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: The correct answer is B: Negative feedback, where a hormone suppresses its own release. In the endocrine system, negative feedback is a crucial mechanism that helps maintain hormone balance. When hormone levels rise, they signal the body to decrease further hormone production, preventing an excess. This ensures that hormone levels stay within a narrow range, promoting stability and homeostasis. Positive feedback (option A) would lead to an amplification of hormone release, which is not ideal for maintaining balance. Cascade effect (option C) involves a sequential activation of hormones but does not directly regulate hormone levels. Dual hormone system (option D) refers to two hormones working together but doesn't specifically address the feedback mechanism for maintaining hormone balance.

2. What is the primary hormone released by the parathyroid glands?

• A. Insulin
• B. Calcitonin
• C. Parathyroid hormone (PTH)
• D. Thyroxine

Correct answer: C

Rationale: The primary hormone released by the parathyroid glands is Parathyroid hormone (PTH), which plays a crucial role in regulating calcium levels in the body. Insulin is produced by the pancreas to regulate blood sugar levels and is unrelated to the parathyroid glands. Calcitonin is produced by the thyroid gland and helps regulate calcium levels but is not the primary hormone released by the parathyroid glands. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism and is also not released by the parathyroid glands. Therefore, the correct answer is C: Parathyroid hormone (PTH).

3. The phenomenon responsible for the creation of rainbows is:

• A. Reflection only
• B. Diffraction
• C. Refraction and reflection
• D. Polarization

Correct answer: C

Rationale: The correct answer is C: Refraction and reflection. Rainbows are formed when sunlight is refracted and reflected inside raindrops. The sunlight entering the raindrop is refracted, then internally reflected off the back surface of the droplet, and finally refracted again as it exits the droplet. This dispersion of light causes the separation of colors we see in a rainbow. Reflection alone (option A) does not account for the formation of rainbows. Diffraction (option B) is the bending of light around obstacles, not the main mechanism behind rainbows. Polarization (option D) refers to the orientation of light waves, which is not the primary process involved in creating rainbows.

4. Vaccines work by:

• A. Directly killing pathogens
• B. Introducing weakened or inactive versions of pathogens to trigger immune response
• C. Stimulating production of specific antibodies immediately
• D. None of the above

Correct answer: B

Rationale: The correct answer is B: Introducing weakened or inactive versions of pathogens to trigger an immune response. Vaccines work by exposing the immune system to a harmless version of a pathogen, which allows the body to recognize and develop a defense against the pathogen without causing illness. This process stimulates the immune system to produce memory cells that can quickly recognize and attack the pathogen if encountered in the future. Vaccines do not directly kill pathogens (option A) or immediately stimulate the production of specific antibodies (option C). Therefore, option B is the most accurate description of how vaccines work.

5. Which of the following factors does NOT affect the rate of dissolution of a solute in a solvent?

• A. Temperature
• B. Pressure
• C. Surface area
• D. Particle size

Correct answer: B

Rationale: Pressure does not affect the rate of dissolution of a solute in a solvent. The factors that do affect the rate of dissolution include temperature, surface area, and particle size. Temperature generally increases the rate of dissolution as it provides more energy for the solute particles to break apart and mix with the solvent. Increasing the surface area of the solute by grinding it into smaller particles or increasing its contact area with the solvent can also speed up dissolution. Similarly, reducing the particle size of the solute can increase the rate of dissolution by providing more surface area for interaction with the solvent.

6. What is the scientific unit used to measure the radioactivity of a substance?

• A. Becquerel (Bq)
• B. Joule (J)
• C. Newton (N)
• D. Kelvin (K)

Correct answer: A

Rationale: Becquerel measures the number of nuclear decays per second in a radioactive sample.

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