Natural selection! In the theory of natural selection, those with less beneficial traits won't live to reproduce, but those with beneficial traits will be able to reproduce and pass on those traits to their offspring, which significantly increases the frequency of those beneficial traits.
Answer:
Yes. Cells have 'cell receptors' that are used to receive messengers like hormones to communicate. Cell receptors have specific shapes that fit the shape of the messenger that they want to receive. Organs like the pancreas send our these messengers to the cells to order them to do different functions.
