Nursing Elites

1. A car is moving in a circle at a constant speed. Which of the following is NOT true about its motion?

• A. It has a constant centripetal acceleration
• B. Its tangential velocity remains constant
• C. It experiences a force directed towards the center of the circle
• D. It covers the same distance in equal time intervals along its circular path

Correct answer: B

Rationale: In circular motion at a constant speed, the car has a constant centripetal acceleration (choice A), experiences a force directed towards the center of the circle (choice C), and covers the same distance in equal time intervals along its circular path (choice D). However, the tangential velocity of an object in circular motion at a constant speed changes continuously as it moves around the circle, so it is not constant (choice B). The change in tangential velocity allows the car to maintain its motion in a circular path despite moving at a constant speed. Choice A is incorrect because centripetal acceleration is indeed present to keep the car moving in a circular path. Choice C is incorrect as a force towards the center is required to keep the car in circular motion. Choice D is incorrect because the car covers equal distances in equal time intervals to maintain its circular trajectory.

2. During embryonic development, most vertebrates exhibit structures called pharyngeal pouches. These pouches eventually develop into different structures in various vertebrate groups, such as the human jaw and inner ear. Pharyngeal pouches are an example of:

• A. Analogous structures with different evolutionary origins but similar functions
• B. Homologous structures with a common evolutionary origin but diverse functions
• C. Vestigial structures that no longer serve a vital function in some organisms
• D. Atavisms, the reappearance of a trait absent in recent generations

Correct answer: B

Rationale: Pharyngeal pouches in vertebrates are an example of homologous structures because they share a common evolutionary origin. Despite developing into different structures in various vertebrate groups, such as the jaw and inner ear in humans, these structures originated from the same ancestral feature. This concept of homology highlights the evolutionary relationship between different species and how structures can be modified over time to serve different functions while retaining a common origin. Choice A is incorrect because analogous structures have similar functions but different evolutionary origins, which does not apply to pharyngeal pouches. Choice C is incorrect as vestigial structures are remnants of features that were functional in ancestors but have reduced or lost their original function, which is not the case for pharyngeal pouches. Choice D is incorrect because atavisms refer to the reappearance of traits absent in recent generations, which is not the characteristic of pharyngeal pouches.

3. Which of the following brain structures is responsible for emotions, emotional behavior, and motivation?

• A. Amygdala
• B. Cerebellum
• C. Hypothalamus
• D. Pons

Correct answer: A

Rationale: The correct answer is the amygdala. The amygdala is a key brain structure involved in processing emotions, emotional behavior, and motivation. It plays a crucial role in fear responses, emotional memories, and social behaviors. The cerebellum (Choice B) is primarily responsible for coordination and balance, not emotions. The hypothalamus (Choice C) regulates basic survival functions like hunger, thirst, and body temperature, but it is not primarily responsible for emotions. The pons (Choice D) is involved in functions such as sleep, respiration, and bladder control, but it is not the main center for emotions, emotional behavior, or motivation.

4. What function do hydrophobic proteins often provide in the body?

• A. Digestive enzymes
• B. Provide structure
• C. Carry oxygen molecules
• D. Store energy

Correct answer: B

Rationale: Hydrophobic proteins are known for their ability to repel water and are often involved in providing structural support in cells and tissues. They help maintain the structural integrity and shape of cell membranes, organelles, and other cellular components. Choice A, digestive enzymes, typically consist of hydrophilic proteins that interact with water and substrates to facilitate digestion. Choice C, carrying oxygen molecules, is a function commonly associated with specific proteins like hemoglobin. Choice D, storing energy, is usually performed by proteins like enzymes involved in energy storage and release, such as glycogen phosphorylase.

5. In the reaction 2Na + 2H2O → 2NaOH + H2, what is the limiting reactant when 3 moles of sodium react with 2 moles of water?

• A. Na
• B. H2O
• C. NaOH
• D. H2

Correct answer: A

Rationale: The balanced chemical equation indicates that 2 moles of sodium react with 2 moles of water to yield 2 moles of sodium hydroxide and 1 mole of hydrogen gas. When 3 moles of sodium react with only 2 moles of water, sodium becomes the limiting reactant as it is present in excess compared to the available water molecules. This situation arises because not all sodium atoms can fully react with the limited amount of water, resulting in sodium being the limiting reactant in this specific case. Choice B (H2O), choice C (NaOH), and choice D (H2) are incorrect as they are not the limiting reactant in the given reaction scenario.

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