The activity of ptyalin is likely to decrease with an increase in the concentration of

The activity of ptyalin, which is an enzyme responsible for breaking down starch into simpler sugars, is likely to decrease with an increase in the concentration of acid. This is because ptyalin works best in a slightly alkaline environment, which means that it is most effective at breaking down starch when the pH is between 6.7 and 7.0. When acid is added to this environment, the pH decreases and becomes more acidic, which can denature or deactivate the enzyme. Therefore, an increase in the concentration of acid can disrupt the optimal pH range for ptyalin, causing a decrease in its activity and effectiveness in breaking down starch.