Low-density lipoprotein (LDL) is:

Correct Answer: A

Rationale: The correct answer is A because LDL is a lipoprotein that contains high amounts of cholesterol and is associated with increased risk of atherosclerosis and coronary artery disease. LDL is often referred to as beta-lipoprotein due to its density. Choice B is incorrect as it describes HDL, which contains small amounts of cholesterol and triglycerides, and is associated with a decreased risk of heart disease. It is also known as alpha-lipoprotein. Choice C is incorrect as it describes VLDL (very low-density lipoprotein), which carries most cholesterol from the liver to the tissues due to its large proportion of lipids to proteins. Choice D is incorrect as it describes chylomicrons, which are large lipoprotein particles created by the absorptive cells of the small intestine. They transport lipids to adipose tissue for breakdown by lipoprotein lipase.

Correct Answer: B

Rationale: The correct answer is B: Defective bone mineralization. Etidronate is a bisphosphonate used to treat osteoporosis by inhibiting bone resorption, leading to increased bone density. However, long-term use can result in defective bone mineralization, leading to brittle or weakened bones. A: Anorexia is not a known side effect of etidronate and is more commonly associated with other medications or medical conditions. C: Hypercalcemia is unlikely with etidronate use since it works to reduce calcium loss from bones. D: Cardiac arrhythmias are not a typical side effect of etidronate and are more commonly associated with other medications or underlying heart conditions.

Correct Answer: C

Rationale: The correct answer is C because ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that can reduce the antihypertensive effect of diuretics like chlorthalidone. Ibuprofen can lead to sodium and water retention, counteracting the diuretic's effects. Choices A, B, and D are true statements. A is true because furosemide can cause hypokalemia, increasing the risk of digitalis toxicity. B is true as chlorthalidone can decrease lithium excretion, potentially leading to lithium toxicity. D is true because chlorthalidone has a longer duration of action compared to furosemide due to its longer half-life.

Correct Answer: D

Rationale: The correct answer is D because Chloramphenicol is a broad-spectrum antibiotic that inhibits protein synthesis in bacteria, making it bacteriostatic. It affects both Gram-positive and Gram-negative microorganisms. Choice A is incorrect because chloramphenicol is bacteriostatic, not bactericidal. Choice B is incorrect because it influences both Gram-positive and Gram-negative bacteria. Choice C is incorrect because it also influences both types of bacteria and it is bacteriostatic, not bactericidal.

Correct Answer: D

Rationale: The correct answer is D because fluoroquinolones are broad-spectrum antibiotics effective against a variety of Gram-negative and Gram-positive microorganisms, including Mycoplasmas and Chlamydiae. Fluoroquinolones work by targeting bacterial DNA gyrase and topoisomerase IV, which are essential for DNA replication. This mechanism of action allows fluoroquinolones to inhibit the growth of a wide range of bacteria. Choices A, B, and C are incorrect because fluoroquinolones are not limited to only Gram-negative or Gram-positive microorganisms, but rather have activity against both types of bacteria, making them effective against a diverse range of pathogens.