Nursing Elites

1. Which of the following is an example of a polymer?

• A. Methane
• B. Ethanol
• C. Polyethylene
• D. Acetic acid

Correct answer: C

Rationale: The correct answer is C, Polyethylene. Polyethylene is a polymer composed of a large number of repeating ethylene units linked together, forming a long-chain molecule, characteristic of polymers. Methane, ethanol, and acetic acid are small organic molecules that do not demonstrate the repeating unit structure typical of polymers. Therefore, they are not examples of polymers.

2. How do spindle fiber dynamics and microtubule attachment regulate cell cycle checkpoints?

• A. Misaligned chromosomes fail to attach to microtubules, triggering a delay in anaphase onset.
• B. The presence of unattached kinetochores on the centromeres sends a signal to pause cell cycle progression.
• C. Microtubule instability and rapid depolymerization lead to the activation of checkpoint proteins.
• D. All of the above.

Correct answer: D

Rationale: A) Misaligned chromosomes fail to attach to microtubules, triggering a delay in anaphase onset: Proper attachment of chromosomes to spindle fibers is essential for accurate segregation of genetic material during cell division. Misaligned chromosomes that fail to attach to microtubules can lead to delays in anaphase onset, allowing the cell to correct errors before proceeding with division. B) The presence of unattached kinetochores on the centromeres sends a signal to pause cell cycle progression: Kinetochores at the centromeres help attach chromosomes to spindle fibers. When kinetochores are unattached or improperly attached to microtubules, they signal the cell to pause cell cycle progression, ensuring proper chromosome alignment before division. C) Microtubule instability and rapid depolymerization lead to the activation of checkpoint proteins: While microtubule dynamics are crucial for cell division, microtubule instability and rapid depolymerization can disrupt chromosome attachment. However, this mechanism is not directly related to the activation of cell cycle checkpoint proteins, making this statement incorrect. Therefore, choices A and B accurately describe how spindle fiber dynamics and microtubule attachment regulate cell cycle checkpoints, making option D the correct answer.

3. What is the primary function of the lymphatic system?

• A. Transporting oxygen and nutrients to cells
• B. Carrying waste products away from tissues
• C. Regulating body temperature
• D. Producing red blood cells

Correct answer: B

Rationale: The primary function of the lymphatic system is to carry waste products away from tissues. Lymphatic vessels collect excess fluid, waste materials, and toxins from the body's tissues and transport them to the bloodstream for elimination. Choice A is incorrect because transporting oxygen and nutrients to cells is mainly the function of the circulatory system. Choice C is incorrect as regulating body temperature is primarily done by the body's thermoregulatory mechanisms. Choice D is incorrect because the production of red blood cells occurs in the bone marrow, not in the lymphatic system.

4. The fossil record shows that dinosaurs with feathers existed millions of years before birds. This is evidence for

• A. Convergent evolution (unrelated organisms evolving similar traits)
• B. Divergent evolution (related organisms evolving different traits)
• C. Coevolution (two species influencing each other's evolution)
• D. The extinction of dinosaurs due to an asteroid impact

Correct answer: A

Rationale: The fossil record indicates that dinosaurs had feathers before birds, suggesting convergent evolution. Convergent evolution occurs when unrelated organisms independently evolve similar traits to adapt to similar environmental pressures. In this case, both dinosaurs and birds developed feathers for flight or insulation purposes, even though they are not closely related. This evidence supports the concept of convergent evolution rather than divergent evolution, coevolution, or the extinction of dinosaurs due to an asteroid impact. Therefore, the correct answer is A, as it best explains the scenario where dinosaurs with feathers existed before birds, showcasing the concept of unrelated organisms evolving similar traits independently.

5. What is the term for the process of bone formation and breakdown?

• A. Ossification
• B. Resorption
• C. Remodeling
• D. All of the above

Correct answer: C

Rationale: The correct term for the process of bone formation and breakdown is remodeling. Ossification specifically refers to bone formation, while resorption pertains to bone breakdown. Remodeling encompasses both processes, as it involves the continuous cycle of bone formation and resorption to maintain bone strength and structure. Choice A, 'Ossification,' is incorrect as it only refers to bone formation. Choice B, 'Resorption,' is incorrect as it only refers to bone breakdown. Choice D, 'All of the above,' is incorrect as it includes terms that are not comprehensive of both bone formation and breakdown.

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