Nursing Elites

1. Homologous structures are similar structures in different organisms that have a common evolutionary origin. An example is:

• A. Butterfly wings and bird wings (analogous structures with different origins)
• B. The arm of a human, the wing of a bat, and the flipper of a whale
• C. The eyes of an octopus and a human (convergent evolution with different origins)
• D. The stinger of a bee and the barb of a cactus (unrelated structures)

Correct answer: B

Rationale: Homologous structures are similar structures found in different organisms that share a common evolutionary origin. The arm of a human, the wing of a bat, and the flipper of a whale are all examples of homologous structures. Despite serving different functions, they share a common underlying structure due to their evolutionary relationship, evidencing a shared ancestry. These structures are modified over time to suit the specific needs of each species. Option A (Butterfly wings and bird wings) refers to analogous structures with different origins. Option C (The eyes of an octopus and a human) describes convergent evolution where traits evolve independently. Option D (The stinger of a bee and the barb of a cactus) are unrelated structures.

2. What type of intermolecular force is responsible for the high surface tension of water?

• A. Hydrogen bonding
• B. London dispersion forces
• C. Ionic bonding
• D. Metallic bonding

Correct answer: A

Rationale: The high surface tension of water is primarily due to the strong hydrogen bonding between water molecules. Hydrogen bonding is a specific type of intermolecular force that occurs between a hydrogen atom covalently bonded to a highly electronegative atom, like oxygen in water, and another electronegative atom nearby. This unique interaction results in a strong attraction between water molecules at the surface, leading to the cohesive forces responsible for the high surface tension of water. Choices B, C, and D are incorrect because London dispersion forces, ionic bonding, and metallic bonding do not account for the high surface tension observed in water. London dispersion forces are relatively weaker intermolecular forces, while ionic and metallic bonding are types of intramolecular forces that do not directly contribute to the surface tension of water.

3. A rocket engine expels hot gases backwards. What principle explains the rocket's forward motion?

• A. Newton's first law of motion
• B. Newton's second law of motion
• C. Newton's third law of motion
• D. Law of conservation of energy

Correct answer: C

Rationale: Newton's third law of motion states that for every action, there is an equal and opposite reaction. In the case of a rocket engine expelling hot gases backwards, the action is the expulsion of gases, and the reaction is the forward motion of the rocket. The hot gases being expelled act as the action force, propelling the rocket in the opposite direction as the reaction force, resulting in the rocket's forward motion. Newton's first law of motion (Choice A) pertains to inertia, stating that an object in motion will stay in motion unless acted upon by an external force. Newton's second law of motion (Choice B) relates force, mass, and acceleration, which is not directly applicable to the scenario of a rocket engine propulsion. The law of conservation of energy (Choice D) is a fundamental principle stating that energy cannot be created or destroyed but can only be transformed, which does not directly explain the forward motion of the rocket in this context.

4. What units of measurement would a triple beam balance show?

• A. Liters
• B. Grams
• C. Meters
• D. Gallons

Correct answer: B

Rationale: A triple beam balance is used to measure mass, typically in grams. Liters, meters, and gallons are units of volume, length, and capacity, respectively, not typically measured using a triple beam balance. Therefore, the correct answer is grams. Choice A, Liters, is a unit of volume. Choice C, Meters, is a unit of length. Choice D, Gallons, is a unit of capacity. These units are not typically measured using a triple beam balance.

5. What is the pH value of a neutral solution?

• A. 0
• B. 7
• C. 14
• D. -7

Correct answer: B

Rationale: The pH scale measures the acidity or basicity of a solution. A pH of 7 is considered neutral, indicating that the concentration of hydrogen ions (H+) is equal to the concentration of hydroxide ions (OH-) in the solution. A pH ranging from 0 to 6.9 signifies acidity, while a pH from 7.1 to 14 signifies alkalinity. Therefore, a neutral solution has a pH value of 7. Choice A (0) represents a highly acidic solution, Choices C (14) and D (-7) are outside the valid pH range and do not correspond to a neutral solution.

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