WAEC Biology 2010 Papers

Concept:Stomach enzymes like renin and pepsin require an acidic environment to act efficiently.Explanation:The stomach secretes hydrochloric acid, which creates a strongly acidic medium.Both renin and pepsin show maximum activity at a low pH.Their optimum pH is around $\mathrm{pH}\ 2$.At higher pH values such as $\mathrm{pH}\ 7$, $\mathrm{pH}\ 8$, or $\mathrm{pH}\ 9$, the acidic medium is lost and enzyme action decreases.Thus, the most suitable pH for these enzymes is $\mathrm{pH}\ 2$.Answer:A. $\mathrm{pH}\ 2$