Nokea
Which hormone is released by the posterior pituitary gland?
- A. Oxytocin
- B. Thyroxine
- C. Insulin
- D. ADH
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.
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Which type of muscle is found in the walls of hollow organs?
- A. Skeletal muscle
- B. Cardiac muscle
- C. Smooth muscle
- D. Striated muscle
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.
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 responsible for regulating blood sugar levels?
- A. Insulin
- B. Glucagon
- C. Thyroxine
- D. Melatonin
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.
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.
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.