The imidazole side chain of histidine can function as either a general acid catalyst or a general base catalyst becausea. the imidazole group has a pka in the physiological ph range. b. in the physiological ph range, the nitrogen in the ring can be easily protonated/deprotonated. c. one guanidino group is protonated, and the other is deprotonated at physiological ph. d. the imidazole group is a strong reducing agent at physiological ph.

To find the work done, the force exerted and distance moved are multiplied. a couch is moved twice before you are happy with its placement. the same force was used to move the couch both times. if more work is done the first time it is moved, what do you know about the distance it was moved? a) when more work was done, the couch was moved the same distance. b) when more work was done, the couch was moved less. c) when more work was done, the couch was moved further. d) when more work was done, the couch wasn't moved at all.