The liter is a measurement of what quantity

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

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.