Nursing Elites

1. Which property of a substance remains constant regardless of changes in its shape or size?

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

Correct answer: A

Rationale: The correct answer is 'Mass.' Mass is a measure of the amount of matter in an object and remains constant regardless of changes in its shape or size. Weight, volume, and density can all change depending on the conditions, but mass remains the same. Weight is the force exerted on an object due to gravity, which can change based on the gravitational pull. Volume is the amount of space an object occupies, which can change if the shape or size of the object changes. Density is the mass of a substance per unit volume, which can change if either the mass or volume changes. Therefore, in this scenario, mass is the property that remains constant regardless of changes in shape or size.

2. T cells in the immune system can be categorized into different types. What type of T cell directly kills infected body cells?

• A. Helper T cells
• B. Cytotoxic T cells
• C. Regulatory T cells
• D. Memory T cells

Correct answer: B

Rationale: Cytotoxic T cells directly kill infected body cells by recognizing specific antigens on the surface of infected cells and releasing cytotoxic substances to induce cell death, eliminating the infected cells. Helper T cells assist in coordinating the immune response, regulatory T cells help maintain immune tolerance, and memory T cells mount a faster and stronger response upon re-exposure to a previously encountered antigen. Therefore, the correct answer is cytotoxic T cells as they play a crucial role in directly targeting and destroying infected cells.

3. What is the primary purpose of control rods within a nuclear reactor?

• A. Reflecting neutrons back into the core
• B. Absorbing excess neutrons to control criticality
• C. Moderating the velocity of neutrons
• D. All of the above

Correct answer: B

Rationale: The primary purpose of control rods in a nuclear reactor is to absorb excess neutrons to control criticality. When inserted into the reactor core, control rods absorb neutrons, reducing the number available for sustaining the fission chain reaction. This action allows operators to manage the reactor power levels and prevent overheating or runaway reactions. Reflecting neutrons back into the core and moderating neutron velocity are not the primary functions of control rods in a nuclear reactor. Choice A is incorrect because control rods do not reflect neutrons back into the core but absorb them. Choice C is incorrect as the moderation of neutron velocity is typically achieved by other materials like a moderator (e.g., water, graphite) rather than control rods. Choice D is incorrect as control rods do not reflect neutrons or moderate neutron velocity, making it an incorrect option.

4. Which of the following antibodies can cross the placenta?

• A. IgA
• B. IgD
• C. IgG
• D. IgM

Correct answer: C

Rationale: The correct answer is IgG. IgG is the only antibody that can cross the placenta, providing passive immunity to the developing fetus. IgA, IgD, and IgM do not cross the placenta. IgA is mainly found in mucosal secretions, IgD is involved in the activation of B cells, and IgM is the first antibody produced in response to an infection, but it does not cross the placental barrier.

5. What is the difference between constructive and destructive interference of waves?

• A. They have different effects on wave amplitude.
• B. Constructive interference increases amplitude, while destructive interference decreases it.
• C. They affect wave amplitudes differently depending on the wave type.
• D. Their impact is determined by the relative phase of the waves, not wave speed or amplitude.

Correct answer: B

Rationale: Constructive interference and destructive interference are two phenomena that occur when waves interact. Constructive interference leads to an increase in wave amplitude when two waves meet in phase, resulting in the alignment of peaks and troughs. This alignment results in the combined wave having a higher amplitude. On the other hand, destructive interference causes a decrease in amplitude as two waves meet out of phase, leading to their cancellation. When peaks align with troughs, they cancel each other out, resulting in a lower overall amplitude. This difference in effect on wave amplitude distinguishes between constructive and destructive interference. Choice A is incorrect because it does not specify the direction of change in amplitude for each type of interference. Choice C is incorrect as both constructive and destructive interference can occur in various types of waves, not affecting them differently based on wave type. Choice D is incorrect because while the relative phase of waves does determine the interference type, it is the amplitude that is affected by constructive and destructive interference, not the wave speed.

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