Nursing Elites

1. Which type of bond is exemplified by KCl?

• A. Ionic bond
• B. Covalent bond
• C. Hydrogen bond
• D. Polar covalent bond

Correct answer: A

Rationale: KCl exemplifies an ionic bond. In an ionic bond, electrons are transferred between atoms, resulting in the formation of ions. In the case of KCl, potassium (K) donates an electron to chlorine (Cl), leading to the creation of K+ and Cl- ions, which are held together by electrostatic forces of attraction. Choice B, covalent bond, is incorrect because covalent bonds involve the sharing of electrons between atoms, not the transfer of electrons as seen in KCl. Choice C, hydrogen bond, is incorrect as hydrogen bonds are a type of intermolecular force, not a bond formed by the transfer or sharing of electrons between atoms. Choice D, polar covalent bond, is also incorrect because although it involves the sharing of electrons with an unequal distribution of charge, KCl is a clear example of ionic bonding where electrons are completely transferred.

2. Which of the following characteristics is part of a person's genotype?

• A. Brown eyes that appear hazel in the sunlight
• B. The CFTR gene, which causes cystic fibrosis
• C. Black hair that grows rapidly
• D. Being a fast runner

Correct answer: B

Rationale: The correct answer is B. A genotype refers to a person's genetic makeup, which includes specific genes like the CFTR gene responsible for cystic fibrosis. Genes are the units of heredity and are part of an individual's genotype, influencing various traits and characteristics. Choice A, brown eyes that appear hazel in the sunlight, refers to a phenotype, which is the observable characteristics resulting from the interaction of genes and the environment. Choice C, black hair that grows rapidly, also describes a phenotype rather than a genotype. Choice D, being a fast runner, is a trait influenced by a combination of genetic and environmental factors, but it does not directly relate to a specific gene in the genotype.

3. What is the term for the first exposure to a specific pathogen, leading to the development of an initial immune response?

• A. Primary immune response
• B. Secondary immune response
• C. Hypersensitivity reaction
• D. Immunological tolerance

Correct answer: A

Rationale: The correct answer is A: Primary immune response. The primary immune response refers to the initial encounter with a specific pathogen, which triggers the development of the first immune response by the immune system. This response involves activating immune cells like B cells and T cells to produce antibodies and memory cells specific to that pathogen. On the other hand, the secondary immune response occurs upon re-exposure to the same pathogen and is characterized by a faster, stronger, and more effective immune response due to the presence of memory cells from the primary response. Choices B, C, and D are incorrect. The secondary immune response is the response upon re-exposure, hypersensitivity reactions are exaggerated immune responses to antigens, and immunological tolerance is the immune system's ability to recognize and tolerate self-antigens without mounting an immune response.

4. What is the acceleration of an object moving at a constant speed of 20 m/s if it comes to a complete stop within 5 seconds?

• A. 0 m/s² (no acceleration)
• B. 4 m/s²
• C. -4 m/s²
• D. Insufficient information

Correct answer: C

Rationale: To find the acceleration, we use the formula: acceleration = (final velocity - initial velocity) / time. Given that the final velocity is 0 m/s (as the object stops), the initial velocity is 20 m/s, and the time taken is 5 seconds. Substituting these values into the formula, we get acceleration = (0 m/s - 20 m/s) / 5 s = -20 m/s / 5 s = -4 m/s². Therefore, the acceleration is -4 m/s², indicating that the object decelerated at a rate of 4 m/s² to come to a complete stop. Choice A is incorrect because the object does experience acceleration as it changes its speed from 20 m/s to 0 m/s. Choice B is incorrect as it represents acceleration in the wrong direction, considering the object is decelerating. Choice D is incorrect as there is sufficient information provided to calculate the acceleration based on the given data.

5. How do hydrogen bonds in water affect its characteristics?

• A. Hydrogen bonds are not polar enough to attract non-polar molecules.
• B. Hydrogen bonds cause water to be less dense when it is a solid than when it is a liquid.
• C. Hydrogen bonds cause water to have high surface tension, allowing some organisms to move across it.
• D. Hydrogen bonds cause water to be a good solvent.

Correct answer: C

Rationale: Hydrogen bonds in water contribute to its high surface tension, enabling some organisms to move across the water's surface. This property is essential for certain insects and small animals that rely on surface tension to move or stay afloat on water. Choice A is incorrect because hydrogen bonds are polar and can attract polar and other charged molecules. Choice B is incorrect as hydrogen bonds make ice less dense than liquid water, which is a unique property. Choice D is incorrect as the ability of water to act as a good solvent is primarily due to its polarity, not just hydrogen bonding.

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