Scientists were monitoring the biochemical properties of a proton transporter by comparing the pH inside & outside the cell in the presence or absence of ATP. They noticed that the pH of the solution outside of the cell went down when ATP was added. Explain (a) whether the transporter used active or passive transport, (b) the direction of movement of the proton (H+), and (c) whether the reaction was endergonic or exergonic

a; The transporter used Active transport. This is an endegonic process that requires the use of ATPs as sources of energy,. and abundant oxygen to transport ions from region of lower concentration gradient to region of high concentration gradient , that is against their individual concentration gradient. It is a transport mechanism that is inhibited by hypoxia, cyanide, mercury compounds.

Therefore if the pH of the outside is lowered (more acidity),when ATP was introduced, then protons must have been pumped outwards from the internal cell layers, that is more protons are now outside than inside of the cells. Thus the outside should have higher concentration gradient than inside.

Consequently, protons are pumped ,against their concentration gradients, by active transports, and the fact that this occurred when ATPs was introduced showed that active transporter is the answer because energy is needed for it operates.

b. pH decreases with increase in acidity of a medium. The drop in the extracellular pH showed that the active transporter pumps protons from inwards to outward solution of the cells environments.

c. Endergonic because it involved use or consumption of energy as ATP as described above; an not the release.