Nursing Elites

1. How many mL of a 0 M stock solution of HCl should be added to water to create 250 mL of a 50 M solution of HCl?

• A. 31.25 mL
• B. 32 mL
• C. 30 mL
• D. 31.3 mL

Correct answer: B

Rationale: To prepare 250 mL of a 50 M solution of HCl, the formula V1 x C1 = V2 x C2 is used, where V1 is the volume of the stock solution, C1 is the concentration of the stock solution, V2 is the final volume of the desired solution, and C2 is the final concentration of the desired solution. Given V1 x 0 M = 250 mL x 50 M, solving for V1 results in V1 = (250 mL x 50 M) / 0 M = 32 mL. Therefore, 32 mL of the 0 M stock solution of HCl needs to be added to water to create a 250 mL solution of 50 M HCl. Choices A, C, and D are incorrect because they do not represent the accurate volume required for the dilution calculation based on the given concentrations and volumes in the problem.

2. The lymphatic system is a network of vessels and organs that plays a vital role in:

• A. Transporting oxygen and nutrients to cells
• B. Carrying waste products away from tissues
• C. Regulating body temperature
• D. Producing red blood cells

Correct answer: B

Rationale: The correct answer is B: Carrying waste products away from tissues. The lymphatic system functions to maintain fluid balance in the body by removing excess fluid, filtering out harmful substances, and transporting waste products away from tissues. It does not primarily focus on transporting oxygen and nutrients to cells, regulating body temperature, or producing red blood cells. Choices A, C, and D are incorrect as the primary function of the lymphatic system is related to waste removal and maintaining fluid balance in the body, rather than roles such as nutrient transport, temperature regulation, or red blood cell production.

3. Which cells myelinate neurons in the CNS?

• A. Schwann cells
• B. Astrocytes
• C. Microglia
• D. Oligodendrocytes

Correct answer: D

Rationale: The correct answer is D, Oligodendrocytes. Oligodendrocytes are responsible for myelinating neurons in the central nervous system (CNS). Schwann cells, found in the peripheral nervous system, are responsible for myelinating neurons there. Astrocytes support and maintain the neuronal environment, while microglia function as immune cells in the CNS, participating in immune responses and cellular debris clearance. Therefore, choices A, B, and C are incorrect for myelination of CNS neurons.

4. How are kidney stones formed?

• A. Due to excess water not being reabsorbed
• B. When minerals crystallize in the urine
• C. When electrolytes become too concentrated
• D. All of the above

Correct answer: B

Rationale: Kidney stones are formed when minerals in the urine crystallize and stick together to form solid masses. Excess water not being reabsorbed (option A) does not directly contribute to kidney stone formation. Similarly, electrolytes becoming too concentrated (option C) is not a direct cause of kidney stone formation. The correct answer is B because the crystallization of minerals in the urine leads to the formation of kidney stones.

5. Which of the following is NOT a recognized mode of natural selection?

• A. Directional selection (favoring one extreme trait value on a spectrum)
• B. Disruptive selection (favoring both extreme trait values on a spectrum)
• C. Stabilizing selection (favoring the average trait value on a spectrum)
• D. Sexual selection (selection based on mate choice that influences reproductive success)

Correct answer: D

Rationale: A) Directional selection is a recognized mode of natural selection where one extreme trait value on a spectrum is favored over others, leading to a shift in the average trait value over time. B) Disruptive selection is a recognized mode of natural selection where both extreme trait values on a spectrum are favored over the average trait value, potentially causing the population to split into distinct groups. C) Stabilizing selection is a recognized mode of natural selection favoring the average trait value on a spectrum over extreme values, resulting in reduced genetic diversity. D) Sexual selection differs from traditional natural selection modes as it involves mate choice and competition for mates, not direct selection pressure on traits affecting survival and reproduction in the environment. Sexual selection can drive the evolution of traits enhancing an individual's attractiveness for mating purposes.

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