Nursing Elites

1. Two mice are both heterozygous for two traits: white fur (Ww) and short fur (Ss). Their offspring are most likely to have which of the following genotypes for these traits?

• A. wwss
• B. WWSS
• C. WwSs
• D. WWSs

Correct answer: C

Rationale: When two mice that are heterozygous for white fur (Ww) and short fur (Ss) mate, they can produce offspring with different combinations of the two traits. The Punnett square for this cross shows that the most likely genotype for the offspring is WwSs. In this case, each offspring receives one allele for white fur (W) and one for short fur (S) from each parent, resulting in a heterozygous genotype for both traits. Choice A (wwss) is incorrect as it represents a homozygous recessive genotype for both traits. Choice B (WWSS) is also incorrect as it represents a homozygous dominant genotype for both traits. Choice D (WWSs) is incorrect as it represents a genotype where one trait is homozygous dominant (W) and the other is heterozygous (S), which is not the most likely outcome based on the given parental genotypes.

2. Which of the following is a representation of a natural pattern or occurrence that is difficult or impossible to experience directly?

• A. A theory
• B. A model
• C. A law
• D. An observation

Correct answer: B

Rationale: A model is a representation of a natural pattern or occurrence that is difficult or impossible to experience directly. Models are used to simplify complex systems or phenomena to aid in understanding or making predictions about them. The other options (A, C, and D) do not specifically refer to representations of natural patterns or occurrences as models do. A theory is an explanation based on observations, experiments, and reasoning. A law is a statement that describes a consistent natural phenomenon observed to occur without exception. An observation is a direct result of perceiving something using the senses, without being a representation or abstraction of a natural pattern.

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. Which statement most accurately compares and contrasts the structures of DNA and RNA?

• A. Both DNA and RNA have 4 nucleotide bases. Three of the bases are the same, but the fourth base is thymine in DNA and uracil in RNA.
• B. Both DNA and RNA have the same 4 nucleotide bases. However, the nucleotides bond differently in DNA compared to RNA.
• C. Both DNA and RNA have different numbers of nucleotide bases. DNA is a double helix while RNA is a single strand.
• D. Both DNA and RNA have a double helix structure. However, DNA contains 6 nucleotide bases and RNA contains 4 nucleotide bases.

Correct answer: A

Rationale: The correct answer is A because DNA and RNA both consist of 4 nucleotide bases, namely adenine, cytosine, and guanine, which are common in both. The key difference lies in the fourth base, which is thymine in DNA and uracil in RNA. This distinction is fundamental in understanding the structural variances between DNA and RNA. Choice B is incorrect as it incorrectly states that the nucleotides bond differently in DNA compared to RNA without specifying the crucial base differences. Choice C is inaccurate as it misrepresents the numbers of nucleotide bases in DNA and RNA, and incorrectly describes DNA as a double helix and RNA as a single strand, which is not related to the difference in bases. Choice D is incorrect as it inaccurately portrays DNA with 6 nucleotide bases and RNA with 4, which is not true; both DNA and RNA have 4 nucleotide bases, but with differences in one of the bases.

5. Why are noble gas elements generally unreactive?

• A. They are too large and cannot form bonds easily.
• B. They lack valence electrons in their outermost shell.
• C. They have strong bonds within their own molecules.
• D. They have already achieved stable electron configurations.

Correct answer: D

Rationale: The correct answer is D. Noble gas elements are generally unreactive because they have already achieved stable electron configurations by having a full outer electron shell. This full shell makes them very stable and unlikely to gain, lose, or share electrons with other elements. Choices A, B, and C are incorrect because noble gases are not unreactive due to being too large to form bonds easily (A), lacking valence electrons in their outermost shell (B), or having strong bonds within their own molecules (C).

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