Which part of the digestive system is responsible for the absorption of water and electrolytes?

Correct Answer: B

Rationale: The correct answer is B: Large intestine. The large intestine is responsible for the absorption of water and electrolytes from the remaining indigestible food matter that passes through the small intestine. It reabsorbs water and electrolytes to maintain the body's fluid balance. The small intestine primarily absorbs nutrients and vitamins, while the stomach is responsible for the initial digestion of food and the pancreas secretes digestive enzymes into the small intestine. Therefore, the large intestine is the correct choice for water and electrolyte absorption in the digestive system.

Correct Answer: B

Rationale: The correct answer is B because the submandibular salivary gland is responsible for producing around 70-75% of total saliva, including amylase. If it stops functioning, there would be a severe deficiency of amylase, leading to impaired digestion of starches. Choice A is incorrect because the reduction in salivary secretion would be more significant than 20%. Choice D is incorrect as mucins are produced by other salivary glands and not solely by the submandibular gland.

Correct Answer: D

Rationale: The correct answer is D because pro-carboxypeptidase is an inactive form of carboxypeptidase, which is involved in breaking down proteins. It is not a mismatch. A is correct as proteolytic enzymes indeed break down proteins. B is correct as amylase breaks down carbohydrates. C is correct as nuclease enzymes break down nucleic acids. Therefore, the mismatch is only seen in option D.

Correct Answer: A

Rationale: The correct answer is A: anemia. Carcinoma of the cecum or right colon often presents with chronic blood loss, leading to iron deficiency anemia. This is due to the longer transit time in the right colon allowing for more time for blood to be lost and for the iron in the blood to be absorbed. Choices B, C, and D are less characteristic of carcinoma of the cecum or right colon. Polyposis is more commonly associated with familial adenomatous polyposis, bowel obstruction is more common in advanced stages regardless of location, and diarrhea is more commonly seen in rectal carcinomas due to irritation of the rectal mucosa.

Correct Answer: C

Rationale: Rationale for Correct Answer C: Obstructive jaundice is caused by blockage in the bile ducts, leading to decreased excretion of bilirubin into the intestine. This results in dark stool due to excess stercobilin, a byproduct of bilirubin breakdown. Other choices are incorrect because: A: Fragile red blood cells cause hemolytic jaundice, not obstructive jaundice. B: Elevated blood hemobilirubin is seen in hemolytic jaundice, not obstructive jaundice. D: Dark brown urine is associated with conditions like hemoglobinuria, not obstructive jaundice.