Nokea
Where are B-lymphocytes produced?
- A. Thymus
- B. Red bone marrow
- C. Lymph nodes
- D. Spleen
Correct Answer: B
Rationale: B-lymphocytes are produced in the red bone marrow. The red bone marrow is the primary site for B-cell development, where they mature before entering the circulation. The thymus is responsible for T-lymphocyte maturation, not B-lymphocytes. Lymph nodes and spleen play roles in immune responses but are not the primary sites for B-lymphocyte production.
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What is the primary function of white blood cells?
- A. To carry oxygen
- B. To fight infections
- C. To transport nutrients
- D. To clot blood
Correct Answer: B
Rationale: White blood cells, also known as leukocytes, play a crucial role in the immune system by primarily fighting off infections caused by pathogens like bacteria, viruses, and other invaders. They help the body recognize and destroy these harmful agents, contributing to the body's defense mechanisms against diseases. Choice A is incorrect because the primary function of red blood cells, not white blood cells, is to carry oxygen. Choice C is incorrect as the transportation of nutrients is mainly carried out by the bloodstream as a whole, not specifically by white blood cells. Choice D is incorrect as the process of blood clotting is primarily managed by platelets in the blood, not white blood cells.
Which of the following structures is located in the respiratory system?
- A. Larynx
- B. Trachea
- C. Pharynx
- D. Esophagus
Correct Answer: A
Rationale: The larynx, also known as the voice box, is a crucial structure in the respiratory system. It is located in the upper part of the trachea and houses the vocal cords. The larynx plays a key role in producing sound and protecting the trachea by closing during swallowing to prevent food from entering the airway. This makes the larynx the correct answer in this context. The trachea (Choice B) is a respiratory structure that connects the larynx to the lungs, allowing air to pass through. The pharynx (Choice C) is a shared pathway for both air and food, located at the back of the throat. The esophagus (Choice D) is part of the digestive system, responsible for transporting food from the mouth to the stomach. Therefore, Choices B, C, and D are not located in the respiratory system.
What is the primary role of the large intestine?
- A. To absorb nutrients
- B. To absorb water
- C. To break down food
- D. To secrete digestive enzymes
Correct Answer: B
Rationale: The correct answer is B: To absorb water. The primary role of the large intestine is to absorb water from indigestible food matter. This absorption process helps in forming solid waste for excretion. Nutrient absorption primarily occurs in the small intestine, not the large intestine. Breaking down food and secreting digestive enzymes are functions primarily associated with the stomach and small intestine.
Which vitamin is essential for the synthesis of collagen?
- A. Vitamin C
- B. Vitamin D
- C. Vitamin B12
- D. Vitamin K
Correct Answer: A
Rationale: The correct answer is Vitamin C. Vitamin C is essential for the synthesis of collagen, a protein crucial for maintaining the structure and integrity of skin, blood vessels, and bones. It plays a key role in the hydroxylation of proline and lysine residues in collagen synthesis, which is necessary for the stability and strength of collagen fibers.
Choice B: Vitamin D is essential for bone health and calcium absorption but is not directly involved in collagen synthesis.
Choice C: Vitamin B12 is important for red blood cell formation and neurological function but is not directly related to collagen synthesis.
Choice D: Vitamin K is necessary for blood clotting and bone metabolism but does not play a direct role in collagen synthesis.
Which muscle is responsible for the extension of the elbow?
- A. Biceps brachii
- B. Triceps brachii
- C. Deltoid
- D. Pectoralis major
Correct Answer: B
Rationale: The correct answer is B: Triceps brachii. The triceps brachii muscle is responsible for extending the elbow joint. It is located on the back of the upper arm and acts in opposition to the biceps brachii, which is responsible for elbow flexion. The deltoid muscle is primarily responsible for shoulder abduction, not elbow extension. The pectoralis major muscle is involved in movements of the shoulder joint, not the elbow.