Nursing Elites

1. When a muscle shortens and generates force, this is called a:

• A. Contraction
• B. Relaxation
• C. Extension
• D. Atrophy

Correct answer: A

Rationale: When a muscle shortens and generates force, it is contracting. Contraction is the process by which muscle fibers develop tension and exert a pulling force on the bones they are attached to, resulting in movement. Relaxation refers to the phase when a muscle returns to its original length, allowing for rest or preparation for the next contraction. Extension, on the other hand, is the movement that increases the angle between body parts, moving them further apart. Atrophy is unrelated to muscle contraction and refers to the wasting away or decrease in size of muscle tissue due to disuse or disease. Therefore, the correct answer is 'Contraction.'

2. How do vaccines stimulate the immune system to develop memory without causing full-blown illness? What type of molecule in a vaccine typically triggers the immune response?

• A. Toxins produced by the pathogen
• B. Live, attenuated (weakened) forms of the pathogen
• C. Inactivated (dead) forms of the pathogen
• D. Antigens (specific molecules) from the pathogen

Correct answer: D

Rationale: Vaccines work by triggering the immune system to develop memory without causing illness. They typically contain antigens, which are specific molecules from the pathogen. These antigens stimulate the immune system to produce a targeted immune response without causing full-blown sickness. By presenting these antigens, vaccines help the immune system create memory cells that remember the pathogen. This memory allows the immune system to respond more effectively if it encounters the pathogen in the future. Choices A, B, and C are incorrect because vaccines do not typically contain toxins, live pathogens, or inactivated forms of the pathogen. Instead, vaccines primarily rely on specific molecules (antigens) to induce an immune response.

3. Why are noble gas elements generally unreactive?

• A. They are too large and cannot form bonds easily.
• B. They lack valence electrons in their outermost shell.
• C. They have strong bonds within their own molecules.
• D. They have already achieved stable electron configurations.

Correct answer: D

Rationale: The correct answer is D. Noble gas elements are generally unreactive because they have already achieved stable electron configurations by having a full outer electron shell. This full shell makes them very stable and unlikely to gain, lose, or share electrons with other elements. Choices A, B, and C are incorrect because noble gases are not unreactive due to being too large to form bonds easily (A), lacking valence electrons in their outermost shell (B), or having strong bonds within their own molecules (C).

4. How many moles of water are produced when 0.5 moles of methane (CH4) react with excess oxygen?

• A. 0.5 moles
• B. 1 mole
• C. 2 moles
• D. 3 moles

Correct answer: B

Rationale: The balanced chemical equation for the combustion of methane is: CH4 + 2O2 -> CO2 + 2H2O. This equation shows that 1 mole of methane produces 2 moles of water. Therefore, when 0.5 moles of methane react, they will produce 1 mole of water. The ratio of water to methane is 2:1, meaning that for every mole of methane that reacts, it produces 2 moles of water. Since only 0.5 moles of methane are reacting, the amount of water produced will be half of what would be produced if 1 mole of methane reacted, resulting in 1 mole of water being produced. Choice A is incorrect because it does not consider the stoichiometry of the reaction. Choices C and D are incorrect as they do not align with the balanced chemical equation and the stoichiometric ratios involved in the reaction.

5. Melanin, the pigment responsible for skin color, is produced by

• A. Keratinocytes (These cells produce keratin)
• B. Melanocytes
• C. Sebocytes (These cells produce sebum)
• D. Langerhans cells (These cells are part of the immune system)

Correct answer: B

Rationale: Melanocytes are the cells responsible for producing melanin, the pigment that determines skin color. Melanin gives skin its color and protects it from the harmful effects of UV radiation. Keratinocytes produce keratin, a tough protein that forms the outer layer of the skin, hair, and nails. Sebocytes produce sebum, an oily substance that helps moisturize and protect the skin. Langerhans cells are a type of immune cell found in the skin that play a role in protecting against infections and foreign substances but do not produce melanin.

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