Correct Answer: B

Rationale: The medulla oblongata is located at the base of the brainstem and is responsible for controlling vital involuntary functions such as breathing, heart rate, and blood pressure. The cerebrum, although the largest part of the brain, is primarily responsible for higher brain functions like thinking and voluntary muscle movements. The cerebellum is involved in coordination, balance, and muscle control. The thalamus acts as a relay station for sensory information but is not directly responsible for regulating involuntary functions like breathing and heart rate. Therefore, the correct answer is the medulla oblongata.

Correct Answer: A

Rationale: The correct answer is A, mediastinum. The mediastinum is the space between the lungs in the chest that contains the heart, major blood vessels, esophagus, trachea, and other structures. This area separates the lungs into right and left cavities. Choice B, pericardial cavity, is incorrect as it refers to the space that surrounds the heart. Choice C, pleural cavity, is not the correct answer as it is the space between the layers of the pleura surrounding each lung. Choice D, thoracic space, is a vague term and not specific to the space between the lungs.

Correct Answer: B

Rationale: The correct answer is B: Gallbladder. The gallbladder is the organ that stores and concentrates bile produced by the liver. Bile is essential for the digestion of fats in the small intestine. The liver produces bile, which is then stored and concentrated in the gallbladder until it is released into the small intestine when needed. Choices A, C, and D are incorrect because the liver produces bile, the pancreas produces digestive enzymes, and the stomach is primarily involved in the digestion of food through acid secretion and mechanical processes, not in storing bile.

Correct Answer: D

Rationale: Type O blood is known as the universal donor because it lacks antigens on the surface of red blood cells. This characteristic makes it compatible with all blood types during transfusions. Type A, Type B, and Type AB blood types have specific antigens that can cause adverse reactions if transfused to an incompatible recipient.

Correct Answer: B

Rationale: Bile emulsifies fats, breaking them down into smaller droplets for easier digestion.