Which vitamin is essential for the maintenance of healthy skin?

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.

Correct Answer: B

Rationale: Erythropoietin is the correct answer. It is the hormone responsible for stimulating the production of red blood cells. Erythropoietin is produced by the kidneys in response to low oxygen levels in the blood. This hormone promotes the generation of more red blood cells to increase the blood's oxygen-carrying capacity. Insulin (Choice A), Glucagon (Choice C), and Thyroxine (Choice D) do not stimulate the production of red blood cells. Insulin regulates blood sugar levels, Glucagon increases blood sugar levels, and Thyroxine regulates metabolism.

Correct Answer: B

Rationale: The correct answer is B, Cortisol. Cortisol is the hormone produced by the adrenal cortex. It plays a crucial role in regulating metabolism, immune response, and managing stress. Insulin is produced by the pancreas, thyroxine by the thyroid gland, and glucagon by the pancreas. Therefore, choices A, C, and D are incorrect as they are not hormones produced by the adrenal cortex.

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: Vitamin D is crucial for the absorption of calcium in the intestines. It aids in maintaining optimal calcium levels in the body, promoting strong bones and teeth. Without sufficient Vitamin D, the absorption of calcium can be compromised, leading to potential issues with bone health. Choices A, C, and D are incorrect. Vitamin A is essential for vision, skin health, and immune function. Vitamin K is necessary for blood clotting and bone metabolism. Vitamin C is important for collagen synthesis, wound healing, and immune function, but it is not directly involved in calcium absorption.

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: 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: The pinna, also known as the auricle, is the external part of the ear that is most visible. It helps in collecting sound waves and directing them into the ear canal for further processing by the ear structures. The pinna's visible location makes it easily identifiable as the prominent external feature of the ear. Choices B, C, and D are incorrect. The Organ of Corti is located within the cochlea and is responsible for converting sound vibrations into electrical signals. The cochlea is a spiral-shaped, fluid-filled structure in the inner ear that plays a crucial role in hearing. The ear canal is a passage that leads to the eardrum and is not the most visible part of the ear.

Correct Answer: A

Rationale: The primary function of the respiratory system is to facilitate the exchange of oxygen and carbon dioxide between the air and the bloodstream. Oxygen is taken in during inhalation and transported to cells, while carbon dioxide is removed during exhalation as a waste product of cellular metabolism. Choices B, C, and D are incorrect as they do not reflect the primary function of the respiratory system. Regulating body temperature is mainly controlled by the thermoregulatory system, fighting infections is a function of the immune system, and producing energy is primarily done by the metabolic system.