Which of the following hormones is responsible for regulating metabolism?

Correct Answer: B

Rationale: Thyroxine, produced by the thyroid gland, is the hormone responsible for regulating metabolism. It plays a fundamental role in controlling the body's metabolic rate, affecting processes such as energy production and utilization. Thyroxine also influences growth and development in the body. Choice A, Insulin, is involved in regulating blood sugar levels and promoting the storage of glucose. While insulin has an impact on metabolism, it is not primarily responsible for regulating overall metabolic rate. Choice C, Glucagon, acts in opposition to insulin, stimulating the release of glucose from the liver to increase blood sugar levels. Glucagon primarily targets glucose regulation rather than overall metabolism. Choice D, Cortisol, is known as the stress hormone and plays a role in the body's response to stress, regulation of blood pressure, immune function, and anti-inflammatory actions. While cortisol can have some effects on metabolism during stress responses, it is not the primary hormone responsible for regulating overall metabolic rate.

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: A

Rationale: The biceps brachii muscle is the primary muscle responsible for flexing the forearm at the elbow joint. When the biceps brachii contracts, it causes the forearm to move towards the upper arm, resulting in flexion at the elbow. In contrast, the triceps brachii is responsible for extending the forearm, the deltoid muscle is primarily involved in shoulder movements, and the brachialis muscle also aids in flexion of the forearm but to a lesser extent compared to the biceps brachii.

Correct Answer: B

Rationale: The correct answer is a ball and socket joint like the shoulder or hip joint, as it allows for movement in multiple directions, including rotation. This type of joint offers a high degree of mobility due to its structure, where the rounded end of one bone fits into the cup-like socket of another bone. A hinge joint (Choice A) allows movement primarily in one plane, like the elbow or knee. A pivot joint (Choice C) allows for rotation around an axis, seen in the neck joint. A saddle joint (Choice D) enables movements in multiple directions but to a lesser extent compared to a ball and socket joint, found in the thumb joint.

Correct Answer: B

Rationale: The skin is the largest organ in the human body. It serves as a protective barrier against the environment, regulates temperature, and provides sensory information. The liver, brain, and heart are vital organs, but they are not as extensive as the skin. The liver is primarily responsible for detoxification and metabolism. The brain is the control center of the body, coordinating various functions. The heart is a crucial organ that pumps blood throughout the body. However, in terms of size, the skin surpasses all of these organs.