Answer:
I don't think you'll understand this but...
Explanation:
Think of it as Evolving A Pokemon.
If that doesn't help go to google type in your question (Make sure its simple) And it should Give you a simple answer.
An adult , or mature i think sry if not the answer you were looking for
Mitochondria- it produces the energy for the cell. the muscle needs more energy because they are always functioning
Photosynthesis, ocean absorption, and fossilization are carbon sinks. Combustion and respiration are carbon sources