Nursing Elites

1. The fatty sheath that insulates some nerve fibers and speeds up signal transmission is called the:

• A. Myelin sheath
• B. Dura mater
• C. Pia mater
• D. Arachnoid mater

Correct answer: A

Rationale: The correct answer is A: Myelin sheath. The myelin sheath is a fatty layer that surrounds and insulates certain nerve fibers. It acts as an electrical insulator, speeding up the transmission of nerve impulses along the axon. This insulation helps to prevent signal loss or interference, allowing for faster and more efficient communication between neurons. The other options, B: Dura mater, C: Pia mater, and D: Arachnoid mater, are all layers of the meninges that protect the brain and spinal cord, but they do not play a role in insulating nerve fibers for signal transmission like the myelin sheath does.

2. What property of a substance refers to its ability to be drawn into thin wires without breaking?

• A. Malleability
• B. Viscosity
• C. Ductility
• D. Conductivity

Correct answer: c

Rationale: Ductility is the property that describes a substance's ability to be drawn into thin wires without breaking.

3. When water boils, it changes from a liquid to a gas. This is an example of a:

• A. Chemical reaction
• B. Physical change
• C. Nuclear reaction
• D. Biological process

Correct answer: B

Rationale: Physical change - Boiling water involves a change in state, not the chemical composition of the molecules. Chemical reactions involve breaking and forming new bonds, which is not the case here.

4. Which property of matter remains constant regardless of changes in gravity?

• A. Mass
• B. Weight
• C. Volume
• D. Density

Correct answer: A

Rationale: Mass is a measure of the amount of matter in an object and remains constant regardless of changes in gravity. Weight, on the other hand, is the force of gravity acting on an object's mass and can vary depending on the strength of gravity. Volume is the amount of space an object occupies, which can change depending on the environment, and density is the mass of an object per unit volume, which can also change with variations in gravity.

5. Which respiratory structure is responsible for the production of mucus to trap particles and for the movement of cilia to sweep mucus and trapped particles out of the respiratory tract?

• A. Trachea
• B. Larynx
• C. Bronchi
• D. Respiratory epithelium

Correct answer: D

Rationale: The correct answer is D: Respiratory epithelium. The respiratory epithelium is a specialized tissue lining the respiratory tract that produces mucus to trap particles and contains cilia that beat in a coordinated manner to move the mucus and trapped particles out of the respiratory tract. The trachea, larynx, and bronchi are all structures within the respiratory system, but they do not directly produce mucus or have cilia for sweeping particles. Therefore, the respiratory epithelium is the specific structure responsible for these functions.

6. The neutral theory of molecular evolution proposes that:

• A. Most mutations in DNA are selectively neutral and do not affect an organism's fitness.
• B. All mutations are beneficial and contribute to the adaptation of a population.
• C. The rate of evolution is primarily driven by strong directional selection pressures.
• D. Genetic drift plays a negligible role in shaping genetic variation within populations.

Correct answer: A

Rationale: Rationale: A) The neutral theory of molecular evolution, proposed by Motoo Kimura in the 1960s, suggests that the majority of mutations that occur in DNA are selectively neutral, meaning they do not have a significant impact on an organism's fitness. These neutral mutations are not subject to natural selection and are allowed to accumulate in populations over time. This theory helps explain the high levels of genetic variation observed within populations. B) Option B is incorrect because not all mutations are beneficial. Mutations can be neutral, harmful, or beneficial, and the neutral theory specifically focuses on the idea that many mutations are neutral in their effects. C) Option C is incorrect because the neutral theory suggests that evolution is not primarily driven by strong directional selection pressures. Instead, it emphasizes the role of genetic drift and the accumulation of neutral mutations in shaping genetic variation. D) Option D is incorrect because

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