<u><em>Prophase is the stage of cell cycle which receive the signal to start cell division. Due to this signal, the nucleus dissolves inside the cell and the chromosomes begin movement to the middle line of the cell where these chromosomes condenses and then division of the cell occurs in later steps of mitosis cell division. So we can conclude that prophase step started when it got signal.</em></u>
All organisms need energy to survive. This is supplied through photosynthesis or from consuming another being in the form of calories (Yes, calories are a form of energy).