What is the function of villi and microvilli in the GI tract?

Correct Answer: D

Rationale: Villi and microvilli in the GI tract serve to increase the surface area of the small intestine, aiding in the absorption of nutrients into the bloodstream. Choices A, B, and C are incorrect as villi and microvilli are primarily involved in enhancing absorption, not in producing bile, killing bacteria, or producing vitamin K.

Correct Answer: B

Rationale: The correct answer is B: Emulsify fats in the small intestine. Bile emulsifies fats in the small intestine, breaking them down into smaller droplets that can be more easily digested by enzymes like lipase. Choice A is incorrect as fats are not digested in the stomach but rather in the small intestine. Choice C is incorrect as fats are transported through the lymphatic system instead of the circulatory system. Choice D is incorrect as fats are broken down into smaller components through emulsification, not splitting.

Correct Answer: C

Rationale: The correct answer is C: bicarbonate ions. Bicarbonate ions, secreted by the pancreas, neutralize the acidic chyme entering the small intestine from the stomach, creating a more suitable environment for digestive enzymes. Saliva (choice A) helps in the initial breakdown of food in the mouth, not in neutralizing stomach acid. Gastric mucus (choice B) protects the stomach lining from the acidic environment but does not neutralize the acid in the small intestine. Enzymes (choice D) facilitate chemical reactions in digestion but do not neutralize stomach acid.

Correct Answer: D

Rationale: Type 2 diabetes is characterized by insulin resistance, high blood glucose levels, and high blood insulin levels. Rapid destruction of the pancreas is not a feature of this condition. The destruction of pancreatic beta cells is more commonly associated with type 1 diabetes, not type 2 diabetes. Therefore, option D is the correct answer. Options A, B, and C are all characteristic features of type 2 diabetes, making them incorrect choices.

Correct Answer: D

Rationale: The correct answer is 'none of the above.' Human digestive enzymes like salivary amylase and pancreatic amylase cannot digest fiber. Instead, fiber is fermented by gut bacteria in the large intestine. Cellulase, which is an enzyme produced by some animals and microorganisms, can break down cellulose found in plants, but it is not a human digestive enzyme, making it an incorrect choice in this context.