(a)(i) An agonist is a drug that mimics a natural messenger and activates the associated receptor for that messenger. Nicotine is an agonist for the acetylcholine receptor. (ii) A competitive antagonist is an antagonist whose degree of antagonism is directly related to the relative concentrations of the agonist and antagonist. This indicates that both the agonist and antagonist bind to the same site on the receptor or that the antagonist directly interferes with agonist binding. This is a dose-response curve illustrating the response to a single competitive antagonist. This is a dose-response curve of a competitive antagonist in the presence of an agonist(iii)A non-competitive antagonist is an antagonist whose action on the receptor is independent of the concentration of the agonist. This is because they bind to different sites in the receptor. This is a dose-response curve for a single non-competitive antagonist. This is a dose-response curve for a noncompetitive antagonist in the presence of an agonist(b) Chemical EnhancersA variety of chemicals have been studied as additives to improve the penetration of transdermal delivery. These can be classified as solvents, surfactants, fatty acids/esters and terpenes. These additives increase the permeability of the skin through various mechanisms, including increasing solubility and creating an easier pathway through the stratum corneum. Ionpheresis Ionpheresis is a small, low-current electric field that is applied to the skin in the area of ​​application of the medication. The mechanism of this application is believed to be electrophoresis or electroosmosis. This method has been shown to increase drug penetration by orders of magnitude at... middle of paper... eceptor occupancy reaches saturation. Compound C achieves a relatively lower response value of 40%, which is a typical result for a partial agonist.(iii) The statement cannot be proven with the information shown in the graph since compounds A and B are not tested for affinity.(iv) The statement is partially correct. The response of compound A is 100% at very low concentrations, meaning it produces a maximal response; however this is not related to receptor occupancy. We have no information on the employment/response relationship and full employment at all concentrations is impossible. Works CitedLane, DP and PM Fischer. "Turning the key to p53." Nature 427.6977 (2004): 789-90.Prausnitz, M.R., Mitragotri, S. and Langer, R. (2004), "Current status and potential future of transdermal drug delivery", Nature Reviews DrugDiscovery, 3, pp.115–124.