_____ neutralizes stomach acid in the small intestine:

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: 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.

Correct Answer: D

Rationale: Vitamin E is an antioxidant commonly found in sources like vegetable oils, nuts, seeds, and green leafy vegetables. It plays a crucial role in protecting cells from damage. Choices A and B are incorrect as Vitamin E is not produced by bacteria in the GI tract nor synthesized by sunlight exposure. Choice C is incorrect as beriberi is a deficiency of Vitamin B1 (thiamine), not Vitamin E.

Correct Answer: D

Rationale: Osmotic pressure is the force that drives water movement across cell membranes due to the presence of electrolytes, helping to balance fluid levels in the body. Choice A, 'energy,' is incorrect as electrolytes do not directly create energy. Choice B, 'active transport,' refers to the movement of molecules across a cell membrane requiring energy, not the movement of water. Choice C, 'passive diffusion,' is the process by which substances move from an area of higher concentration to lower concentration, not related to the movement of water following electrolytes.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.