Nursing Elites

1. Why is biodiversity important for healthy ecosystems?

• A. Increases stability and resilience to disturbances
• B. Provides stability and resilience to disturbances
• C. Slows down nutrient cycling
• D. Reduces the number of decomposers

Correct answer: B

Rationale: Biodiversity refers to the variety of living organisms in a particular area. A diverse ecosystem is better able to withstand and recover from disturbances such as natural disasters, climate change, or human impacts. This is because different species play unique roles in the ecosystem, and a higher level of biodiversity means there are more species available to fulfill these roles. For example, if one species is negatively affected by a disturbance, other species may be able to compensate for its loss, maintaining the overall functioning of the ecosystem. Therefore, biodiversity provides stability and resilience to disturbances, making ecosystems healthier and more sustainable. Choice A is incorrect because biodiversity doesn't increase competition for resources but rather helps in maintaining a balance within the ecosystem. Choice C is incorrect as biodiversity does not slow down nutrient cycling; in fact, it enhances nutrient cycling by ensuring a variety of species involved in the process. Choice D is incorrect as biodiversity does not reduce the number of decomposers but instead supports a diverse community of decomposers that are essential for nutrient recycling in ecosystems.

2. Which of the following lists the structures found beneath the rib in descending order?

• A. Nerve → Artery → Vein
• B. Vein → Nerve → Artery
• C. Vein → Artery → Nerve
• D. Artery → Nerve → Vein

Correct answer: C

Rationale: The correct order of structures found beneath the rib in descending order is Vein → Artery → Nerve. This sequence is important to remember for medical procedures like inserting a chest tube to ensure precision and avoid complications. Choice A is incorrect because the nerve is not typically the structure closest to the rib. Choice B is incorrect as the vein is usually closer to the rib than the nerve. Choice D is incorrect as the artery is usually closer to the rib than the nerve.

3. Isotopes are variants of a single element that differ in:

• A. Having the same number of protons but varying numbers of neutrons
• B. Having the same number of neutrons but varying numbers of protons
• C. Having the same mass but different atomic numbers
• D. None of the above

Correct answer: A

Rationale: Isotopes are variants of a single element that have the same number of protons, the defining characteristic of an element. They differ in the number of neutrons they possess, leading to isotopes having different atomic masses while retaining the same chemical properties. Choice B is incorrect because isotopes have the same number of neutrons and differ in the number of protons. Choice C is incorrect because isotopes have different masses due to varying numbers of neutrons, not different atomic numbers. Choice D is incorrect as isotopes do differ in the number of neutrons they possess.

4. Which structure in the lungs is the site of gas exchange?

• A. Trachea
• B. Alveoli
• C. Bronchioles
• D. Diaphragm

Correct answer: B

Rationale: The correct answer is B: Alveoli. Alveoli are tiny air sacs in the lungs where gas exchange occurs. Oxygen from inhaled air diffuses into the bloodstream, while carbon dioxide from the blood is released into the alveoli to be exhaled. The trachea (Choice A) is the windpipe that carries air to and from the lungs, but it is not involved in gas exchange. Bronchioles (Choice C) are small air passages within the lungs that branch off from the bronchi, leading air to the alveoli but not directly involved in gas exchange. The diaphragm (Choice D) is a muscle below the lungs that helps in breathing by expanding and contracting the chest cavity, but it is not the site of gas exchange.

5. During which phase of meiosis do chiasmata structures form?

• A. Prophase I
• B. Prophase II
• C. Metaphase I
• D. Metaphase II

Correct answer: A

Rationale: Chiasmata structures, where crossing over occurs, form during Prophase I of meiosis. This phase is characterized by homologous chromosomes pairing up and crossing over, leading to the exchange of genetic material between non-sister chromatids. Chiasmata are visible points of contact where genetic material has been exchanged, and they play a critical role in genetic diversity. Prophase II is the phase where chromosomes condense again in the second meiotic division, but chiasmata formation occurs in Prophase I. Metaphase I is the phase where homologous chromosomes align at the metaphase plate, not where chiasmata form. Metaphase II is the phase where replicated chromosomes align at the metaphase plate in the second meiotic division, but chiasmata formation occurs earlier in Prophase I.

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