Nursing Elites

1. Identify the spectator ions in the reaction: 2KCl + Pb(NO3)2 → 2KNO3 + PbCl2.

• A. K+ and NO3-
• B. K+ and Cl-
• C. Pb2+ and NO3-
• D. Pb2+ and Cl-

Correct answer: B

Rationale: - In the reaction, potassium ions (K+) and chloride ions (Cl-) are present on both sides of the equation. They are not involved in the formation of the products and remain unchanged. - Lead ions (Pb2+) and nitrate ions (NO3-) are involved in the formation of the products potassium nitrate (KNO3) and lead(II) chloride (PbCl2). - Therefore, the spectator ions in this reaction are K+ and Cl-.

2. Based on the following evidence, what is the most likely reason that spoiled food left out in the open often contains fly larvae?

• A. The spoiled food evolves into fly larvae.
• B. Since the food is left out in the open, flies lay eggs in the food.
• C. Fly larvae are spontaneously generated by the spoiled food.
• D. People only imagine they see fly larvae in the spoiled food.

Correct answer: B

Rationale: The correct answer is B. Flies laying eggs in the food when it is left exposed to the air is a common occurrence and a logical explanation for the presence of fly larvae in spoiled food. Choice A is incorrect as food cannot evolve into fly larvae; fly larvae come from eggs laid by flies. Choice C is incorrect as fly larvae do not spontaneously generate from spoiled food but rather develop from eggs laid by flies. Choice D is incorrect as the presence of fly larvae in spoiled food is a real phenomenon, not merely imagined by people.

3. What type of bond holds water molecules together?

• A. Covalent bond
• B. Hydrogen bond
• C. Ionic bond
• D. Peptide bond

Correct answer: B

Rationale: The correct answer is B: Hydrogen bond. Hydrogen bonds are responsible for holding water molecules together. In a water molecule, the oxygen atom is slightly negative, and the hydrogen atoms are slightly positive, creating a partial positive and negative charge. This polarity allows hydrogen bonds to form between adjacent water molecules. Covalent bonds involve the sharing of electrons, ionic bonds involve transfer of electrons between ions, and peptide bonds are specific to linking amino acids in proteins, which are not relevant to water molecule interactions.

4. What are the phases of bacterial growth and infection?

• A. Lag, exponential, stationary, death
• B. Exponential, stationary, lag, death
• C. Stationary, exponential, lag, death
• D. Lag, stationary, exponential, death

Correct answer: A

Rationale: The correct answer is A: Lag, exponential, stationary, death. The phases of bacterial growth start with the lag phase where bacteria acclimate to their environment, followed by the exponential phase characterized by rapid growth. This is then followed by the stationary phase where growth slows as resources deplete, and finally, the death phase where the population declines. Choice B is incorrect as it has the order of phases mixed up. Choice C is incorrect as it also has the order of phases mixed up. Choice D is incorrect as it has the stationary phase occurring before the exponential phase, which is inaccurate.

5. 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.

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