Nursing Elites

1. What is the feedback mechanism in the endocrine system that helps maintain hormone balance?

• A. Positive feedback, where a hormone stimulates its own release
• B. Negative feedback, where a hormone suppresses its own release
• C. Cascade effect, where one hormone triggers the release of another
• D. Dual hormone system, where two hormones work together

Correct answer: B

Rationale: In the endocrine system, negative feedback is the mechanism by which hormone levels are regulated. When hormone levels reach a certain threshold, they signal the body to stop producing more of that hormone, thus maintaining a balance. Negative feedback (option B) is the correct answer as it helps in preventing overproduction of hormones by suppressing their own release. Positive feedback (option A) would lead to an excessive production of hormones, disrupting the balance. The cascade effect (option C) involves one hormone triggering the release of another but does not directly regulate hormone levels. The dual hormone system (option D) refers to two hormones working together but does not specifically address the feedback mechanism for maintaining hormone balance.

2. Which of the following units is used to express concentration as a mass of solute per unit volume of solution?

• A. Molality (m)
• B. Molarity (M)
• C. Weight percent (%)
• D. Parts per million (ppm)

Correct answer: A

Rationale: Molality (m) is the unit used to express concentration as a mass of solute per unit volume of solution. It is calculated by dividing the mass of solute in grams by the mass of the solvent in kilograms. Molality is preferred over molarity when there are large temperature variations as it is temperature-independent, making it a more accurate measure of concentration. Molarity (B) is the unit used to express concentration as moles of solute per liter of solution, weight percent (C) is the mass of solute per 100 parts of the total mass of the solution, and parts per million (D) is used to express very small concentrations where 1 ppm is equivalent to 1 mg of solute per liter of solution.

3. A rocket blasts off from Earth. What is the main force propelling the rocket upwards?

• A. Gravitational force
• B. Air resistance
• C. Thrust from the rocket engine
• D. Normal force from the launchpad

Correct answer: C

Rationale: The main force propelling the rocket upwards is the thrust from the rocket engine. Thrust is the force produced by the rocket engine pushing exhaust gases in the opposite direction, following Newton's third law of motion (action and reaction). This thrust overcomes the force of gravity and allows the rocket to lift off and move upwards. Choice A, gravitational force, is incorrect as gravity pulls objects towards the Earth, and in this case, the rocket is moving against gravity. Choice B, air resistance, is incorrect because it opposes the motion of the rocket and is more relevant during descent rather than ascent. Choice D, normal force from the launchpad, is incorrect as this force acts perpendicular to the surface and does not propel the rocket upwards.

4. In the reaction 4Al + 3O2 → 2Al2O3, what is the mole ratio of aluminum to oxygen?

• A. 4:3
• B. 2:3
• C. 3:2
• D. 3:4

Correct answer: A

Rationale: The balanced chemical equation shows that 4 moles of aluminum react with 3 moles of oxygen to produce 2 moles of aluminum oxide. Therefore, the mole ratio of aluminum to oxygen is 4:3. Choice B (2:3) is incorrect because it does not reflect the correct ratio based on the balanced equation. Choice C (3:2) and Choice D (3:4) are also incorrect as they do not represent the correct mole ratio of aluminum to oxygen according to the balanced chemical equation.

5. Which of the following is a dense, interconnected mass of nerve cells located outside the central nervous system?

• A. ganglion
• B. dendrite
• C. cranial nerve
• D. pons

Correct answer: A

Rationale: A ganglion is a dense, interconnected mass of nerve cells located outside the central nervous system. Ganglia serve as relay points where nerve cells communicate and integrate signals. They are found along peripheral nerves, processing sensory information and coordinating motor responses. Choice B, dendrite, refers to a part of a neuron that receives signals, not a mass of nerve cells. Choice C, cranial nerve, is a bundle of nerves that emerge from the brain, not a mass of nerve cells. Choice D, pons, is a part of the brainstem, which is within the central nervous system, not located outside of it.

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