Answer :
Final answer:
The correct answer is 4) bile. Bile is the substance that contains no digestive enzymes, as it functions to emulsify fats in the digestion process rather than breaking them down chemically with enzymes.
Explanation:
The correct answer is 4) bile. The substance among the options that contains no digestive enzymes is bile. Bile is a digestive fluid that is produced by the liver, stored in the gallbladder, and released into the duodenum. It does not contain enzymes but is important for the digestion and absorption of fats because it contains bile salts, which emulsify fats. This allows pancreatic lipase, which is secreted by the pancreas into the small intestine, to more effectively break down fats into fatty acids and glycerol.
In contrast, saliva contains the enzyme amylase which begins carbohydrate digestion. Gastric juice, secreted by the stomach lining, contains pepsinogen (which is activated to pepsin in the stomach) to initiate protein digestion. Pancreatic juice is rich in digestive enzymes such as trypsin for protein digestion, pancreatic lipase for fat digestion, and amylase for further carbohydrate digestion. Intestinal juice, produced by the cells lining the small intestine, contains various enzymes for the final stages of digestion.