Nursing Elites

1. The term "bioaccumulate" refers to...

• A. The natural decomposition of organic materials.
• B. The buildup of a substance in living organisms.
• C. The contamination of seawater with chemical pollutants.
• D. The physical entanglement of animals with plastic debris.

Correct answer: B

Rationale: The passage describes microplastics entering food chains and accumulating in organisms, aligning with bioaccumulation.

2. In a covalent bond, the shared electrons:

• A. Are completely transferred to one atom.
• B. Spend more time closer to the more electronegative atom.
• C. Remain equidistant between the two atoms.
• D. Do not influence the bond strength.

Correct answer: B

Rationale: Spend more time closer to the more electronegative atom. Electronegativity determines the "pull" on shared electrons, with the more electronegative atom attracting them for a larger portion of the time, creating a partial negative charge near its nucleus.

3. In the reaction 2Na + 2H2O → 2NaOH + H2, what is the limiting reactant when 3 moles of sodium react with 2 moles of water?

• A. Na
• B. H2O
• C. NaOH
• D. H2

Correct answer: a

Rationale: Sodium is the limiting reactant because it runs out first in a 1:1 ratio with water.

4. Which part of the heart generates the QRS complex on an ECG?

• A. Sinoatrial node (SA node)
• B. Atrioventricular node (AV node)
• C. Bundle of His
• D. Ventricular muscle cells

Correct answer: D

Rationale: The correct answer is D, ventricular muscle cells. The QRS complex on an ECG represents the depolarization of the ventricles. This electrical activity is generated by the spread of impulses through the bundle branches and Purkinje fibers to the ventricular muscle cells. The SA node (option A) is responsible for initiating the electrical impulse in the heart, but it does not directly generate the QRS complex. The AV node (option B) delays the impulse to allow for proper coordination of atrial and ventricular contractions. The Bundle of His (option C) and its branches facilitate the conduction of the electrical signal from the AV node to the ventricles but do not generate the QRS complex directly.

5. A hypothesis should be:

• A. A definitive statement of fact based on existing knowledge.
• B. A testable prediction based on observations and reasoning.
• C. A broad question without any specific direction or focus.
• D. A personal belief or opinion not requiring further investigation.

Correct answer: B

Rationale: Hypotheses guide scientific exploration by providing a framework for testing potential explanations.

6. Which term refers to the condition where a muscle shortens in length while generating force, leading to movement at a joint?

• A. Isometric contraction
• B. Eccentric contraction
• C. Isotonic contraction
• D. Concentric contraction

Correct answer: d

Rationale: The correct answer is D: Concentric contraction. Concentric contraction occurs when a muscle shortens in length while generating force, resulting in movement at a joint. This type of contraction is commonly seen when lifting a weight in a bicep curl, for example. Isometric contraction, option A, refers to when the muscle generates force without changing length, eccentric contraction, option B, is when the muscle lengthens while generating force, and isotonic contraction, option C, involves the muscle maintaining a constant tension while changing length. Therefore, in the context of muscle movement and joint action, concentric contraction best describes the condition described in the question.

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