Nursing Elites

1. 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.

2. What is the term for a solution that contains the maximum amount of solute that can dissolve at a specific temperature and pressure?

• A. Saturated solution
• B. Unsaturated solution
• C. Dilute solution
• D. Concentrated solution

Correct answer: A

Rationale: A saturated solution is defined as a solution that has dissolved the maximum amount of solute possible at a specific temperature and pressure. In a saturated solution, any additional solute added will not dissolve, resulting in a visible precipitate. Choice B, unsaturated solution, refers to a solution where more solute can still be dissolved. Choices C and D, dilute solution and concentrated solution, do not specifically refer to the maximum amount of solute that can be dissolved at a given temperature and pressure, making them incorrect in this context.

3. Which of the following correctly matches a category of protein with a physiological example?

• A. Keratin is a structural protein
• B. Antigens are hormonal proteins
• C. Channel proteins are marker proteins
• D. Actin is a transport protein

Correct answer: A

Rationale: Keratin is indeed a type of structural protein found in the skin, hair, and nails of animals. It provides strength and protection, helping to maintain the overall structure of these tissues. The other choices are incorrect as antigens are not hormonal proteins but rather are involved in immune response, channel proteins are involved in facilitating the transport of ions or molecules across cell membranes, and actin is primarily involved in cell structure and movement, not as a transport protein.

4. What term describes the functional unit of a skeletal muscle responsible for muscle contraction?

• A. Myofibril
• B. Sarcomere
• C. Tendon
• D. Myoglobin

Correct answer: B

Rationale: The correct answer is B, 'Sarcomere.' The sarcomere is indeed the functional unit of a skeletal muscle responsible for muscle contraction. It is composed of actin and myosin filaments that interact to generate muscle contraction. Choice A, 'Myofibril,' is incorrect as myofibrils are composed of sarcomeres, not the functional units themselves. Choice C, 'Tendon,' is incorrect as tendons connect muscles to bones and do not directly participate in muscle contraction. Choice D, 'Myoglobin,' is incorrect as myoglobin is a protein that stores oxygen in muscle cells and is not directly involved in muscle contraction.

5. What is the function of the pleurae?

• A. To compartmentalize and lubricate the lungs
• B. To facilitate the flow of air
• C. To produce mucus
• D. To serve as the passageway for air

Correct answer: A

Rationale: The pleurae play a crucial role in compartmentalizing and lubricating the lungs. The pleura is a double-layered membrane that surrounds the lungs and lines the chest cavity. This double-layered structure reduces friction between the lungs and the chest wall during breathing movements, allowing smooth expansion and contraction of the lungs. Options B, C, and D are incorrect. Option B, 'To facilitate the flow of air,' is incorrect because while the pleurae are involved in the respiratory process, their primary function is not to directly facilitate the flow of air. Option C, 'To produce mucus,' is incorrect as the production of mucus is not a primary function of the pleurae. Option D, 'To serve as the passageway for air,' is incorrect as the passageway for air refers to the air passages like the trachea and bronchi, not the pleurae. Therefore, option A is correct as it accurately describes the function of the pleurae.

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