Nokea
What is the primary role of hemoglobin in red blood cells?
- A. Carrying oxygen
- B. Carrying nutrients
- C. Carrying carbon dioxide
- D. Carrying waste products
Correct Answer: A
Rationale: The correct answer is A: Carrying oxygen. Hemoglobin's primary function in red blood cells is to bind with oxygen in the lungs and transport it to the body's tissues and cells. This process is crucial for cellular respiration and the overall oxygenation of the body. Choices B, C, and D are incorrect because hemoglobin primarily carries oxygen, not nutrients, carbon dioxide, or waste products.
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What is the main function of the respiratory system?
- A. To transport nutrients
- B. To regulate body temperature
- C. To absorb oxygen and remove carbon dioxide
- D. To produce energy
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.
What is the primary function of the digestive system?
- A. To transport oxygen
- B. To break down food and absorb nutrients
- C. To produce hormones
- D. To transport blood
Correct Answer: B
Rationale: The primary function of the digestive system is to break down food into smaller molecules and absorb nutrients such as vitamins, minerals, carbohydrates, proteins, and fats. These nutrients are then utilized by the body for energy, growth, and repair. The digestive system plays a crucial role in the process of extracting essential components from food and distributing them to the body's cells through the bloodstream. Choices A, C, and D are incorrect because transporting oxygen, producing hormones, and transporting blood are functions associated with other body systems like the respiratory system, endocrine system, and circulatory system, respectively, not the digestive system.
Which gland produces melatonin?
- A. Pineal gland
- B. Thyroid gland
- C. Adrenal gland
- D. Pituitary gland
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.
Which vitamin is necessary for calcium absorption?
- A. Vitamin A
- B. Vitamin C
- C. Vitamin D
- D. Vitamin K
Correct Answer: C
Rationale: Vitamin D is essential for the absorption of calcium in the intestines, aiding in the maintenance of strong bones and teeth. It helps regulate calcium and phosphorus levels in the body, supporting bone health and preventing conditions like osteoporosis. Vitamin A (Choice A) is important for vision and immune function, not specifically for calcium absorption. Vitamin C (Choice B) is crucial for collagen synthesis and immune function but is not directly involved in calcium absorption. Vitamin K (Choice D) plays a role in blood clotting and bone health, but it is not primarily responsible for calcium absorption.
Which of the following is not a component of the central nervous system?
- A. Brain
- B. Heart
- C. Retina
- D. Spinal cord
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.