Nursing Elites

1. Which of the following is an example of a nonpolar solvent?

• A. Water
• B. Ethanol
• C. Acetone
• D. Hydrochloric acid

Correct answer: B

Rationale: - Water (option A) is a polar solvent due to its uneven distribution of charge, with the oxygen atom being partially negative and the hydrogen atoms being partially positive. - Ethanol (option B) is a nonpolar solvent because it has a symmetrical molecular structure that does not result in significant charge separation. - Acetone (option C) is a polar solvent as it contains a carbonyl group that results in a partial negative charge on the oxygen atom. - Hydrochloric acid (option D) is a polar solvent due to the presence of the highly electronegative chlorine atom, which results in a partial negative charge.

2. What is the structure of DNA?

• A. Single-stranded, linear
• B. Double-stranded, linear
• C. Double-stranded, helix
• D. Single-stranded, helix

Correct answer: C

Rationale: The correct answer is C: Double-stranded, helix. DNA is structured as a double helix formed by two strands of nucleotides. The nucleotides are paired with complementary bases (A-T and C-G) in the center, held together by hydrogen bonds. This double-stranded helical structure is a fundamental characteristic of DNA and essential for its function in storing genetic information. Choices A, B, and D are incorrect because DNA is not single-stranded; it consists of two strands that run antiparallel to each other and are connected via hydrogen bonds. Additionally, DNA does not have a linear structure but rather a helical one, providing stability and protection to the genetic information it carries.

3. 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.

4. What is the name of the long bone found in the upper arm?

• A. Femur
• B. Tibia
• C. Humerus
• D. Radius

Correct answer: C

Rationale: The correct answer is the humerus. The humerus is the long bone located in the upper arm, between the shoulder and elbow. Option A, Femur, is incorrect as it is the long bone found in the thigh. Option B, Tibia, is incorrect as it is a long bone found in the lower leg. Option D, Radius, is incorrect as it is a bone located in the forearm, not the upper arm.

5. Which of the following terms refers to a muscle twitch, a single forceful contraction of a muscle fiber?

• A. Tetanus
• B. Tremor
• C. Fasciculation
• D. Rigidity

Correct answer: C

Rationale: The correct term for a muscle twitch, a single forceful contraction of a muscle fiber, is 'Fasciculation' (choice C). Fasciculation specifically describes this phenomenon. 'Tetanus' (choice A) refers to sustained muscle contraction, 'Tremor' (choice B) indicates a shaky or quivering movement, and 'Rigidity' (choice D) denotes stiffness or inflexibility in muscles. Therefore, choices A, B, and D are incorrect in the context of a single forceful contraction of a muscle fiber.

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