Which of the following minerals is important for bone health and is stored in bones by the skeletal system?

Correct Answer: C

Rationale: The correct answer is Calcium (Choice C). Calcium is essential for bone health and is stored in bones by the skeletal system. Bones act as a reservoir for calcium, playing a critical role in maintaining bone strength and density. Iron, sodium, and magnesium are important for various bodily functions but are not primarily stored in bones for bone health. Iron is crucial for oxygen transport, sodium helps regulate fluid balance, and magnesium is involved in over 300 enzymatic reactions in the body.

Correct Answer: B

Rationale: Smooth muscle is the correct answer. It is found in the walls of blood vessels and helps regulate blood flow by contracting and relaxing to adjust the diameter of the vessels. Skeletal muscle, found attached to bones, is responsible for voluntary movements and is not typically found in blood vessel walls. Cardiac muscle is specific to the heart and responsible for pumping blood, not found in blood vessel walls. Striated muscle, another term for skeletal muscle, is characterized by its striped appearance under a microscope but is not present in blood vessel walls.

Correct Answer: C

Rationale: The nervous system is responsible for detecting touch (option A), regulating body temperature (option B), and controlling muscle movement (option D). Producing insulin (option C) is a function of the endocrine system, which produces hormones like insulin to regulate metabolism and glucose levels. Therefore, option C is the correct answer as it is not a function of the nervous system.

Correct Answer: B

Rationale: The correct answer is B: Decreased heart rate and body temperature. A malfunctioning thyroid gland that produces abnormally low levels of thyroid hormones leads to hypothyroidism, resulting in decreased metabolic activity. This reduction in metabolic rate can cause a decreased heart rate and lower body temperature. Choices A, C, and D are incorrect because hypothyroidism typically manifests as symptoms such as fatigue, weight gain, cold intolerance, bradycardia, and decreased body temperature, rather than increased energy levels, enhanced muscle growth, faster metabolism, or heightened alertness.

Correct Answer: C

Rationale: Sarcomeres are the smallest contractile units within muscle cells. They consist of overlapping filaments of actin and myosin proteins, which interact to produce muscle contractions. Myocytes are the entire muscle cells, myofibrils are bundles of protein filaments found within muscle cells, and tendons are tough connective tissues that connect muscles to bones. Therefore, sarcomeres specifically represent the contractile units responsible for muscle contraction, making them the correct answer in this context.