Nursing Elites

1. What is the principle behind optical fibers used in communication?

• A. Reflection of light within the fiber
• B. Refraction of light due to different densities within the fiber
• C. Total internal reflection guiding light through the fiber core
• D. Diffraction of light around bends in the fiber

Correct answer: C

Rationale: Optical fibers used in communication rely on the principle of total internal reflection guiding light through the fiber core. Total internal reflection occurs when light traveling through the core of the fiber is reflected back into the core due to the higher refractive index of the core compared to the cladding. This reflection ensures that the light remains confined within the core and propagates along the fiber without significant loss, allowing for efficient transmission of signals over long distances in optical communication systems. Choice A is incorrect because optical fibers do not primarily rely on simple reflection; instead, they utilize total internal reflection to guide light. Choice B is incorrect as the primary principle is not the refraction of light due to different densities within the fiber, but rather total internal reflection. Choice D is incorrect as diffraction is not the main principle behind optical fibers, which mainly rely on total internal reflection to guide light through the fiber core.

2. How does the Law of Conservation of Mass apply to this reaction: 2H₂ + O₂ → 2H₂O?

• A. Electrons are not lost.
• B. The hydrogen does not lose mass.
• C. New water molecules are formed.
• D. There is no decrease or increase in matter.

Correct answer: D

Rationale: The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction. In the given reaction, 2 moles of hydrogen combine with 1 mole of oxygen to form 2 moles of water. The total mass of the reactants (hydrogen and oxygen) is equal to the total mass of the products (water), meaning there is no decrease or increase in matter. The total mass of the system remains constant, demonstrating the conservation of mass. Choices A, B, and C are incorrect because the conservation of mass does not specifically relate to electrons, individual elements (like hydrogen), or the formation of new molecules; instead, it focuses on the overall mass of the system before and after the reaction.

3. Which part of the brain controls balance and coordination?

• A. Cerebrum
• B. Cerebellum
• C. Medulla
• D. Thalamus

Correct answer: B

Rationale: The cerebellum is the correct answer as it is the part of the brain responsible for controlling balance and coordination in the body. It receives input from various parts of the brain, spinal cord, and sensory systems to help coordinate voluntary movements. The cerebrum (choice A) is mainly involved in higher brain functions such as thinking, decision-making, and voluntary movements but not specifically balance and coordination. The medulla (choice C) is essential for functions like breathing, heart rate, and blood pressure regulation but not primarily for balance and coordination. The thalamus (choice D) acts as a relay station for sensory information but is not primarily responsible for balance and coordination.

4. What is the name of the cartilage flap that covers the trachea during swallowing, preventing food from entering the airway?

• A. Epiglottis
• B. Glottis
• C. Larynx
• D. Pharynx

Correct answer: A

Rationale: The correct answer is A: Epiglottis. The epiglottis is a cartilage flap located at the base of the tongue that covers the trachea during swallowing. Its primary function is to prevent food and liquids from entering the airway and instead directs them towards the esophagus. The glottis (choice B) refers to the space between the vocal cords in the larynx. The larynx (choice C) is the voice box containing the vocal cords responsible for phonation. The pharynx (choice D) is the throat region connecting the mouth and the esophagus, playing a role in both digestion and respiration.

5. Which blood vessels transport blood from the capillaries back to the heart?

• A. Arterioles
• B. Veins
• C. Venules
• D. Capillaries

Correct answer: B

Rationale: Veins are the correct answer as they are the blood vessels that carry blood from the capillaries back to the heart. Veins have thinner walls compared to arteries and contain valves to prevent blood from flowing backward. This transport of blood from the capillaries to the heart is essential for the circulatory system to maintain proper blood flow and oxygenation levels. Arterioles are small branches of arteries that lead to capillaries, not vessels that transport blood back to the heart. Venules are small vessels that collect blood from capillaries and lead to veins. Capillaries are the smallest blood vessels where the exchange of gases and nutrients occurs between blood and tissues, not vessels that transport blood back to the heart.

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