Acknowledging that Nature is one unified whole, we expect that physics and biology are intimately related. Keeping in mind that physics became an exact science with which we are already familiar with, while, apparently, we do not have at present a similar knowledge about biology, we consider how can we make useful the clarity of physics to shed light to biology. The next question will be what are the most basic categories of physics and biology. If we do not want to cut laws of Nature into different parts, we obtain a constraint, and the remaining part of physics will be the input data to the equations of physics. In these terms, our question will be: if we keep biological laws intact, as indivisible units, what remains in case of biology? ...