Energy stored in food can be used by cells to add a phosphate group to ADP to make ATP. This cycling of ATP to ADP occurs in a metabolic process called cellular respiration. phosphate group breaks, and energy is released. ATP becomes ADP, and the cycle of storing and releasing energy continues until the cell dies.
The DNA has to replicate before mitosis to keep the number of chromosomes consistent. Hope this helps.
Tissues form organ and organ forms organ systems,then it’s a complete organism
