Nursing Elites

1. What is the function of valves in arteries?

• A. To maintain high blood pressure for the proper diffusion of nutrients in capillaries.
• B. To prevent backflow of blood due to high pressure away from the heart.
• C. As a vestigial trait from evolution, like the appendix, that serves no purpose.
• D. Valves are absent in arteries but present in veins.

Correct answer: B

Rationale: Valves in arteries serve the crucial function of preventing backflow of blood. Arteries carry blood at high pressure away from the heart, and the valves ensure that blood flows in one direction, towards the capillaries, to maintain efficient circulation. Without these valves, there would be a risk of blood flowing backward, compromising the effectiveness of blood circulation in the body. Choices A, C, and D are incorrect. Choice A incorrectly suggests that valves maintain high blood pressure for nutrient diffusion in capillaries, which is not their function. Choice C inaccurately compares valves to vestigial traits, like the appendix, implying they serve no purpose, which is untrue. Choice D is incorrect as valves are indeed present in arteries to regulate blood flow, not just in veins.

2. Which part of the digestive system is primarily responsible for absorbing nutrients?

• A. Stomach
• B. Small intestine
• C. Esophagus
• D. Large intestine

Correct answer: B

Rationale: The small intestine is the primary site for nutrient absorption in the digestive system. It is lined with specialized cells that facilitate the absorption of nutrients such as carbohydrates, proteins, fats, vitamins, and minerals into the bloodstream for distribution throughout the body. While the stomach plays a role in digestion by breaking down food with acid and enzymes, the actual absorption of nutrients occurs mainly in the small intestine. The esophagus is responsible for transporting food from the mouth to the stomach, but it does not absorb nutrients. The large intestine primarily absorbs water and electrolytes, not nutrients.

3. Iron is a transition metal, which means it often forms a cation with a charge of what?

• A. 2- or 3-
• B. 1-
• C. 2+ or 3+
• D. 1+

Correct answer: C

Rationale: The correct answer is C: 2+ or 3+. Transition metals, like iron, are known for their ability to exhibit variable oxidation states. This characteristic allows them to form cations with charges such as 2+ or 3+. Specifically, iron can form cations with these charges due to the varying electron configurations in its d-orbitals. The other choices are incorrect because transition metals typically form positively charged cations, not negatively charged ones. Additionally, while iron can form cations with charges of 2+ or 3+, it does not commonly form cations with charges of 1- or 1+. Transition metal cations play a crucial role in forming coordination complexes with ligands, highlighting their importance in various chemical reactions.

4. Which level of protein structure is defined by the folds and coils of the protein's polypeptide backbone?

• A. Primary
• B. Secondary
• C. Tertiary
• D. Quaternary

Correct answer: B

Rationale: The correct answer is B: Secondary. The secondary structure of a protein is defined by the folds and coils of the protein's polypeptide backbone. This level of structure is characterized by the formation of alpha helices and beta sheets, which are stabilized by hydrogen bonds between amino acids along the polypeptide chain. Choice A, Primary, refers to the linear sequence of amino acids in the protein. Choice C, Tertiary, involves the 3D folding of the entire polypeptide chain. Choice D, Quaternary, pertains to the arrangement of multiple polypeptide subunits in a protein complex.

5. In a chemical reaction, the total amount of:

• A. Matter remains the same
• B. Matter increases
• C. Matter decreases
• D. Energy remains the same

Correct answer: A

Rationale: The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction, only rearranged. This principle implies that the total amount of matter before and after a chemical reaction must remain constant, supporting the correct answer choice A. Choice B is incorrect because the total amount of matter does not increase in a chemical reaction; it is conserved. Choice C is incorrect as the total amount of matter does not decrease in a chemical reaction; it is conserved. Choice D is incorrect since the conservation of energy is a different principle and does not directly relate to the total amount of matter in a chemical reaction.

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