Why is it necessary to have both mechanical and chemical digestion?

In general, characteristics that an organism survive and reproduce become more common over time. what mechanism of evolution causes this?

Which best describes the nucleus of an atom a. it is where all of the particle s of the atom are located b. it is the negatively charged part of the atom c. it is where the electrons and the protons are located d. it is the part of the atom with the greatest mass

What do you need to use in order to work as an environmental scientist? you need to use the scientific method and__ in order to work as an environmental scientist.