Nursing Elites

1. Which property of a substance describes how much matter is packed into a given space?

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

Correct answer: D

Rationale: Density is the property of a substance that describes how much matter is packed into a given space. It is calculated by dividing the mass of the substance by its volume. Mass refers to the amount of matter in an object, volume is the amount of space an object occupies, and weight is the force of gravity acting on an object's mass. Density specifically relates to how tightly packed the particles of a substance are.

2. If you compare a 1 M solution of NaCl to a 1 M solution of glucose (C6H12O6) in water, which solution would have the higher boiling point?

• A. The NaCl solution
• B. The glucose solution
• C. They would have the same boiling point
• D. It depends on the temperature

Correct answer: A

Rationale: The correct answer is A. When a solute is added to a solvent, it raises the boiling point of the solution due to the phenomenon of boiling point elevation. In this case, NaCl is an ionic compound that dissociates into Na+ and Cl- ions in water, leading to more particles in solution compared to glucose, which remains as individual molecules. Since NaCl forms more particles, it causes a greater boiling point elevation, resulting in the NaCl solution having the higher boiling point. Glucose, being a non-electrolyte, does not dissociate and therefore does not contribute as many particles to the solution as NaCl does. Therefore, the NaCl solution would have the higher boiling point.

3. Unlike the circulatory system, the lymphatic system does not have a pump. 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.' Unlike the circulatory system which relies on the heart's pumping action, the lymphatic system lacks a central pump. Lymph moves through lymphatic vessels primarily due to muscle contractions and breathing movements that squeeze the vessels, helping propel the lymph forward. Additionally, one-way valves within the lymphatic vessels prevent the backward flow of lymph, ensuring it moves in the right direction. Therefore, all three mechanisms - heart pumping, muscle contractions, and one-way valves - work together to facilitate the movement of lymph through the lymphatic system.

4. The process by which two or more species reciprocally influence each other's evolution through selection pressures exerted on one another is called:

• A. Convergent evolution
• B. Divergent evolution
• C. Coevolution
• D. Coevolution

Correct answer: C

Rationale: Rationale: A) Convergent evolution refers to the process by which unrelated species evolve similar traits due to similar environmental pressures. This does not involve reciprocal influence between species. B) Divergent evolution refers to the process by which two or more related species become more dissimilar over time due to different selection pressures. This also does not involve reciprocal influence between species. C) Coevolution is the process by which two or more species reciprocally influence each other's evolution through selection pressures exerted on one another. This can lead to a close ecological relationship between the species, such as in predator-prey interactions or mutualistic relationships. D) This option is a duplicate of option C.

5. What is the myelin sheath and what does it do?

• A. A group of nerve cells that perform a specific function.
• B. A fatty substance that insulates some nerve fibers.
• C. A fluid-filled cavity within the brain.
• D. The junction between two neurons.

Correct answer: B

Rationale: The correct answer is B. The myelin sheath is a fatty substance that insulates some nerve fibers. It is essential for the proper functioning of the nervous system as it acts as an insulator, allowing for faster transmission of nerve impulses along the axon. Without the myelin sheath, nerve signals could be disrupted or weakened, leading to issues with movement, sensation, and other neurological functions. Options A, C, and D are incorrect as they do not accurately describe the myelin sheath or its function.

6. The tiny contractile units within muscle cells are called:

• A. Myocytes
• B. Myofibrils
• C. Sarcomeres
• D. Tendons

Correct answer: C

Rationale: The correct answer is C: Sarcomeres. Sarcomeres are the basic contractile units within muscle cells. They are made up of overlapping filaments of actin and myosin proteins, which slide past each other during muscle contraction, resulting in muscle movement. Myocytes (A) are muscle cells, myofibrils (B) are cylindrical structures within muscle fibers composed of sarcomeres, and tendons (D) are tough bands of connective tissue that connect muscle to bone. Therefore, sarcomeres are specifically responsible for muscle contraction within muscle cells.

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