Identify functions of calcium within the body.

Correct Answer: D

Rationale: The correct answer is D because calcium plays essential roles in clotting, bone health, nerve conduction, and muscle contraction. Calcium is crucial for the coagulation cascade in clotting, is a key component of bone mineralization, is required for neurotransmitter release in nerve conduction, and is involved in muscle contraction by regulating the interactions between actin and myosin. Choices A, B, and C are incorrect individually because they only represent some of the functions of calcium, whereas choice D encompasses all the vital functions of calcium in the body.

Correct Answer: D

Rationale: The correct answer is D because endocrine glands are ductless and release hormones directly into the bloodstream, while exocrine glands release their secretions into ducts or onto the surface of the body. This key difference in how they release their products is essential in distinguishing between endocrine and exocrine glands. A: Endocrine glands release hormones, not waste products. B: The interconnection of glands is not a defining characteristic to differentiate between endocrine and exocrine glands. C: Endocrine glands are not exclusively formed by epithelial tissue, and exocrine glands are not solely connective tissues.

Correct Answer: B

Rationale: The correct answer is B: Pineal gland. The pineal gland secretes melatonin, a hormone that regulates the body's sleep-wake cycle, thus contributing to setting the body's biological clock. This gland responds to light and darkness, helping to synchronize our internal clock with the day-night cycle. The pituitary gland (A) regulates various hormones but not specifically the biological clock. The thymus gland (C) is responsible for immune function, not the biological clock. The adrenal gland (D) secretes hormones related to stress response, not the biological clock. In summary, the pineal gland is key in regulating the body's biological clock through melatonin secretion, making it the correct choice.

Correct Answer: B

Rationale: The correct answer is B because a congenital defect in gastric lipase would not lead to steatorrhoea. Gastrinoma, ileal disease with failure to reabsorb bile salts, and exocrine pancreatic disease can all cause steatorrhoea due to impaired fat digestion or absorption. Gastrinoma can lead to excessive acid production, which can interfere with fat digestion. Ileal disease can affect the reabsorption of bile salts necessary for fat digestion. Exocrine pancreatic disease can result in insufficient pancreatic enzymes needed for fat digestion. Therefore, choice B is the exception as it does not directly impact fat digestion or absorption.

Correct Answer: C

Rationale: Rationale for Correct Answer C: Oligosaccharidase deficiency leads to osmotic diarrhea because the incomplete breakdown of oligosaccharides in the small intestine results in unabsorbed sugars attracting water, causing diarrhea. This is a direct consequence of the deficiency in enzymes responsible for breaking down oligosaccharides. This is why Choice C is correct. Summary of Incorrect Choices: A: Salivary amylase works best at a neutral pH of around 6.7, not alkaline pH. B: Lactose intolerance is due to a deficiency in lactase enzyme, not related to carbohydrate digestion in the small intestine. D: Salivary amylase is inactivated in the acidic environment of the stomach, so it does not continue to digest carbohydrates there.