Which activity can only be done by a transmembrane protein?

A trans membrane protein is a type of integral protein that is found in the entire cell membrane and the membrane protein is attached to the cell membrane.

Many trans membrane proteins functions as channel or gateway which allows the transport of the specific materials which cannot be transported through other means.

The other materials which cannot be transferred by simple diffusion, osmosis or other means is transported by the trans membrane proteins.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.