Your question is rather unclear but from what I can tell either there were not an even amount of Petri dishes or some of them were left open while others were not.
Explanation:
you must add activation energy to initially break the chemical bonds. Catalysts simply lower the activation energy needed to do the chemical reaction going. reactions to occur without themselves being used up in the reaction. Energy is usually needed to break the bonds and get the reaction going.
Answer:
The starfish is ecosystem balancer
Explanation:
Answer: Smooth muscle
Explanation:
I got it wrong on usatestprep and when it showed me the answer key, smooth muscle was the correct answer.