Which molecule would require a channel or a transport protein to cross the cell membrane

those molecules which are not lipid in nature and the uncharged substance such as oxygen carbon dioxide can move through the membrane without the help of transport protein

WHAT SUBSTANCES NEED HELP OF TRANSPORT PROTEIN

Ions, sugars, amino acids, and sometimes water cannot diffuse across the phospholipids

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).