Nursing Elites

1. Which enzyme plays a crucial role in DNA replication during the S phase of interphase?

• A. Helicase
• B. DNA polymerase
• C. Ligase
• D. Topoisomerase

Correct answer: B

Rationale: During the S phase of interphase, DNA replication takes place. DNA polymerase is the enzyme responsible for synthesizing new DNA strands by adding nucleotides in a complementary manner to the template strand. It plays a pivotal role in accurately replicating the entire genome. While helicase unwinds the double-stranded DNA for replication, topoisomerase relieves the tension in the DNA strands, and ligase joins the Okazaki fragments on the lagging strand. However, DNA polymerase directly participates in the synthesis of new DNA strands during replication, making it the correct answer.

2. Which structure in the respiratory system is responsible for gas exchange?

• A. Trachea
• B. Alveoli
• C. Bronchi
• D. Diaphragm

Correct answer: B

Rationale: The alveoli in the lungs are responsible for gas exchange. Alveoli have a rich blood supply and thin walls, enabling the exchange of oxygen and carbon dioxide. Oxygen diffuses into the blood from the alveoli, while carbon dioxide diffuses out. The trachea functions as an air passage, bronchi are the main airways into the lungs, and the diaphragm is the primary muscle involved in breathing by aiding in lung expansion and contraction, but they are not directly responsible for gas exchange like the alveoli.

3. What information can be obtained directly from the element's atomic number?

• A. Its atomic mass
• B. Its position on the periodic table
• C. Its number of neutrons
• D. Its chemical properties

Correct answer: B

Rationale: The atomic number of an element represents the number of protons in the nucleus of an atom. This number determines the element's unique identity and its position on the periodic table. The atomic mass (option A) is not directly determined by the atomic number but is a weighted average of the isotopes of an element. The number of neutrons (option C) is not directly provided by the atomic number but can be calculated by subtracting the atomic number from the atomic mass. The position on the periodic table (option B) is directly related to the atomic number, as elements are arranged in order of increasing atomic number. The chemical properties of an element (option D) are influenced by the number of protons in the nucleus, which is determined by the atomic number.

4. Find the lowest coefficients that will balance the following combustion equation: __C H + __O2 → __CO2 + __H2O

• A. 1:5:5:2
• B. 4:10:20:8
• C. 2:9:10:4
• D. 2:5:10:4

Correct answer: C

Rationale: To balance the combustion equation CxHy + O2 → xCO2 + y/2 H2O, we need to balance the carbon and hydrogen atoms. The balanced equation for the given combustion is: 2C H4 + 9O2 → 2CO2 + 4H2O. This means that the correct coefficients are 2:9:10:4, which corresponds to choice C. Choice A (1:5:5:2) does not balance the equation correctly, choice B (4:10:20:8) has excessive oxygen and does not balance the equation, and choice D (2:5:10:4) does not provide the correct ratio of oxygen to balance the equation.

5. What does nuclear binding energy represent?

• A. Separate an electron from its atom
• B. Separate protons and neutrons within a nucleus
• C. Cause nuclear fission
• D. Induce nuclear fusion

Correct answer: B

Rationale: Nuclear binding energy represents the energy required to hold protons and neutrons together within a nucleus. This energy is needed to overcome the electrostatic repulsion between positively charged protons and keep the nucleus stable. Choices A, C, and D are incorrect. Choice A relates to ionization energy, which is the energy required to remove an electron from an atom. Choices C and D refer to nuclear reactions (fission and fusion), which involve processes different from the concept of nuclear binding energy.

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