Nursing Elites

1. A light ray travels from air (refractive index 1.00) into water (refractive index 1.33). What happens to its speed and direction?

• A. Speed increases, direction bends towards the normal.
• B. Speed increases, direction bends away from the normal.
• C. Speed decreases, direction bends towards the normal.
• D. Speed and direction remain unchanged.

Correct answer: C

Rationale: When a light ray travels from air (lower refractive index) to water (higher refractive index), its speed decreases due to the change in the medium. This is because light travels slower in denser mediums. As the light ray enters the denser medium, water in this case, it bends towards the normal (the line perpendicular to the surface of the water). This phenomenon is known as refraction. Choice A is incorrect as the speed of light decreases when entering a denser medium. Choice B is incorrect as the direction bends towards the normal, not away from it. Choice D is incorrect as the speed and direction of the light ray do change when moving from air to water.

2. Melatonin is a hormone produced by the pineal gland. What is its primary function?

• A. Regulate blood pressure
• B. Stimulate the digestive system
• C. Control sleep-wake cycles
• D. Maintain bone density

Correct answer: C

Rationale: Melatonin is primarily known for its role in controlling sleep-wake cycles. It is produced by the pineal gland in response to darkness, helping signal the body that it is time to sleep. Melatonin levels typically rise in the evening and stay elevated throughout the night, promoting sleep. Choices A, B, and D are incorrect as melatonin's primary function is not to regulate blood pressure, stimulate the digestive system, or maintain bone density. While melatonin may have some indirect effects on these functions, its main role lies in regulating the circadian rhythm and promoting a restful sleep cycle.

3. How are the bones of the skull classified?

• A. Long bones
• B. Short bones
• C. Flat bones
• D. Irregular bones

Correct answer: C

Rationale: The bones of the skull are classified as flat bones. Flat bones are thin, flattened, and usually curved bones that provide protection to underlying organs and have a large surface area for muscle attachment. The skull bones fit this description as they protect the brain and have a broad surface for muscle attachment. Choice A (Long bones), B (Short bones), and D (Irregular bones) are incorrect classifications. Long bones are typically found in the extremities like the arms and legs, short bones are cube-shaped like the wrist and ankle bones, and irregular bones have complex shapes like the vertebrae. These classifications do not describe the bones of the skull, which are predominantly flat bones.

4. What is the difference between active and passive immunity?

• A. Active immunity is short-lived, while passive immunity is long-lasting.
• B. Active immunity involves the body's own immune response, while passive immunity provides immediate protection through antibodies from another source.
• C. Active immunity only protects against bacterial infections, while passive immunity works against both bacteria and viruses.
• D. Passive immunity requires repeated vaccinations, while active immunity is a one-time process.

Correct answer: B

Rationale: Active immunity involves the body's own immune response, where the individual's immune system produces antibodies in response to exposure to a pathogen or vaccine. This type of immunity is long-lasting because the immune system 'remembers' the pathogen and can mount a rapid response upon re-exposure. In contrast, passive immunity provides immediate protection through the transfer of pre-formed antibodies from another source, such as through maternal antibodies crossing the placenta or receiving antibodies through an injection. Passive immunity is short-lived because the transferred antibodies eventually degrade and are not produced by the recipient's immune system. Choice A is incorrect because active immunity is generally long-lasting, as it involves the production of antibodies by the individual's immune system. Choice C is incorrect as both active and passive immunity can work against various pathogens, not limited to bacteria or viruses. Choice D is incorrect as passive immunity does not require repeated vaccinations but provides temporary protection through the transfer of antibodies from an external source.

5. What causes lymphedema, a chronic condition, to occur?

• A. Inflammation of lymph nodes
• B. Blockage of lymph vessels
• C. Malfunction of the spleen
• D. Decrease in bone marrow production

Correct answer: B

Rationale: Lymphedema is a chronic condition that occurs when lymph vessels become blocked, leading to swelling and fluid retention in the affected area. Inflammation of lymph nodes, spleen malfunction, or decreased bone marrow production are not directly associated with the development of lymphedema. Lymph vessels play a crucial role in carrying lymphatic fluid, and when they are blocked, it disrupts the normal flow of fluid, resulting in lymphedema. Therefore, the correct answer is that lymphedema occurs when lymph vessels become blocked.

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