Ap Bio Lab Cellular Respiration Answers AP Bio Lab 5 Cellular Respiration One Quick Question!?

AP Bio lab 5 Cellular respiration one quick Question!? - ap bio lab cellular respiration answers

Hello I am the AP bio lab cell respiration, cell respiration activities in pea, pea sprouts, and glass beads. A question I can not explain.
Who respirometer 1, 2 or 3 (germinating seeds did not germinate, accounts), serves as a negative control? Explaining.
I think the bead is the right answer, because none of the cellular respiration ... But what is the point of use?