How do we call the maximal tissue response to a drug divided by the full agonist's maximal response (same receptors)?

There are 4 different receptor states.

Agonist is a ligand that binds to the inactivated conformation of the receptor and stabilizes it there

Which of the following is NOT a mechanism leading to decreased drug response?

For which of the below antagonists we have a rightward parallel shift of the agonist's dose-response curve?

Schild' s equation depends only on the identity of the antagonist and not of the agonist.