[Campbell Biology P.957] The text states that pepsin is resistant to low pH, allowing it to ... | Practice Question

The text states that pepsin is resistant to low pH, allowing it to function in the acidic stomach. Based on this, which of the following is most likely an adaptation of digestive enzymes functioning predominantly in the small intestine?

  • A: They are optimized to function at a very low pH, similar to the stomach.
  • B: They are designed to operate optimally in a neutral to slightly alkaline environment.
  • C: They are typically secreted in an inactive form and activated by stomach acid.
  • D: They are primarily responsible for breaking down large food particles, not macromolecules.

Explanation

Pepsin functions in the highly acidic stomach. The small intestine, in contrast, has a neutral to slightly alkaline environment due to the release of bicarbonate from the pancreas. Therefore, digestive enzymes functioning predominantly in the small intestine, such as pancreatic amylases, lipases, trypsin, and intestinal disaccharidases, must be adapted to function optimally in this less acidic, more neutral to alkaline pH range.