It is important because the results would not be reliable since other variables you are not testing could have been in affect.
Hope this helps(;
<em>The answer Is B.) It would have a shorter Stem</em>
Explanation:
The end result is glucose, with oxygen being the waste product. The two processes are similar in that they both produce energy, albeit in two different forms. They are different in that photosynthesis assembles the glucose molecule, while cellular respiration takes it apart.