Nursing Elites

1. When animals eat, insulin is released from the pancreas, stimulating glucose uptake by the liver. When glucose levels drop, the pancreas reduces insulin release. This is an example of which mechanism for maintaining homeostasis?

• A. Negative feedback.
• B. Positive feedback.
• C. Stress response.
• D. Parasympathetic regulation.

Correct answer: A

Rationale: This mechanism is an example of negative feedback. Negative feedback systems work to counteract changes in the body and maintain a stable internal environment (homeostasis). In this case, the release of insulin in response to high glucose levels is followed by a reduction in insulin release when glucose levels drop. This response helps regulate glucose levels and return them to a normal range, demonstrating the characteristic of negative feedback where the body's response opposes the initial stimulus to maintain equilibrium. Positive feedback would amplify the initial change rather than counteract it, so it is not the correct choice. Stress response and parasympathetic regulation are not directly involved in this glucose regulation process, making them incorrect choices.

2. Which of the following water-soluble vitamins is NOT synthesized in the large intestine?

• A. B6
• B. Biotin
• C. Pantothenic acid (Vitamin B5)
• D. Vitamin K

Correct answer: A

Rationale: The correct answer is A: B6. Vitamin B6 is not synthesized in the large intestine, while biotin, pantothenic acid (Vitamin B5), and Vitamin K can be synthesized by gut microflora. Biotin, B5, and K are examples of water-soluble vitamins that can be produced in the large intestine, but B6 needs to be obtained through dietary sources. Therefore, B6 is the correct answer as it is not synthesized within the large intestine, unlike the other options.

3. What is the main target organ for insulin, the hormone produced by the pancreas?

• A. Liver
• B. Kidneys
• C. Muscles
• D. Brain

Correct answer: C

Rationale: The main target organ for insulin is muscles. Insulin plays a crucial role in regulating glucose metabolism by promoting the uptake of glucose into muscle cells. This glucose can then be utilized for energy production or stored for later use. Therefore, muscles are the primary site where insulin exerts its effects on glucose uptake and utilization. The liver primarily responds to insulin by regulating glucose storage and release, but the main target for insulin-mediated glucose uptake is muscles. Kidneys are not a target organ for insulin action in glucose metabolism. The brain does not heavily rely on insulin for glucose uptake as it primarily uses glucose independently of insulin for energy production.

4. Which term is used to classify reactions that require light energy to proceed?

• A. Combustion reactions
• B. Endothermic reactions
• C. Photochemical reactions
• D. Double displacement reactions

Correct answer: C

Rationale: Reactions that require light energy to proceed are classified as photochemical reactions. Photochemical reactions involve the absorption of light energy to initiate a chemical reaction. Combustion reactions involve the rapid combination of a substance with oxygen, endothermic reactions absorb heat from the surroundings, and double displacement reactions involve the exchange of ions between two compounds. Therefore, the correct term for reactions requiring light energy is 'photochemical reactions,' making option C the correct answer.

5. 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.

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