Where does most nutrient digestion and absorption occur?

Correct Answer: B

Rationale: The small intestine is the correct answer. It is the primary site for nutrient digestion and absorption in the digestive system. The small intestine plays a crucial role in breaking down carbohydrates, proteins, and fats into forms that can be absorbed by the body. While the large intestine absorbs water and electrolytes, the majority of nutrient absorption occurs in the small intestine. The stomach primarily functions in the initial digestion of proteins, and the mouth begins the mechanical breakdown of food through chewing.

Correct Answer: A

Rationale: The correct answer is A. Pancreatic amylases break down starch into disaccharides in the small intestine. This process occurs in the small intestine, not the large intestine or pancreas. Brush border enzymes act on disaccharides to break them down into monosaccharides, while luminal enzymes are not specifically involved in the conversion of starch to disaccharides.

Correct Answer: B

Rationale: The correct answer is B. Viscous (soluble) fiber binds with bile acids in the intestine, which are then excreted. The liver must use cholesterol to make more bile acids, thereby lowering blood cholesterol levels. Choice A is incorrect as insoluble fiber does not bind with cholesterol in the large intestine. Choice C is incorrect as soluble fiber does not directly bind with cholesterol in the blood. Choice D is incorrect as insoluble fiber does not convert to bile in the large intestine to bind with cholesterol.

Correct Answer: A

Rationale: Vitamin K is synthesized by bacteria in the gastrointestinal tract. Choice B is incorrect as the synthesis of Vitamin D, not K, can be induced by sunlight exposure. Choice C is incorrect as beriberi is a condition caused by thiamine (Vitamin B1) deficiency, not Vitamin K. Choice D is incorrect as Vitamin E is commonly found in vegetable oils, not Vitamin K.

Correct Answer: B

Rationale: The correct answer is B: vitamin D and vitamin B12. Vegans may need to supplement vitamin D and B12 as these nutrients are mainly found in animal products. While choices A, C, and D are essential vitamins, they are not typically lacking in a vegan diet. Vitamin C can be obtained from various plant sources, vitamin A can be derived from beta-carotene in plants, and vitamin E and K are also found in plant-based foods. Niacin, although important, can be sourced from plant-based sources and is not a common deficiency in vegan diets.