Proteins are an essential component of a healthy diet for humans (and other animals). their most common purpose is to serve as:

the answer is d. chordata

the fossil record provides evidence of a common ancestor to many species.

the atomic number of magnesium is 12. its nucleus must contain 12 protons and no electrons. the atomic number of an atom is determined by the number of protons.

magnesium is an electrolyte injection commonly used to treat low magnesium levels in your blood. it is also used to prevent or control seizures in women with preeclampsia or eclampsia.