Which of the following is not a component of the central nervous system?

Correct Answer: B

Rationale: The central nervous system comprises the brain and spinal cord, responsible for processing and transmitting information. The retina, though part of the eye, is an extension of the central nervous system. However, the heart is part of the circulatory system, responsible for pumping blood throughout the body. Therefore, the correct answer is the heart as it is not a component of the central nervous system.

Correct Answer: B

Rationale: The primary function of the skin is to protect the body from external damage. While the skin also helps regulate body temperature and produces vitamin D in response to sunlight, its main role is to act as a barrier against harmful external factors, such as pathogens and physical injuries. Choices A, C, and D are incorrect because although the skin does play a role in regulating body temperature and producing vitamin D, its primary function is providing protection against external threats.

Correct Answer: A

Rationale: The correct answer is A: To secrete digestive enzymes. The pancreas is responsible for secreting digestive enzymes that aid in breaking down carbohydrates, fats, and proteins in the small intestine, facilitating the process of digestion. Choice B is incorrect because the pancreas does not store bile; that is primarily the function of the gallbladder. Choice C is incorrect as the absorption of nutrients mainly occurs in the small intestine, not the pancreas. Choice D is incorrect as the transport of glucose is primarily regulated by insulin produced in the pancreas, but this is not the main role of the pancreas in digestion.

Correct Answer: B

Rationale: The correct function of the lungs in the respiratory system is to exchange gases. The lungs facilitate the exchange of oxygen and carbon dioxide between the air we breathe in and the blood, ensuring oxygen is absorbed and carbon dioxide is removed during respiration. Choice A is incorrect as the kidneys, not the lungs, filter blood. Choice C is incorrect as energy production primarily occurs in cells, not in the lungs. Choice D is incorrect as waste removal, such as the excretion of carbon dioxide, is a function of the lungs, but the primary function is the exchange of gases.

Correct Answer: B

Rationale: The correct answer is B: Remove carbon dioxide from the body. The primary function of the lymphatic system is to return excess tissue fluid to the bloodstream and assist in the body's defense against infections by filtering out harmful pathogens and foreign particles. Choices A, C, and D are incorrect because transporting oxygen to cells is mainly done by the circulatory system, hormone production is primarily carried out by endocrine glands, and nutrient transport is also a function of the circulatory system and the digestive system, not the lymphatic system.

Correct Answer: A

Rationale: The correct answer is the Pineal gland. This gland is responsible for producing melatonin, a hormone that helps regulate the sleep-wake cycle. Melatonin production is influenced by exposure to light, with levels typically rising in the evening to promote sleep and falling in the morning to aid wakefulness. The Thyroid gland (choice B) produces hormones that regulate metabolism, the Adrenal gland (choice C) produces hormones like adrenaline and cortisol, and the Pituitary gland (choice D) controls several other glands in the endocrine system.

Correct Answer: C

Rationale: The main function of the respiratory system is to absorb oxygen from the air into the bloodstream and remove carbon dioxide from the body. Oxygen is essential for cellular respiration, the process through which cells generate energy. Carbon dioxide is a waste product expelled during this process. Choice A, 'To transport nutrients,' is incorrect as the respiratory system is not primarily responsible for transporting nutrients. Choice B, 'To regulate body temperature,' is incorrect as the respiratory system's main role is not temperature regulation. Choice D, 'To produce energy,' is incorrect because while oxygen obtained through respiration is used in the energy production process, the respiratory system itself does not directly produce energy.

Correct Answer: B

Rationale: Platelets, also known as thrombocytes, are responsible for clotting blood. When there is an injury, platelets help form blood clots to prevent excessive bleeding. This function is crucial in maintaining hemostasis and preventing hemorrhage. Choices A, C, and D are incorrect. Platelets do not transport oxygen, fight infection, or transport nutrients in the blood.

Correct Answer: B

Rationale: The adrenal glands function to produce hormones such as adrenaline and cortisol. These hormones play essential roles in regulating metabolism, immune response, and the body's response to stress. Therefore, the correct answer is that the adrenal glands produce hormones. Choices A, C, and D are incorrect as regulating blood sugar is primarily done by the pancreas, producing red blood cells is the function of the bone marrow, and filtering blood is carried out by the kidneys, not the adrenal glands.