lima bean plants)
relationship: benefit