Your answer is Enamel it is the coating on teeth that helps prevent damage.
One type of landform formed by wind would be sanddunes. This is the only landform I can think of formed by wind. The wind blows the sand along so that it builds up into a dune perhaps when it hits an obstacle like a small rocky spur and whole deserts can be converted into dunes.
You need to set it up write so you don't ruin your eye siggt
Functions of cell surface Receptors .
most ligands responsible for cell-cell signaling ( including neurotransmitters, peptide, hormones, and growth factors) bind to receptors on the surface of their target cells.