Please use the following information to answer the question(s) below.
A scientist conducts an experiment to quantify the effect of mycorrhizae and soil nitrogen levels on plant growth in a grassland. The experiment has four treatments: (1) Mycorrhizae present and ambient levels of nitrogen, (2) mycorrhizae present and nitrogen added, (3) mycorrhizae absent and ambient levels of nitrogen, and (3) mycorrhizae absent and nitrogen added. After four weeks, the scientist removes the aboveground plant material for weighing. Figure 42.4.
-Figure 42.4 shows the results of the experiment. What is (are) the independent variable(s)?
A) nitrogen treatment only
B) biomass of aboveground plant biomass only
C) presence and absence of mycorrhizae
D) nitrogen treatment and whether mycorrhizae are present

Question

Please use the following information to answer the question(s) below.
A scientist conducts an experiment to quantify the effect of mycorrhizae and soil nitrogen levels on plant growth in a grassland. The experiment has four treatments: (1) Mycorrhizae present and ambient levels of nitrogen, (2) mycorrhizae present and nitrogen added, (3) mycorrhizae absent and ambient levels of nitrogen, and (3) mycorrhizae absent and nitrogen added. After four weeks, the scientist removes the aboveground plant material for weighing.  Figure 42.4.
-Figure 42.4 shows the results of the experiment. What is (are) the independent variable(s)?
A) nitrogen treatment only 
B) biomass of aboveground plant biomass only 
C) presence and absence of mycorrhizae 
D) nitrogen treatment and whether mycorrhizae are present

Quizplus · Accepted Answer

The independent variables in this experiment are both the nitrogen treatment (ambient or added) and the presence/absence of mycorrhizae. The graph shows the results of all four treatments, which differ based on these two independent variables. Therefore, the best choice is D.

Please Use the Following Information to Answer the Question(s) Below