Which statement correctly describes digestive enzymes and their substrates, including the influence of pH?

Which statement correctly describes digestive enzymes and their substrates, including the influence of pH?

• A. Amylase digests fats; proteases digest starch; lipases digest proteins; pH environments influence activity.
• B. Amylase digests nucleic acids; proteases digest carbohydrates; lipases digest proteins; pH determines color.
• C. Amylase digests starch; proteases digest proteins; lipases digest fats; pH environments influence activity.
• D. Amylase digests proteins; proteases digest fats; lipases digest starch; pH has no effect.

Answer: (C)

Digestive enzymes are highly selective for their substrates, and their activity is shaped by pH. Amylase targets starch (a carbohydrate), proteases target proteins, and lipases target fats. The pH of the environment influences enzyme activity by affecting the charge and shape of the active site; each enzyme has an optimal pH range, and moving away from that range reduces activity or denatures the enzyme. In digestion, this is why different parts of the digestive system provide different pH conditions to support the enzymes that work there. So describing amylase as acting on starch, proteases on proteins, and lipases on fats, with pH environments influencing activity, captures both substrate specificity and pH effects. Other statements mix up which substrates are acted on or say pH has no effect, which doesn’t fit how digestion works.

Digestive enzymes are highly selective for their substrates, and their activity is shaped by pH. Amylase targets starch (a carbohydrate), proteases target proteins, and lipases target fats. The pH of the environment influences enzyme activity by affecting the charge and shape of the active site; each enzyme has an optimal pH range, and moving away from that range reduces activity or denatures the enzyme. In digestion, this is why different parts of the digestive system provide different pH conditions to support the enzymes that work there. So describing amylase as acting on starch, proteases on proteins, and lipases on fats, with pH environments influencing activity, captures both substrate specificity and pH effects. Other statements mix up which substrates are acted on or say pH has no effect, which doesn’t fit how digestion works.