Nursing Elites

1. What term describes the functional unit of a skeletal muscle responsible for muscle contraction?

• A. Myofibril
• B. Sarcomere
• C. Tendon
• D. Myoglobin

Correct answer: B

Rationale: The correct answer is B, 'Sarcomere.' The sarcomere is indeed the functional unit of a skeletal muscle responsible for muscle contraction. It is composed of actin and myosin filaments that interact to generate muscle contraction. Choice A, 'Myofibril,' is incorrect as myofibrils are composed of sarcomeres, not the functional units themselves. Choice C, 'Tendon,' is incorrect as tendons connect muscles to bones and do not directly participate in muscle contraction. Choice D, 'Myoglobin,' is incorrect as myoglobin is a protein that stores oxygen in muscle cells and is not directly involved in muscle contraction.

2. How many moles of oxygen are required to completely react with 5 moles of propane (C3H8) in the combustion reaction?

• A. 5 moles
• B. 10 moles
• C. 15 moles
• D. 20 moles

Correct answer: C

Rationale: In the balanced chemical equation for the combustion of propane (C3H8): C3H8 + 5O2 → 3CO2 + 4H2O, 1 mole of propane (C3H8) reacts with 5 moles of oxygen (O2). To determine the moles of oxygen required to react with 5 moles of propane, we use the molar ratio: 5 moles propane x 5 moles oxygen / 1 mole propane = 25 moles oxygen. However, since the question specifically asks for the moles of oxygen needed to react with 5 moles of propane, the correct answer is 15 moles of oxygen. Choice A, 5 moles, is incorrect because this is the amount of propane provided, not the oxygen required. Choice B, 10 moles, is incorrect as it does not correspond to the molar ratio in the balanced equation. Choice D, 20 moles, is incorrect as it is not in line with the stoichiometry of the reaction.

3. Which body system is responsible for the transport of dissolved oxygen from the lungs to the spleen?

• A. Immune
• B. Endocrine
• C. Respiratory
• D. Cardiovascular

Correct answer: D

Rationale: The correct answer is the cardiovascular system (Option D). The cardiovascular system is responsible for transporting oxygenated blood from the lungs, where oxygen is absorbed, to various tissues and organs in the body, including the spleen. The immune system (Option A) is responsible for defending the body against infections and diseases. The endocrine system (Option B) regulates hormones and their effects on the body. The respiratory system (Option C) is responsible for the exchange of gases, such as oxygen and carbon dioxide, in the lungs.

4. What is the function of valves in arteries?

• A. To maintain high blood pressure for the proper diffusion of nutrients in capillaries.
• B. To prevent backflow of blood due to high pressure away from the heart.
• C. As a vestigial trait from evolution, like the appendix, that serves no purpose.
• D. Valves are absent in arteries but present in veins.

Correct answer: B

Rationale: Valves in arteries serve the crucial function of preventing backflow of blood. Arteries carry blood at high pressure away from the heart, and the valves ensure that blood flows in one direction, towards the capillaries, to maintain efficient circulation. Without these valves, there would be a risk of blood flowing backward, compromising the effectiveness of blood circulation in the body. Choices A, C, and D are incorrect. Choice A incorrectly suggests that valves maintain high blood pressure for nutrient diffusion in capillaries, which is not their function. Choice C inaccurately compares valves to vestigial traits, like the appendix, implying they serve no purpose, which is untrue. Choice D is incorrect as valves are indeed present in arteries to regulate blood flow, not just in veins.

5. After water absorption in the large intestine, what waste product remains and is eventually eliminated from the body?

• A. Chyme
• B. Bolus
• C. Glucose
• D. Feces

Correct answer: D

Rationale: The correct answer is D: Feces. After the large intestine absorbs water and electrolytes from digested food material, the waste product that remains is feces. Feces consist of undigested food material, bacteria, and waste products that were not absorbed by the body. Choice A, Chyme, is incorrect as chyme is a semi-fluid mass of partially digested food that moves from the stomach to the small intestine. Choice B, Bolus, is incorrect as bolus refers to a rounded mass of food that is swallowed. Choice C, Glucose, is incorrect as glucose is a simple sugar that serves as a vital energy source for the body and is not a waste product in this context.

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