Which hormone is responsible for the regulation of calcium levels in the blood?

Correct Answer: B

Rationale: Parathyroid hormone, produced by the parathyroid glands, is responsible for regulating calcium levels in the blood. It achieves this by increasing calcium absorption in the intestines and kidneys, thus maintaining appropriate calcium levels in the bloodstream. Insulin is involved in glucose metabolism, not calcium regulation. Cortisol is a stress hormone that affects various body functions but not calcium levels. Melatonin is responsible for regulating the sleep-wake cycle, not calcium levels.

Correct Answer: B

Rationale: The gallbladder's main function is to store and concentrate bile produced by the liver. Bile is essential for the digestion and absorption of fats in the small intestine. Therefore, the correct answer is B, as the gallbladder acts as a reservoir for bile rather than producing it. Choices A, C, and D are incorrect because the gallbladder does not produce bile, detoxify harmful substances, or regulate blood sugar in the digestive system.

Correct Answer: B

Rationale: Tendons are the correct answer. They are strong connective tissues that connect muscles to bones, allowing movement when muscles contract. Ligaments connect bones to other bones, providing joint stability. Cartilage is a firm, flexible connective tissue present in joints and the outer ear. Fascia is a connective tissue that surrounds muscles, blood vessels, and nerves, offering support and protection. Therefore, the correct tissue type that connects muscles to bones is tendons.

Correct Answer: B

Rationale: Vitamin B12 is the correct answer. It is crucial for the formation and maturation of red blood cells, playing a vital role in preventing megaloblastic anemia. Additionally, Vitamin B12 is essential for maintaining nerve function. Vitamin A is important for vision and immune function, Vitamin C is necessary for collagen synthesis and immune health, and Vitamin D is crucial for bone health and immune function. Therefore, options A, C, and D are incorrect as they do not play a direct role in the formation of red blood cells.

Correct Answer: C

Rationale: The correct answer is the thyroid gland (Choice C). The thyroid gland plays a crucial role in regulating metabolism by producing hormones like thyroxine, which control the body's metabolic rate. It also helps in controlling calcium levels in the blood through the release of calcitonin. The pituitary gland (Choice A) is known as the 'master gland' as it controls other glands but is not primarily responsible for regulating metabolism and calcium levels. The adrenal gland (Choice B) produces hormones like cortisol and adrenaline, which are involved in the stress response and metabolism, but they do not specifically regulate calcium levels. The pineal gland (Choice D) mainly produces melatonin, a hormone that helps in regulating sleep-wake cycles and has no direct role in metabolism or calcium level regulation.

Correct Answer: B

Rationale: The correct answer is B: Support and protection. The primary functions of the skeletal system include providing structural support to the body and protecting internal organs. While the skeletal system also plays a role in hematopoiesis (production of blood cells) and stores minerals, its main function is to support the body's framework and protect vital organs. Choices A, C, and D are incorrect as they do not directly relate to the primary functions of the skeletal system.

Correct Answer: B

Rationale: Adrenaline, also known as epinephrine, is released during the body's fight-or-flight response. This hormone prepares the body for rapid action by increasing heart rate, dilating airways, and redirecting blood flow to essential organs in response to stress or danger. Insulin is not released during the fight-or-flight response; its primary role is to regulate blood sugar levels. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, and cortisol is released in response to stress to regulate various bodily functions, but adrenaline is the hormone specifically associated with the fight-or-flight response.

Correct Answer: B

Rationale: The correct answer is B: To produce bile. The liver's primary function in the digestive system is to produce bile. Bile is essential for the digestion and absorption of fats in the small intestine. It helps emulsify fats, making it easier for enzymes to break them down into smaller molecules for absorption. Choices A, C, and D are incorrect as storing glucose is primarily done in the liver for energy maintenance, detoxifying harmful substances is a function of the liver related to metabolism but not specifically in the digestive system, and absorbing nutrients is mainly done in the small intestine rather than the liver.

Correct Answer: B

Rationale: The correct answer is a hinge joint. The elbow joint is a hinge joint that allows for flexion and extension movements, much like the movement of a door hinge. This type of joint permits movement in one plane, similar to the action of opening and closing a door. The other choices are incorrect: A) Ball and socket joints allow for a wide range of motion in multiple directions, such as the hip and shoulder joints. C) Pivot joints allow rotation around a single axis, like the joint at the top of the neck that allows the head to turn from side to side. D) Saddle joints are found in the thumb and have a biaxial range of motion allowing flexion, extension, adduction, abduction, and circumduction.