Nursing Elites

1. What is the primary function of the myelin sheath that surrounds some axons in the nervous system?

• A. To initiate nerve impulses
• B. To transmit sensory information
• C. To speed up the transmission of nerve impulses
• D. To connect neurons at synapses

Correct answer: C

Rationale: The primary function of the myelin sheath is to speed up the transmission of nerve impulses. The myelin sheath acts as an insulating layer around the axon, allowing for faster conduction of electrical impulses along the nerve fiber. This insulation prevents the electrical signal from dissipating or 'leaking' out, which helps in the rapid and efficient transmission of nerve impulses along the axon. Choice A is incorrect because the myelin sheath does not initiate nerve impulses; it helps in conducting them. Choice B is incorrect as the myelin sheath's main role is not in transmitting sensory information but rather in facilitating the transmission of nerve impulses. Choice D is incorrect because the myelin sheath's function is not to connect neurons at synapses; instead, it is primarily involved in enhancing the speed of nerve impulse transmission.

2. Which property of a substance resists a change in its shape?

• A. Density
• B. Mass
• C. Inertia
• D. Elasticity

Correct answer: D

Rationale: Elasticity refers to a material's ability to resist deformation and return to its original shape after stress is applied. It is the property that resists a change in shape. Density is the mass per unit volume of a substance. Mass is the amount of matter in an object, while inertia is the tendency of an object to resist changes in its state of motion. Viscosity, not mentioned in the question, is the resistance of a fluid to flow, not shape change.

3. Which of the following is an example of Mendelian inheritance?

• A. Incomplete Dominance
• B. Polygenic Alleles
• C. Combination Inheritance
• D. Recessive Inheritance

Correct answer: D

Rationale: The correct answer is D, 'Recessive Inheritance.' Mendelian inheritance involves traits controlled by single genes with dominant and recessive alleles. Incomplete dominance (choice A) is a non-Mendelian inheritance pattern where the heterozygous phenotype is a blend of the two homozygous phenotypes. Polygenic alleles (choice B) involve multiple genes contributing to a single trait, not following Mendelian principles. Combination inheritance (choice C) is not a recognized term in genetics and does not describe Mendelian inheritance patterns.

4. In the cardiovascular system, what does the term 'double circulation' refer to?

• A. The separation of oxygenated and deoxygenated blood flow within the heart.
• B. The regulation of blood pressure through vasoconstriction and vasodilation.
• C. The cyclic contraction and relaxation of the heart muscle.
• D. The existence of two separate circulatory pathways, one for the lungs and one for the body.

Correct answer: D

Rationale: The term 'double circulation' in the cardiovascular system refers to the existence of two separate circulatory pathways, one for the lungs (pulmonary circulation) and one for the body (systemic circulation). Oxygen-poor blood is pumped from the heart to the lungs for oxygenation, and then oxygen-rich blood is pumped from the lungs back to the heart to be circulated to the rest of the body. Choices A, B, and C are incorrect as they do not accurately describe the concept of 'double circulation.' Choice A refers to the separation of oxygenated and deoxygenated blood within the heart, choice B relates to blood pressure regulation mechanisms, and choice C describes the cardiac muscle's contraction and relaxation, none of which define 'double circulation' in the context of the cardiovascular system.

5. Which structure of the respiratory system bifurcates into the primary bronchi?

• A. Trachea
• B. Alveoli
• C. Bronchioles
• D. Larynx

Correct answer: A

Rationale: The trachea is the structure that bifurcates into the primary bronchi. The trachea is a tube that carries air to and from the lungs. It divides into the left and right primary bronchi at a specific point called the carina, which then further divide into secondary and tertiary bronchi, leading to the bronchioles. The alveoli are the tiny air sacs at the end of the bronchioles where gas exchange occurs, not the structure that bifurcates into the primary bronchi. Bronchioles are smaller airway branches that come after the bronchi but do not bifurcate into them. The larynx, also known as the voice box, is located above the trachea and is responsible for sound production, not the bifurcation into primary bronchi. Therefore, the correct answer is the trachea.

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