What is the primary function of platelets?

Correct Answer: B

Rationale: The primary function of platelets, or thrombocytes, is to clot blood. Platelets play a crucial role in hemostasis by forming clots to prevent excessive bleeding when injuries occur. They are not directly involved in fighting infections, carrying oxygen, or transporting nutrients. Therefore, the correct answer is B.

Correct Answer: B

Rationale: The central nervous system consists of the brain and spinal cord, which are responsible for processing and coordinating information. The retina is part of the eye, while the heart is part of the circulatory system. Therefore, the correct answer is 'Spinal cord' as it is not part of the central nervous system.

Correct Answer: B

Rationale: The medulla oblongata, located in the brainstem, plays a crucial role in controlling vital functions such as breathing, heart rate, and blood pressure. It serves as the control center for automatic functions necessary for survival, making it the correct choice in this scenario. The cerebrum is responsible for higher brain functions like thinking and voluntary movements, so it does not control basic physiological functions like breathing and heart rate. The cerebellum is mainly involved in coordination and balance, while the hypothalamus regulates body temperature, hunger, and thirst, but not specifically breathing and heart rate.

Correct Answer: B

Rationale: The glomerulus is a key structure in the kidney responsible for filtering blood. It consists of a network of capillaries that filter waste products and excess substances from the blood, allowing the formation of urine. While the nephron, Bowman's capsule, and Loop of Henle are also essential components of the kidney's filtration system, the glomerulus is specifically involved in the initial blood filtration process. The nephron is the functional unit of the kidney, Bowman's capsule surrounds the glomerulus and collects the filtrate, and the Loop of Henle is responsible for reabsorption and concentration of urine, not the initial blood filtration.

Correct Answer: B

Rationale: Calcium and phosphorus are crucial nutrients for bone health as they are essential minerals required for bone strength, density, and various body functions. Adequate intake of calcium and phosphorus through the diet is important for maintaining healthy bones and preventing conditions like osteoporosis. Vitamin D helps with calcium absorption, but it is not the main nutrient responsible for bone health. Iron and zinc are important for other bodily functions, not specifically bone health. Magnesium and sodium, while important for overall health, are not as directly linked to bone health as calcium and phosphorus.

Correct Answer: A

Rationale: The spleen plays a crucial role in the immune system by filtering blood, specifically removing old or damaged red blood cells. It also stores lymphocytes, which are white blood cells that help fight infections. While the spleen does not produce white blood cells or antibodies, its main functions lie in blood filtration and storage of immune cells. Therefore, the correct answer is A. Choice B is incorrect because the spleen does not produce white blood cells. Choice C is incorrect as the spleen stores lymphocytes but does not primarily function to do so. Choice D is incorrect because the spleen does not produce antibodies.

Correct Answer: B

Rationale: The primary function of platelets, or thrombocytes, is to clot blood. Platelets play a crucial role in hemostasis by forming clots to prevent excessive bleeding when injuries occur. They are not directly involved in fighting infections, carrying oxygen, or transporting nutrients. Therefore, the correct answer is B.

Correct Answer: A

Rationale: The correct answer is 'Larynx.' The larynx is indeed located in the upper respiratory system alongside the pharynx. Positioned below the pharynx and above the trachea, the larynx is crucial for breathing and sound production. The trachea and bronchi are part of the lower respiratory system and are situated below the larynx, making them incorrect choices in this context.

Correct Answer: D

Rationale: The larynx is a vital organ of the respiratory system, responsible for producing sound and connecting the pharynx to the trachea. It plays a crucial role in breathing, swallowing, and vocalization. The brain, pancreas, and urethra are not part of the respiratory system; the brain is part of the nervous system, the pancreas is part of the digestive system, and the urethra is part of the urinary system. Therefore, the correct answer is the larynx.