Which part of the brain is responsible for regulating body temperature?

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: B

Rationale: Vitamin C is essential for the synthesis of collagen, a crucial protein that plays a significant role in maintaining the structural integrity of skin, blood vessels, and bones. Collagen is responsible for the strength, elasticity, and firmness of these tissues. Without sufficient vitamin C, the body cannot form collagen properly, leading to various health issues like scurvy, impaired wound healing, and fragile blood vessels. Choices A, C, and D are incorrect. Vitamin A plays a role in vision, immune function, and skin health. Vitamin D is crucial for bone health and immune function, while Vitamin E is an antioxidant that helps protect cells from damage.

Correct Answer: B

Rationale: Cardiac muscle tissue, represented by choice B, is the correct answer. Cardiac muscle tissue is unique to the heart and responsible for its involuntary contractions that pump blood throughout the body. Smooth muscle (choice A) is found in the walls of hollow organs, skeletal muscle (choice C) is attached to bones for movement, and striated muscle (choice D) is a general term that can refer to both cardiac and skeletal muscle but is not specific to the heart.

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: A

Rationale: Oxytocin is the correct answer. It is released by the posterior pituitary gland and plays a vital role in childbirth and lactation. Oxytocin promotes uterine contractions during labor and milk ejection during breastfeeding. Choice B, Thyroxine, is incorrect as it is produced by the thyroid gland. Choice C, Insulin, is incorrect as it is produced by the pancreas. Choice D, ADH (Antidiuretic Hormone), is also released by the posterior pituitary gland, but it is not the hormone primarily associated with childbirth and lactation.

Correct Answer: A

Rationale: Melatonin, produced by the pineal gland, regulates the sleep-wake cycle by responding to light and darkness in the environment. It plays a crucial role in signaling the body when it's time to sleep and wake up, helping to establish and maintain a healthy circadian rhythm. Thyroxine, Insulin, and Cortisol do not directly regulate the sleep-wake cycle, making them incorrect choices for this question.

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: The thyroid gland is responsible for regulating metabolism. It produces hormones such as thyroxine, which plays a key role in influencing the body's metabolic rate. The pituitary gland is known as the 'master gland' but is not directly responsible for regulating metabolism. The adrenal gland is involved in the stress response and producing hormones like cortisol, not primarily regulating metabolism. The pineal gland produces melatonin, which regulates sleep-wake cycles, not metabolism. Therefore, the correct answer is the thyroid gland.

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.