Nursing Elites

1. Which of the following best describes a chemical change?

• A. Melting ice to form water
• B. Dissolving sugar in water
• C. Burning wood to produce ash
• D. Crushing a can to reduce its size

Correct answer: c

Rationale: Chemical changes involve the formation of new substances with different chemical properties. Burning wood involves a chemical reaction where wood undergoes combustion, breaking down its chemical structure to produce new substances like ash and gases.

2. Myelin sheath, a fatty substance, insulates nerve fibers. What type of tissue is the myelin sheath derived from?

• A. Epithelial tissue
• B. Muscle tissue
• C. Nervous tissue (glial cells)
• D. Connective tissue

Correct answer: C

Rationale: The myelin sheath is derived from nervous tissue, specifically from glial cells, which are non-neuronal cells that support and protect neurons in the nervous system. Glial cells, such as Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system, produce the myelin sheath to insulate nerve fibers and enhance the speed of nerve impulse conduction. Epithelial tissue forms the protective covering of internal and external surfaces, muscle tissue is responsible for movement, and connective tissue provides support and structure to the body. Therefore, the correct answer is C: Nervous tissue (glial cells).

3. 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.

4. A baseball is thrown into the air. At the peak of its trajectory, which of the following forces is acting on the ball?

• A. Only gravitational force
• B. Only the force of air resistance
• C. Both gravitational force and the force of air resistance
• D. Neither gravitational force nor the force of air resistance

Correct answer: A

Rationale: At the peak, the ball momentarily stops moving upwards. Its inertia keeps it moving horizontally, but there is no force propelling it upwards except for gravity pulling it down.

5. How does lymph move through the lymphatic vessels?

• A. By the pumping action of the heart
• B. Due to muscle contractions and breathing movements
• C. Through one-way valves within the vessels
• D. All of the above

Correct answer: D

Rationale: The correct answer is D: "All of the above." Lymph, a clear fluid that carries immune cells and waste products, moves through the lymphatic vessels by multiple mechanisms. While the pumping action of the heart plays a minor role, the primary driving forces are muscle contractions and breathing movements that squeeze the vessels. Additionally, lymphatic vessels contain one-way valves that prevent the backward flow of lymph, ensuring that it moves in the right direction. Therefore, all of the options provided contribute to the movement of lymph through the lymphatic system.

6. Molecular clocks utilize the accumulation of mutations in DNA sequences to estimate the evolutionary divergence time between species. This method relies on the assumption that:

• A. The rate of mutation is constant across all genes and all species.
• B. Species with more morphological similarities diverged more recently.
• C. Mutations are always beneficial and contribute to increased fitness.
• D. The fossil record provides the most accurate estimates of evolutionary relationships.

Correct answer: A

Rationale: Rationale: A molecular clock is a method used to estimate the time of divergence between species by measuring the accumulation of mutations in DNA sequences. This method relies on the assumption that mutations occur at a relatively constant rate over time. If the rate of mutation were not constant, it would be challenging to accurately estimate the evolutionary divergence time between species. Therefore, option A is the most appropriate choice as it aligns with the fundamental principle underlying the molecular clock hypothesis. Option B is incorrect because the assumption that species with more morphological similarities diverged more recently does not directly relate to the concept of molecular clocks and the accumulation of mutations in DNA sequences. Option C is incorrect because mutations are not always beneficial and do not always contribute to increased fitness. Mutations can be neutral or deleterious as well, and their accumulation is what is used to estimate evolutionary di

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