Which of the following vitamins is not stored in the liver?

Correct Answer: A

Rationale: The correct answer is A: Vitamin C. Vitamin C is water-soluble and not stored in the liver. It gets absorbed in the intestines and any excess is excreted in the urine. Vitamin D (choice B) is fat-soluble and stored in the liver. Vitamin B12 (choice C) is also stored in the liver. Vitamin A (choice D) is fat-soluble and stored in the liver as well. Thus, the correct answer is A as it is the only water-soluble vitamin among the options.

Correct Answer: B

Rationale: The correct answer is B: large intestine. The small intestine, plicae circulares, and crypts of Lieberkuhn are all structures found in the small intestine, involved in absorption and digestion. The large intestine is a separate part of the digestive system primarily responsible for water absorption and waste elimination. Therefore, it does not belong with the other choices related to the small intestine.

Correct Answer: B

Rationale: The correct answer is B (stomach) because amylase is an enzyme that breaks down carbohydrates, and it is primarily found in the mouth and the small intestine (duodenum and pancreas). In the mouth, salivary amylase begins the digestion of starches. In the small intestine, pancreatic amylase continues this process. The stomach, however, is not a site for amylase secretion but rather secretes pepsin for protein digestion. Therefore, amylase is not found in the stomach. Choices A, C, and D are incorrect because amylase is indeed present in the mouth, duodenum, and pancreas, respectively.

Correct Answer: B

Rationale: The correct answer is B because pancreatic juice contains enzymes such as Trypsinogen, Lipase, Amylase, and Procarboxypeptidase. Trypsinogen helps in protein digestion, Lipase breaks down fats, Amylase digests carbohydrates, and Procarboxypeptidase aids in protein digestion. Choice A is incorrect because it includes Rennin, which is not typically found in pancreatic juice. Choice C is incorrect because Pepsin is a stomach enzyme, not found in pancreatic juice. Choice D is incorrect because Maltase is an enzyme found in the small intestine, not in pancreatic juice.

Correct Answer: C

Rationale: The correct answer is C: facilitated transport. Fructose is absorbed through facilitated diffusion using specific carrier proteins in the intestinal mucosa. This process does not require energy input and allows fructose to move down its concentration gradient. Unlike active transport (requiring energy) and co-transport mechanisms (involving multiple substances), fructose absorption occurs through facilitated transport by specific carrier proteins. Simple diffusion is not the main mechanism for fructose absorption due to its hydrophilic nature. Thus, facilitated transport best describes how fructose is absorbed by the intestinal mucosa.