Which of these is a feature of the large intestine?

Correct Answer: B

Rationale: The correct answer is B: haustra. The large intestine has haustra, which are pouches formed by muscle contractions that help in moving feces along the colon. Villi (choice A) and microvilli (choice C) are features of the small intestine, aiding in nutrient absorption. Lacteals (choice D) are lymphatic vessels in the small intestine. Therefore, the presence of haustra is a distinct feature of the large intestine, making it the correct choice in this context.

Correct Answer: B

Rationale: The correct answer is B: amylase. Amylase is responsible for breaking down carbohydrates into smaller sugar molecules in the digestive system. It is produced in the saliva and pancreas. Lipase (A) digests fats, pepsin (C) digests proteins, and trypsin (D) also digests proteins, not carbohydrates. Therefore, amylase is the correct enzyme for carbohydrate digestion.

Correct Answer: D

Rationale: Saliva does not contain platelets because platelets are components of blood responsible for blood clotting, not found in saliva. Saliva does contain ABO blood group antigens, lysozymes for antibacterial activity, and immunoglobulins for immune function. Platelets are not a normal component of saliva, making option D the correct answer.

Correct Answer: A

Rationale: After a cholecystectomy, the gallbladder is removed, affecting bile storage and release. The liver still produces bile, but it is not stored in the gallbladder for efficient release when needed. This results in inadequate bile availability to emulsify fats, leading to difficulty digesting fat-rich foods. Choices B and C are incorrect as they do not directly address the issue of insufficient bile production. Choice D is incorrect as bile concentration is not the primary concern post-cholecystectomy.

Correct Answer: D

Rationale: The correct answer is D because the oesophageal phase of swallowing starts when a bolus enters the oropharynx. This triggers the swallowing reflex, leading to the contraction of the upper oesophageal sphincter and relaxation of the lower sphincter to allow the bolus to move into the oesophagus. Choices A and B are incorrect because the oesophageal phase can proceed with the mouth open and is not primarily reflex-controlled by the myenteric plexus. Choice C is incorrect as the swallowing center in the brain coordinates and initiates the swallowing reflex but is not the primary control of the oesophageal phase.