The colonic mucosal cells are very efficient in:

Correct Answer: D

Rationale: The correct answer is D: Absorption of sodium. Colonic mucosal cells are efficient in absorbing sodium through active transport processes. Sodium absorption helps in maintaining fluid and electrolyte balance. Choices A, B, and C are incorrect because primary bile acids are converted into secondary bile acids in the liver, bilirubin is converted into stercobilinogen in the intestines, and aromatic amino acids are mostly absorbed in the small intestine, not the colon.

Correct Answer: C

Rationale: The correct answer is C: both. Occult fecal blood can indicate bleeding anywhere along the gastrointestinal tract. Upper gastrointestinal bleeding typically presents as melena (black, tarry stools), while lower gastrointestinal bleeding can manifest as occult blood in the stool. Therefore, occult fecal blood can be an indication of both upper and lower gastrointestinal bleeding. Choices A and B are incorrect because occult fecal blood is not exclusive to either upper or lower gastrointestinal bleeding alone. Choice D is incorrect since occult fecal blood can indeed be an indication of gastrointestinal bleeding.

Correct Answer: A

Rationale: The correct answer is A: Hemolytic jaundice is caused by more fragile RBCs. When red blood cells are destroyed at an increased rate, it leads to the release of more bilirubin, causing jaundice. Choice B is incorrect because liver damage leads to hepatocellular jaundice, not hemolytic. Choice C is incorrect as hemolytic jaundice is characterized by high bilirubin levels in the blood, not low levels in urine. Choice D is incorrect as option A is the correct explanation for hemolytic jaundice.

Correct Answer: D

Rationale: The correct answer is D because bile pigments, such as bilirubin, increase in the blood in liver disease due to impaired liver function. Bilirubin is a waste product from the breakdown of red blood cells and is normally processed by the liver. Elevated levels of bile pigments in the blood are a common indicator of liver dysfunction. Choice A is incorrect because bile pigments are derived from heme, not the globin portion of hemoglobin. Choice B is incorrect because bile pigments aid in the emulsification of fats but do not directly help in fat digestion and absorption. Choice C is incorrect as bile pigments are conjugated with glucuronic acid, not sulphate, in the liver.

Correct Answer: B

Rationale: The correct answer is B: Stomach and Duodenum. Submucosal glands are found in the submucosa of the stomach and duodenum. In the stomach, these glands secrete mucus and bicarbonate to protect the lining from stomach acid. In the duodenum, they secrete mucus to protect the lining from the acidic chyme entering from the stomach. Choices A, C, and D are incorrect because submucosal glands are not typically found in the oesophagus or ileum. The rationale for the correct answer is based on the anatomical location and function of submucosal glands in the gastrointestinal tract.