Where does the chemical digestion of starch begin?

Correct Answer: A

Rationale: The correct answer is A: mouth. Chemical digestion of starch begins in the mouth with the enzyme amylase present in saliva. Amylase breaks down starch into maltose. This process initiates the breakdown of complex carbohydrates into simple sugars for absorption. In contrast, the esophagus is not involved in digestion, the stomach primarily performs mechanical and protein digestion, and the small intestine is where most of the digestion and absorption of nutrients occur, but not where the initial digestion of starch begins.

Correct Answer: B

Rationale: The correct answer is B: producing enzymes. The pancreas produces digestive enzymes such as amylase, lipase, and protease that help break down carbohydrates, fats, and proteins in the small intestine. These enzymes are crucial for proper digestion and nutrient absorption. A: The pancreas does not produce bile. Bile is produced by the liver and stored in the gallbladder. C: The pancreas does not store nutrients. Nutrient storage mainly occurs in the liver and adipose tissue. D: The pancreas does not absorb vitamins. Vitamin absorption primarily takes place in the small intestine. In summary, the pancreas plays a vital role in digestion by producing enzymes that aid in the breakdown of food components.

Correct Answer: B

Rationale: The correct answer is B: lipase. Lipase is the enzyme responsible for breaking down fats into fatty acids and glycerol. Amylase (A) breaks down carbohydrates, trypsin (C) breaks down proteins, and pepsin (D) also breaks down proteins but in the stomach. Lipase specifically targets fats in the small intestine, aiding in their digestion and absorption. Therefore, lipase is the correct choice for breaking down fats, making it the most suitable answer among the options provided.

Correct Answer: C

Rationale: The large intestine's main role is to absorb water from the indigestible food residue, forming feces. This process helps maintain proper hydration levels in the body. It does not digest proteins (choice A) or absorb nutrients (choice B), as these processes primarily occur in the small intestine. The production of bile (choice D) is carried out by the liver and stored in the gallbladder, not by the large intestine. Thus, choice C is correct as it aligns with the primary function of the large intestine.

Correct Answer: C

Rationale: The correct answer is C: Digestion of lipids is not a function of saliva. Saliva primarily aids in cleaning the mouth by washing away food particles, killing bacteria with its antibacterial properties, and facilitating speech by lubricating the mouth and throat. Digestion of lipids primarily occurs in the small intestine with the help of enzymes like lipase. Salivary amylase, found in saliva, assists in breaking down carbohydrates, not lipids. Therefore, digestion of lipids is not a function of saliva.