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.
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What is the primary role of the stomach in the digestive system?
- A. To absorb nutrients
- B. To break down food
- C. To secrete digestive enzymes
- D. To store glucose
Correct Answer: B
Rationale: The primary role of the stomach in the digestive system is to break down food. It accomplishes this through the action of gastric acid and digestive enzymes, which work together to break down food into a semi-liquid mixture known as chyme. Option B, 'To break down food,' is the correct answer. Option A, 'To absorb nutrients,' is incorrect because absorption mainly occurs in the small intestine. Option C, 'To secrete digestive enzymes,' is partially correct as the stomach does secrete digestive enzymes, but its primary function is to break down food. Option D, 'To store glucose,' is incorrect as glucose storage primarily occurs in the liver and muscles, not the stomach.
What is the main function of the skeletal system?
- A. To produce red blood cells
- B. To protect internal organs and provide support
- C. To regulate body temperature
- D. To store calcium
Correct Answer: B
Rationale: The main function of the skeletal system is to provide structural support, protect internal organs, enable movement, and maintain the body's form. Choice A, 'To produce red blood cells,' is incorrect as the skeletal system's role in blood cell production is through the bone marrow, not its main function. Choice C, 'To regulate body temperature,' is incorrect as the skeletal system is not primarily responsible for regulating body temperature. Choice D, 'To store calcium,' is partially correct as the skeletal system does store calcium but this is not its main function; instead, it is essential for bone strength and muscle function.
What is the function of the small intestine?
- A. To store bile
- B. To absorb nutrients
- C. To digest food
- D. To produce enzymes
Correct Answer: B
Rationale: The small intestine is the primary site for nutrient absorption in the digestive system. It is responsible for absorbing nutrients from the digested food into the bloodstream for distribution throughout the body. Therefore, the correct function of the small intestine is to absorb nutrients. Choice A is incorrect because the gallbladder stores bile, not the small intestine. Choice C is incorrect because the digestion process primarily occurs in the stomach and small intestine. Choice D is incorrect because while the small intestine does play a role in enzyme production, its primary function is nutrient absorption.
Which organ in the digestive system absorbs nutrients?
- A. Stomach
- B. Small intestine
- C. Large intestine
- D. Esophagus
Correct Answer: B
Rationale: The small intestine is the primary site for nutrient absorption in the digestive system. It plays a crucial role in absorbing digested food into the bloodstream, where the nutrients are then circulated to the body's cells for energy and other functions. The stomach primarily breaks down food through the action of acids and enzymes, while the large intestine absorbs water and salts, not nutrients. The esophagus is a muscular tube that connects the mouth to the stomach and does not participate in nutrient absorption.
What is the primary function of the lymphatic system?
- A. Transport oxygen to cells
- B. Remove carbon dioxide from the body
- C. Produce hormones
- D. Transport nutrients
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.