Nokea
Which vitamin is essential for the absorption of calcium?
- A. Vitamin A
- B. Vitamin D
- C. Vitamin K
- D. Vitamin C
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.
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Which hormone is responsible for regulating the sleep-wake cycle?
- A. Melatonin
- B. Thyroxine
- C. Insulin
- D. Cortisol
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.
What type of tissue forms the outer layer of the skin?
- A. Connective tissue
- B. Epithelial tissue
- C. Muscle tissue
- D. Nervous tissue
Correct Answer: B
Rationale: Epithelial tissue is the correct answer. It forms the outer layer of the skin, serving as a protective barrier against pathogens and environmental damage. This tissue type is essential for maintaining skin integrity and plays a crucial role in skin function. Connective tissue (Choice A), although important for providing support and structure, does not form the outer layer of the skin. Muscle tissue (Choice C) is responsible for movement and is not the primary tissue in the skin. Nervous tissue (Choice D) is involved in transmitting signals but is not the main component of the skin's outer layer.
What is the primary function of the skeletal system?
- A. To produce blood cells
- B. To protect organs
- C. To store fat
- D. To secrete hormones
Correct Answer: B
Rationale: The primary function of the skeletal system is to protect vital organs, provide structural support, and enable movement. It serves as a framework that supports and protects internal organs, such as the brain, heart, and lungs. Choice A is incorrect because blood cell production primarily occurs in the bone marrow, a component of the skeletal system but not its primary function. Choice C is incorrect because fat storage is not a primary function of the skeletal system. Choice D is incorrect because hormone secretion is mainly regulated by endocrine glands, not the skeletal system.
Which hormone is produced by the thyroid gland?
- A. Insulin
- B. Thyroxine
- C. Glucagon
- D. Cortisol
Correct Answer: B
Rationale: Thyroxine is the hormone produced by the thyroid gland. It plays a crucial role in regulating metabolism, heart rate, and growth. Insulin is produced by the pancreas to regulate blood sugar levels, not by the thyroid gland. Glucagon is also produced by the pancreas and helps increase blood sugar levels. Cortisol is produced by the adrenal glands and is involved in stress response and metabolism, not by the thyroid gland.
Which of the following structures regulates the transport of substances in and out of a cell?
- A. Nucleus
- B. Cell membrane
- C. Cytoplasm
- D. Mitochondria
Correct Answer: B
Rationale: The cell membrane, also known as the plasma membrane, is responsible for regulating the transport of substances in and out of the cell. It acts as a selective barrier, allowing the passage of certain molecules while restricting others. This selective permeability helps maintain homeostasis within the cell by controlling the movement of essential substances like nutrients and waste products. The nucleus (Choice A) is the organelle that houses the cell's genetic material and is not directly involved in regulating substance transport. Cytoplasm (Choice C) is the gel-like substance that fills the cell and does not play a direct role in regulating substance transport. Mitochondria (Choice D) are responsible for energy production in the cell through cellular respiration and are not primarily involved in substance transport.