Problem 8 - Biology: The Dynamic Science

Question

The liver's role in digestion is to: a. synthesize aminopeptidase and dipeptidase to digest polypeptides. b. synthesize lipase to form free fatty acids. c. secrete trypsin to break the bonds in polypeptides. d. secrete bile and bicarbonate ions to help emulsify fats. e. store bile between meals.

Step-by-Step Solution

Answer

The correct answer is option d: The liver's role in digestion is to secrete bile and bicarbonate ions to help emulsify fats.

Step 1: Understand the roles of various substances in digestion

Aminopeptidase and dipeptidase are enzymes that help break down proteins, but they are not synthesized by the liver. Lipase also aids in the breakdown of dietary fats into smaller molecules, but it is not produced by the liver either. Trypsin is another enzyme involved in protein digestion but this is secreted by the pancreas, not the liver. Bile, on the other hand, is made by the liver and it aids in the emulsifying, or breaking down, of fats so they can be further digested and absorbed by the intestines. Bicarbonate ions neutralize the acidic contents from the stomach.

Step 2: Match the functions defined to the liver

Based on the understanding of the roles of these substances and enzymes in digestion, the ones associated with the liver are the secretion of bile and possibly the secretion of bicarbonate ions.

Step 3: Choose the correct option

The option that correctly relates to the functions of the liver in digestion is option (d), 'secrete bile and bicarbonate ions to help emulsify fats.'