Astudent wants to answer the question “does adding calcium powder to soil make pea plants grow faster? ” she adds calcium powder to the soil of 12 plants and does not add it to the soil of a second group of 12 plants. she measures the growth of all of the plants in each group for a month. which statement best summarizes the factors that need to be controlled in this experiment?

1. which of the following is correct regarding opiates/opioids: a. they all have a natural component as a starting pointb. they have low addiction possibilitiesc. methadone binds to some of the same receptorsd. a and care correcte. all are correct

9. the history of life on earth is recorded in

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.