Nursing Elites

1. What property of a wave remains unchanged when it passes from one medium to another with the same speed?

• A. Frequency
• B. Wavelength
• C. Amplitude
• D. Speed

Correct answer: d

Rationale: The speed of a wave remains constant when passing from one medium to another with the same speed.

2. The adaptive immune system has two main branches: humoral and cell-mediated immunity. Which type of immune cell is primarily responsible for antibody production?

• A. Helper T cells
• B. Cytotoxic T cells
• C. B cells
• D. Natural killer cells

Correct answer: C

Rationale: The correct answer is C: B cells. B cells are a type of lymphocyte that plays a central role in humoral immunity by producing antibodies. When activated by antigens, B cells differentiate into plasma cells, which are responsible for producing and secreting antibodies. Helper T cells (option A) primarily assist in activating B cells and other immune cells. Cytotoxic T cells (option B) are involved in cell-mediated immunity, where they directly kill infected cells. Natural killer cells (option D) are part of the innate immune system and target virus-infected and cancerous cells. Therefore, B cells are the immune cells primarily responsible for antibody production in the adaptive immune system.

3. Repeating decimals can be expressed as fractions. Which of the following represents the decimal 0.7777... as a fraction?

• A. 77/1000
• B. 70/99
• C. 777/900
• D. 7/9

Correct answer: C

Rationale: Let x equal the decimal. Set up two equations such that the digits after the decimal point are identical. 1000x = 777.7777... 10x = 7.7777... Subtracting the two equations, we have 990x = 770. Dividing both sides by 990 gives us x = 770/990, which can be simplified to 77/90.

4. What is the waxy or oily substance produced by sebaceous glands that helps lubricate the skin and hair?

• A. Keratin
• B. Melanin
• C. Sebum
• D. Sweat

Correct answer: C

Rationale: The correct answer is C: Sebum. Sebum is a waxy or oily substance produced by the sebaceous glands in the skin. It helps lubricate and waterproof the skin and hair, preventing them from drying out. Keratin is a protein found in the skin, hair, and nails, providing structure and strength. Melanin is a pigment that gives color to the skin, hair, and eyes. Sweat is produced by sweat glands and helps regulate body temperature by cooling the skin through evaporation. In this question, sebum specifically refers to the substance produced by sebaceous glands, making it the correct answer.

5. Which of the following structures is responsible for preventing the backflow of blood from the left ventricle into the left atrium?

• A. Aortic valve
• B. Pulmonary valve
• C. Tricuspid valve
• D. Mitral valve

Correct answer: D

Rationale: The correct answer is D, the mitral valve. The mitral valve, also known as the bicuspid valve, is located between the left atrium and the left ventricle. Its main function is to prevent the backflow of blood from the left ventricle into the left atrium during ventricular contraction. The aortic valve (A) is responsible for preventing the backflow of blood from the aorta into the left ventricle, the pulmonary valve (B) prevents backflow from the pulmonary artery into the right ventricle, and the tricuspid valve (C) prevents backflow from the right ventricle into the right atrium. Therefore, the mitral valve is specifically responsible for preventing backflow in the left side of the heart, making it the correct answer in this case.

6. What is the SI unit of measurement for momentum?

• A. Newton (N)
• B. Kilogram-meter per second (kg·m/s)
• C. Joule (J)
• D. Newton-second (N·s)

Correct answer: b

Rationale: Momentum is measured in kilogram-meter per second (kg·m/s).

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