Nursing Elites

1. What is the shape of the DNA molecule?

• A. Linear
• B. Circular
• C. Double helix
• D. Straight chain

Correct answer: C

Rationale: Rationale: The shape of the DNA molecule is a double helix. This structure was first described by James Watson and Francis Crick in 1953. The double helix shape consists of two strands that are twisted around each other in a spiral. This shape allows DNA to be compactly stored within the cell nucleus and provides stability to the molecule. The other options (A) Linear, (B) Circular, and (D) Straight chain do not accurately describe the shape of the DNA molecule.

2. The primary function of the atrioventricular (AV) node within the heart is to:

• A. Generate the electrical impulse for contraction (pacemaker function)
• B. Transmit the electrical impulse from atria to ventricles, regulating the timing of contraction.
• C. Increase blood pressure within the ventricles during systole.
• D. Separate oxygenated and deoxygenated blood flow in the heart.

Correct answer: B

Rationale: The correct answer is B: "Transmit the electrical impulse from atria to ventricles, regulating the timing of contraction." The AV node acts as a gateway between the atria and ventricles, ensuring a coordinated and sequential contraction of the heart chambers. It delays the conduction of electrical impulses to allow the atria to fully contract before the ventricles contract, facilitating efficient blood pumping. Options A, C, and D are incorrect because the primary role of the AV node is not to generate electrical impulses, increase blood pressure, or separate blood flow based on oxygenation status. Understanding the AV node's function is crucial in comprehending the heart's electrical conduction system.

3. Nuclear fission is a process characterized by:

• A. A heavy nucleus capturing a neutron and releasing energy
• B. The fusion of two nuclei to form a heavier element
• C. A lighter element emitting an alpha particle through radioactive decay
• D. An electron being absorbed by the nucleus with the release of a gamma ray

Correct answer: A

Rationale: Nuclear fission is a process characterized by a heavy nucleus capturing a neutron and splitting into smaller nuclei, releasing a significant amount of energy in the form of heat and radiation. This differs from nuclear fusion, which involves the merging of two lighter nuclei to form a heavier element. The emission of an alpha particle by a lighter element is a form of radioactive decay, not fission. Absorption of an electron by the nucleus with the release of a gamma ray is not representative of fission reactions. Therefore, option A correctly describes the process of nuclear fission.

4. Which technology allows scientists to directly edit the human genome?

• A. Polymerase Chain Reaction (PCR)
• B. Gel electrophoresis
• C. DNA sequencing
• D. CRISPR-Cas9

Correct answer: D

Rationale: Rationale: A) Polymerase Chain Reaction (PCR) is a technique used to amplify a specific segment of DNA through repeated cycles of heating and cooling. PCR is not used for directly editing the human genome. B) Gel electrophoresis is a technique used to separate DNA fragments based on size. It is not used for directly editing the human genome. C) DNA sequencing is a method used to determine the precise order of nucleotides in a DNA molecule. While DNA sequencing is important for understanding genetic information, it is not used for directly editing the human genome. D) CRISPR-Cas9 is a technology that allows scientists to make precise changes to the DNA of living organisms, including the human genome. CRISPR-Cas9 works by guiding the Cas9 enzyme to a specific location in the genome where it can make targeted cuts or edits. This technology has revolutionized genetic research and has the potential for applications

5. Action potentials, the all-or-nothing electrical signals traveling along neurons, are generated by the movement of:

• A. Glucose
• B. Sodium and potassium ions
• C. Neurotransmitters
• D. Myelin

Correct answer: B

Rationale: The correct answer is B: Sodium and potassium ions. Action potentials are generated by the movement of sodium and potassium ions across the neuronal membrane. During depolarization, sodium ions rush into the cell, causing a change in electrical charge. This influx of positive ions triggers the opening of voltage-gated potassium channels, allowing potassium ions to exit the cell during repolarization. Glucose is a source of energy for cells but does not directly generate action potentials. Neurotransmitters are chemical messengers released at synapses, while myelin is a fatty substance that insulates axons, speeding up the conduction of action potentials but not directly generating them.

6. Homologous structures are similar structures in different organisms that have a common evolutionary origin. An example is:

• A. Butterfly wings and bird wings (analogous structures with different origins)
• B. The arm of a human, the wing of a bat, and the flipper of a whale
• C. The eyes of an octopus and a human (convergent evolution with different origins)
• D. The stinger of a bee and the barb of a cactus (unrelated structures)

Correct answer: B

Rationale: Rationale: Homologous structures are similar structures found in different organisms that share a common evolutionary origin. In this case, the arm of a human, the wing of a bat, and the flipper of a whale are all examples of homologous structures. Despite serving different functions in these organisms, they share a common underlying structure due to their evolutionary relationship. These structures are evidence of a shared ancestry and are modified over time to suit the specific needs of each species. Option A (Butterfly wings and bird wings) refers to analogous structures, which have similar functions but different evolutionary origins. Option C (The eyes of an octopus and a human) describes convergent evolution, where similar traits evolve independently in different species due to similar environmental pressures. Option D (The stinger of a bee and the barb of a cactus) refers to unrelated

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