Which is absorbed mainly in the colon?

Correct Answer: A

Rationale: The correct answer is A: short chain fatty acids. The colon is where most of the absorption of short chain fatty acids occurs after digestion in the small intestine. Short chain fatty acids are produced by gut bacteria breaking down dietary fiber and play a crucial role in energy production and maintaining gut health. Calcium is primarily absorbed in the small intestine, vitamin K is absorbed in the small intestine and liver, and oligosaccharides are mainly broken down in the small intestine by enzymes. Therefore, A is the correct answer as it aligns with the specific absorption function of the colon.

Correct Answer: D

Rationale: The correct answer is D because in hemolytic anemia, there is an increased breakdown of red blood cells, leading to excess bilirubin production. This results in unconjugated hyperbilirubinemia. Unconjugated bilirubin is less soluble than conjugated bilirubin (Choice A). Conjugated bilirubin is excreted via the bile into the intestine, but not all of it is excreted in this manner (Choice B). Bile duct obstruction typically leads to conjugated hyperbilirubinemia, not unconjugated (Choice C).

Correct Answer: D

Rationale: The correct answer is D: the standard unit of heat energy necessary to raise the temperature of 1gm of water 1° from 15-16°C. This is because a calorie is defined as the amount of heat energy required to raise the temperature of 1 gram of water by 1 degree Celsius. This definition aligns perfectly with choice D. Choices A, B, and C are incorrect because they involve raising the temperature of different substances (1L of water, 1gm of mercury, and 1gm of water) by 1 degree Celsius over different temperature ranges (15-16°C, 17-18°C), which do not match the standard definition of a calorie.

Correct Answer: D

Rationale: The correct answer is D because calcium regulation in the blood is primarily controlled by hormones released from the parathyroid and thyroid glands. Parathyroid hormone (PTH) released by the parathyroid glands increases blood calcium levels, while calcitonin released by the thyroid gland decreases blood calcium levels. The other choices are incorrect because the testes primarily produce hormones related to reproduction (not calcium regulation), the adrenal medulla and pancreas are not directly involved in calcium regulation, and the thymus is involved in immune function but not in calcium regulation.

Correct Answer: B

Rationale: The correct answer is B: oxytocin. Oxytocin is the hormone responsible for stimulating the contraction of smooth muscle in the uterus during childbirth and labor. It acts on the smooth muscle cells in the uterine wall, causing them to contract and aiding in the process of childbirth. A: Follicle-stimulating hormone is involved in the regulation of the reproductive system, particularly in the development of ovarian follicles. C: Prolactin is primarily responsible for milk production in the mammary glands. D: Luteinizing hormone triggers ovulation and the formation of the corpus luteum in the ovary. Therefore, the correct answer is B because it directly affects the contraction of smooth muscle in the uterus, which is essential during childbirth.