Nokea
What is the primary function of hemoglobin in the blood?
- A. Transporting oxygen
- B. Carrying nutrients
- C. Clotting blood
- D. Removing carbon dioxide
Correct Answer: A
Rationale: The correct answer is A: Transporting oxygen. Hemoglobin, a protein found in red blood cells, plays a crucial role in transporting oxygen in the blood. It binds to oxygen in the lungs forming oxyhemoglobin and carries it to tissues and organs throughout the body. Once at the destination, hemoglobin releases the oxygen for cellular respiration, providing energy for various physiological processes. Choices B, C, and D are incorrect as hemoglobin's primary function is not carrying nutrients, clotting blood, or removing carbon dioxide. These functions are carried out by other components in the blood such as plasma proteins, platelets, and red blood cells, respectively.
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What is the role of the alveoli in the lungs?
- A. To filter blood
- B. To exchange gases
- C. To transport nutrients
- D. To store oxygen
Correct Answer: B
Rationale: The alveoli in the lungs are tiny air sacs responsible for the exchange of oxygen and carbon dioxide during breathing. Oxygen from inhaled air diffuses into the bloodstream through the alveoli, while carbon dioxide produced by cells is removed from the blood and exhaled out of the body through the alveoli. This gas exchange process is essential for the body to obtain oxygen and get rid of carbon dioxide, supporting cellular functions and maintaining overall health. Choices A, C, and D are incorrect because the alveoli do not filter blood, transport nutrients, or store oxygen. Their main function is gas exchange.
Which structure in the eye is responsible for focusing light on the retina?
- A. Cornea
- B. Lens
- C. Retina
- D. Pupil
Correct Answer: B
Rationale: The lens of the eye is responsible for focusing light onto the retina. It plays a crucial role in bending light rays to ensure that they converge on the retina, enabling clear vision. The cornea helps in focusing light, but the final adjustment and fine-tuning occur through the lens. The retina receives the focused light and converts it into neural signals for the brain to interpret. The pupil, on the other hand, controls the amount of light entering the eye by dilating or constricting.
What is the primary function of the integumentary system?
- A. Protecting the body from external damage
- B. Regulating body temperature
- C. Producing vitamin D
- D. Producing red blood cells
Correct Answer: A
Rationale: The correct answer is A: Protecting the body from external damage. The primary function of the integumentary system, which includes the skin, hair, and nails, is to act as a physical barrier that protects the body from external damage such as pathogens, UV radiation, and mechanical injuries. While the integumentary system does play roles in regulating body temperature and producing vitamin D, its main and most crucial function is to provide a protective shield for the body. Choices B, C, and D are incorrect because although the integumentary system contributes to regulating body temperature and producing vitamin D, as well as housing cells involved in the immune response, its primary role is protection.
What is the primary function of the kidneys in the urinary system?
- A. To filter waste from the blood
- B. To produce urine
- C. To regulate blood pressure
- D. To absorb nutrients
Correct Answer: A
Rationale: The correct answer is A: 'To filter waste from the blood.' The primary function of the kidneys in the urinary system is to filter waste products and excess substances from the blood, forming urine, which is then excreted from the body. Kidneys play a crucial role in maintaining the body's overall balance by filtering out waste, regulating fluid levels, and helping in the elimination of toxins. Choices B, C, and D are incorrect because while the kidneys do produce urine, regulate blood pressure, and help in nutrient absorption indirectly, their primary function is the filtration of waste from the blood.
Which gland produces the hormone melatonin?
- A. Pineal gland
- B. Thyroid gland
- C. Pituitary gland
- D. Adrenal gland
Correct Answer: A
Rationale: The correct answer is the Pineal gland. The pineal gland is responsible for producing melatonin, a hormone that helps regulate the sleep-wake cycle. Melatonin secretion is influenced by light exposure. Higher levels are observed at night to promote sleep, while lower levels during the day encourage wakefulness. Choices B, C, and D are incorrect as they are not associated with the production of melatonin. The thyroid gland produces hormones like thyroxine and triiodothyronine, the pituitary gland controls various other glands, and the adrenal gland produces hormones like adrenaline and cortisol.