Nursing Elites

1. Which of the following structures helps filter pathogens from the blood?

• A. Lymph nodes
• B. Kidneys
• C. Spleen
• D. Pancreas

Correct answer: C

Rationale: The spleen is the correct answer. The spleen is a vital organ in the immune system responsible for filtering pathogens from the blood. It contains specialized immune cells that aid in recognizing and eliminating harmful substances. Additionally, the spleen plays a role in recycling old red blood cells. Choices A, B, and D are incorrect. Lymph nodes primarily filter lymph fluid, not blood. Kidneys are involved in filtering waste and regulating fluid balance, not specifically filtering pathogens from the blood. The pancreas functions in hormone regulation and digestion, unrelated to filtering pathogens from the blood.

2. Which statement is true about the pH of a solution?

• A. A solution cannot have a pH less than 0.
• B. A solution always has a pH of 7.
• C. A solution's pH is not influenced by its chemical composition.
• D. A solution with a pH of 14 is considered acidic.

Correct answer: A

Rationale: The pH scale ranges from 0 to 14, with 0 being the most acidic, 7 neutral, and 14 the most basic. A solution with a pH less than 0 would be outside the defined pH range, as 0 is the lower limit. Therefore, a solution cannot have a pH less than 0. Choice B is incorrect because a pH of 7 is considered neutral, not always the pH of a solution. Choice C is incorrect because a solution's pH is influenced by its chemical composition. Choice D is incorrect as a solution with a pH of 14 is considered highly basic, not acidic.

3. If a scientist finds that the results of her experiment seem to contradict her hypothesis, what is the best course of action?

• A. Publish the results anyway, acknowledging that her hypothesis seems to have been incorrect.
• B. Keep trying the experiment until the results match her hypothesis.
• C. Publish the results, retroactively changing the hypothesis.
• D. None of the above; this cannot occur. The experimental results cannot contradict the hypothesis, by definition.

Correct answer: A

Rationale: The best course of action is to publish the results anyway, acknowledging that her hypothesis seems to have been incorrect. Science relies on accurate reporting and transparency, even if the results do not align with the original hypothesis. This allows for further discussion, analysis, and potentially new hypotheses to be developed based on the findings. It is essential in scientific research to report both positive and negative results to contribute to the body of knowledge and advance understanding in the field. Choice B is incorrect because persisting with the same experiment to force results to align with the hypothesis goes against scientific integrity and may lead to biased conclusions. Choice C is incorrect as changing the hypothesis after obtaining results is not scientifically sound and undermines the credibility of the research. Choice D is incorrect because science embraces the possibility of experimental results contradicting hypotheses, as this provides valuable insights for refining theories and expanding scientific knowledge.

4. The Gram stain is a differential staining technique used to classify bacteria based on their cell wall composition. Gram-positive bacteria appear

• A. Pink
• B. Blue
• C. Red
• D. Purple

Correct answer: D

Rationale: The Gram stain is a differential staining technique that categorizes bacteria into two groups based on their cell wall composition: Gram-positive and Gram-negative. Gram-positive bacteria have a thick layer of peptidoglycan in their cell walls, which retains the crystal violet stain used in the Gram staining procedure. Consequently, Gram-positive bacteria appear purple under the microscope after staining. On the other hand, Gram-negative bacteria possess a thinner peptidoglycan layer and an outer membrane that can be penetrated by the counterstain safranin, leading them to appear pink or red. Blue is not typically used to describe the color of bacteria in a Gram stain, making it an incorrect choice.

5. What is the difference between DNA and RNA?

• A. Both are double-stranded.
• B. DNA contains deoxyribose sugar, while RNA contains ribose sugar.
• C. RNA contains the nitrogenous base uracil, while DNA contains thymine.
• D. Both are identical molecules.

Correct answer: B

Rationale: A) Incorrect. DNA is double-stranded, but RNA is typically single-stranded. B) Correct. DNA contains deoxyribose sugar, which lacks an oxygen atom on the 2' carbon of the sugar ring, while RNA contains ribose sugar, which has an additional hydroxyl group on the 2' carbon. C) Incorrect. RNA contains the nitrogenous base uracil, while DNA contains thymine. D) Incorrect. DNA and RNA have distinct structures and functions, so they are not identical molecules.

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