I would say oxygen because respiration is breathing mechanically.
(C) the cell cycle is important and cell division divides the cell.
Answer:
It is similar because the nuclear envelope is a membrane similar to the cell membrane around the whole cell. There are pores and spaces for RNA and proteins to pass through while the nuclear envelope keeps all of the chromatin and nucleolus inside. When the cell is in a resting state there is something called chromatin in the nucleus.
Explanation:
Closely packed is like a sheet layer
