Which vitamin is essential for the absorption of calcium?

Correct Answer: B

Rationale: Vitamin D is crucial for the absorption of calcium in the intestines, which is vital for maintaining strong bones and teeth. It helps regulate calcium levels in the blood and promotes bone mineralization, making it an essential vitamin for overall bone health. Vitamin A (Choice A) is important for vision and immune function, not specifically for calcium absorption. Vitamin K (Choice C) is essential for blood clotting, while Vitamin C (Choice D) is known for its role in collagen production and antioxidant properties, but not directly related to calcium absorption.

Correct Answer: A

Rationale: The correct answer is the hypothalamus. This brain structure plays a crucial role in regulating hunger, thirst, body temperature, and various autonomic functions. The hypothalamus is responsible for maintaining homeostasis by responding to sensory signals and releasing appropriate hormones to control these essential physiological processes. The cerebellum (Choice B) is primarily involved in coordinating movement and balance, not hunger and thirst. The medulla oblongata (Choice C) is responsible for regulating vital autonomic functions such as breathing and heartbeat, but not hunger and thirst. The cerebrum (Choice D) is involved in higher brain functions such as thinking, decision-making, and processing sensory information, but it is not primarily responsible for regulating hunger and thirst.

Correct Answer: D

Rationale: The hypothalamus is the part of the brain responsible for regulating body temperature, along with controlling other autonomic functions like hunger, thirst, and sleep. It acts as the body's internal thermostat, helping to maintain a stable internal environment despite external temperature changes. The cerebrum is mainly associated with functions like thinking, perception, and voluntary movements, making it unrelated to regulating body temperature. The cerebellum is involved in coordination and balance, not in regulating body temperature. The brainstem is essential for basic life functions like breathing and heart rate, but it is not primarily responsible for regulating body temperature.

Correct Answer: C

Rationale: Smooth muscle tissue is found in the walls of hollow organs, such as the intestines, blood vessels, and bladder. It contracts involuntarily, allowing for movements like peristalsis in the intestines and regulation of blood flow in blood vessels. Skeletal muscle (Choice A) is attached to bones and helps in voluntary movements. Cardiac muscle (Choice B) is found in the heart and contracts involuntarily to pump blood. Striated muscle (Choice D) refers to both skeletal and cardiac muscles, which have a striped appearance due to the organization of their filaments. However, smooth muscle (Choice C) is specifically the type found in hollow organs.

Correct Answer: A

Rationale: Insulin, produced by the pancreas, is the hormone responsible for regulating blood sugar levels. It works by facilitating the uptake of glucose into cells, helping to lower blood sugar levels. Glucagon, on the other hand, works to increase blood sugar levels by promoting the release of glucose from the liver. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism. Melatonin, a hormone that helps regulate sleep-wake cycles, is not responsible for regulating blood sugar levels. Therefore, the correct answer is insulin.

Correct Answer: B

Rationale: Vitamin D is crucial for the absorption of calcium in the intestines, which is vital for maintaining strong bones and teeth. It helps regulate calcium levels in the blood and promotes bone mineralization, making it an essential vitamin for overall bone health. Vitamin A (Choice A) is important for vision and immune function, not specifically for calcium absorption. Vitamin K (Choice C) is essential for blood clotting, while Vitamin C (Choice D) is known for its role in collagen production and antioxidant properties, but not directly related to calcium absorption.

Correct Answer: B

Rationale: The correct term for red blood cell production is erythropoiesis. This process specifically refers to the production of red blood cells, mainly occurring in the bone marrow. Hematopoiesis is a broader term that encompasses the production of all blood cells, including red blood cells, white blood cells, and platelets. Phagocytosis is the process of engulfing and digesting particles by cells like macrophages, not related to red blood cell production. Thrombopoiesis is the production of platelets, not red blood cells.

Correct Answer: C

Rationale: Vitamin D is the correct answer. It is essential for immune system function as it helps regulate and support the immune response. Vitamin D plays a crucial role in calcium absorption, which is necessary for maintaining strong and healthy bones. Vitamin A is important for vision and skin health, not specifically immune function. Vitamin C is known for its antioxidant properties and its role in collagen production, not primarily for immune system function. Vitamin K is essential for blood clotting and bone health, but it is not directly related to immune system function.

Correct Answer: A

Rationale: Vitamin A is the correct answer. It is crucial for maintaining healthy skin as it supports skin cell growth, repair, and overall skin health. Additionally, vitamin A plays a role in vision and immune function. Deficiency in vitamin A can lead to skin issues such as dryness and poor wound healing. Vitamin C is known for its role in collagen synthesis and antioxidant properties, while Vitamin D is important for bone health and immunity. Vitamin K is essential for blood clotting, but it is not primarily associated with skin health.