Nursing Elites

1. Which term describes the quantity of matter in an object and is measured in kilograms or grams?

• A. Weight
• B. Mass
• C. Volume
• D. Density

Correct answer: B

Rationale: Mass is the quantity of matter in an object and is commonly measured in kilograms or grams. It is a fundamental property of matter and remains constant regardless of the object's location. Weight, in contrast, refers to the force of gravity acting on an object and is measured in newtons. Volume represents the amount of space an object occupies and is typically measured in cubic units like cubic meters or cubic centimeters. Density, on the other hand, is the mass of an object per unit volume, and its unit is, for example, kilograms per cubic meter. Therefore, the correct answer is 'Mass' as it specifically describes the quantity of matter in an object, regardless of the gravitational pull on it. 'Weight,' 'Volume,' and 'Density' do not directly represent the quantity of matter in an object but rather different properties related to it.

2. What are the differences between RNA and DNA?

• A. Both have the same structure and function.
• B. RNA is single-stranded, while DNA is double-stranded.
• C. RNA contains ribose sugar, while DNA contains deoxyribose sugar.
• D. RNA has adenine and guanine, while DNA has thymine and cytosine.

Correct answer: B

Rationale: A) This statement is incorrect. RNA and DNA have different structures and functions. RNA is involved in protein synthesis and other cellular processes, while DNA stores genetic information. B) This statement is correct. RNA is typically single-stranded, while DNA is double-stranded, forming a double helix structure. C) This statement is correct. RNA contains ribose sugar in its backbone, while DNA contains deoxyribose sugar. D) This statement is incorrect. RNA contains adenine, guanine, cytosine, and uracil, while DNA contains adenine, guanine, cytosine, and thymine. Choice B is the correct answer as it accurately describes one of the key differences between RNA and DNA, emphasizing their structural disparity in terms of single-strandedness for RNA and double-strandedness for DNA. Choices A, C, and D contain inaccuracies regarding the structural and compositional distinctions between RNA and DNA, making them incorrect choices.

3. What macromolecules are proteins that speed up chemical reactions and act as biological catalysts?

• A. Lipids
• B. Enzymes
• C. Carbohydrates
• D. Nucleic acids

Correct answer: B

Rationale: Enzymes are proteins that act as biological catalysts, speeding up chemical reactions without being consumed in the process. Lipids, carbohydrates, and nucleic acids do not serve as proteins that function as catalysts; they have different biological roles. Lipids are primarily used for energy storage, structural components, and signaling molecules. Carbohydrates are mainly for energy storage and providing structural support. Nucleic acids are involved in genetic information storage and transfer. Therefore, the correct answer is B: Enzymes.

4. What are fingernails and toenails primarily made of?

• A. Collagen (Collagen is found in the dermis)
• B. Keratin
• C. Melanin (Melanin provides pigment, not structure)
• D. Sebum (Sebum is an oily substance)

Correct answer: B

Rationale: Fingernails and toenails are primarily made of a protein called keratin. Keratin is a tough, fibrous protein that provides structure and strength to nails, hair, and the outer layer of skin. Collagen, as mentioned, is found in the dermis and is not the primary component of nails. Melanin provides pigment to the skin and hair, not the structure of nails. Sebum is an oily substance produced by the skin's sebaceous glands and is not a structural component of nails.

5. Which valve prevents backflow into the atrium when the ventricles contract?

• A. Pulmonary valve
• B. Tricuspid valve
• C. Mitral valve
• D. Aortic valve

Correct answer: B

Rationale: The tricuspid valve (right atrioventricular valve) prevents backflow into the right atrium when the right ventricle contracts. This valve ensures that blood flows in the correct direction, preventing regurgitation into the atrium. The pulmonary valve is responsible for preventing backflow into the right ventricle from the pulmonary artery. The mitral valve prevents backflow into the left atrium, and the aortic valve prevents backflow into the left ventricle from the aorta. Therefore, the correct answer is the tricuspid valve as it specifically addresses the scenario of backflow into the atrium during ventricular contraction.

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