Cholecystokinin (CCK):

Correct Answer: C

Rationale: The correct answer is C because Cholecystokinin (CCK) is a hormone secreted by the duodenum in response to the presence of fats and proteins. It stimulates the pancreatic acini to secrete digestive enzymes such as lipase and proteases. This helps in the digestion and absorption of fats and proteins. The other choices are incorrect because A is false - CCK is secreted by the duodenum, not the gastric antrum. B is false - CCK is actually stimulated by the presence of fats in the duodenum. D is false - CCK actually stimulates gallbladder contraction to release bile, aiding in fat digestion.

Correct Answer: C

Rationale: The majority of nutrient absorption occurs in the small intestine. Here's the rationale: 1. The small intestine is where most digestion and absorption of nutrients occur due to its large surface area. 2. Villi and microvilli in the small intestine increase the absorption surface for nutrients like carbohydrates, proteins, and fats. 3. Specific enzymes and bile are secreted in the small intestine to aid in the breakdown and absorption of nutrients. 4. The large intestine primarily absorbs water and electrolytes, not nutrients. In summary, the mouth is mainly for mechanical digestion, the stomach primarily digests food, and the large intestine absorbs water, making the small intestine the correct choice for nutrient absorption.

Correct Answer: B

Rationale: The correct answer is B: Liver. The liver produces bile, which is a greenish-yellow fluid that helps in the digestion and absorption of fats. It is stored in the gallbladder and released into the small intestine when needed. The stomach (A) produces gastric juices, not bile. The pancreas (C) produces digestive enzymes, but not bile. The small intestine (D) is where bile is released to aid in the digestion of fats, not where it is produced or stored.

Correct Answer: B

Rationale: The correct answer is B: liver. The liver is not part of the gastrointestinal tract. The GI tract consists of the esophagus, stomach, and small intestine, where digestion and absorption of nutrients occur. The liver is an accessory organ that aids in digestion by producing bile but is not part of the tract itself. The liver is involved in detoxification, storage of nutrients, and production of important proteins, but it does not play a direct role in the digestion process. Therefore, the liver is the correct answer.

Correct Answer: B

Rationale: The correct answer is B because a waist circumference of 42 inches in men signifies abdominal obesity, which is a significant risk factor for health issues related to obesity. A high waist circumference indicates excess visceral fat, which is linked to heart disease and other health problems. Choice A is incorrect because a BMI of 18 kg/m2 indicates underweight, not obesity. Choice C is incorrect because a BMI of 24 kg/m2 falls within the healthy weight range, not indicating obesity. Choice D is incorrect because a waist circumference of 34 inches in women is considered normal, not indicative of obesity.