<prompt> Action of physiological uncoupler ?Inhibition of both ATP synthesis and ETCInhibition of ATP synthesis only not ETCInhibition of only ETC not ATP synthesisNone of the above  <response>: Ans. is b i.e., Inhibition of ATP synthesis only not ETC As the name suggests, these componds block the coupeling of oxidation with phosphorylation. These compounds allow the transfer of reducing equivalents in respiratory chain but prevent the phosphorylation of ADP to ATP by uncoupling the linkage between ETC and phosphorylation. Thus the energy instead of being trapped by phosphorylation is dissipated as heat. Uncouplers may be :? i Natural :- Thermogenin, thyroxine ii Synthetic :- 2, 4-dinitrophenol 2, 4-DNP, 2, 4-dinitrocresol 2, 4-DNC, and CCCP chlorocarbonylcyanidephenyl hydrazone. 