Nursing Elites

1. Which of the following is a common characteristic of alkynes?

• A. They have a triple bond between carbon atoms.
• B. They are saturated hydrocarbons.
• C. They contain only single bonds.
• D. They are aromatic compounds.

Correct answer: A

Rationale: Alkynes are hydrocarbons that contain at least one triple bond between carbon atoms. This triple bond is a distinctive feature of alkynes, distinguishing them from alkanes (which contain only single bonds) and alkenes (which contain at least one double bond). Alkynes are unsaturated hydrocarbons due to the presence of the triple bond. Aromatic compounds, on the other hand, have a specific cyclic structure with resonance stabilization, which is not a characteristic of alkynes.

2. The endocrine system communicates through chemical messengers called:

• A. Enzymes
• B. Hormones
• C. Antibodies
• D. Neurons

Correct answer: B

Rationale: The correct answer is B: Hormones. The endocrine system communicates through hormones, which are chemical messengers produced by various glands in the body. These hormones are released into the bloodstream and travel to target organs or tissues to regulate a wide range of bodily functions. Enzymes (A) are biological molecules that catalyze chemical reactions, not chemical messengers for communication within the body. Antibodies (C) are involved in the immune system's response to foreign substances. Neurons (D) are part of the nervous system and communicate through electrical impulses rather than chemical messengers like hormones.

3. The primary function of the atrioventricular (AV) node within the heart is to:

• A. Generate the electrical impulse for contraction (pacemaker function)
• B. Transmit the electrical impulse from atria to ventricles, regulating the timing of contraction.
• C. Increase blood pressure within the ventricles during systole.
• D. Separate oxygenated and deoxygenated blood flow in the heart.

Correct answer: B

Rationale: The correct answer is B: "Transmit the electrical impulse from atria to ventricles, regulating the timing of contraction." The AV node acts as a gateway between the atria and ventricles, ensuring a coordinated and sequential contraction of the heart chambers. It delays the conduction of electrical impulses to allow the atria to fully contract before the ventricles contract, facilitating efficient blood pumping. Options A, C, and D are incorrect because the primary role of the AV node is not to generate electrical impulses, increase blood pressure, or separate blood flow based on oxygenation status. Understanding the AV node's function is crucial in comprehending the heart's electrical conduction system.

4. Skeletal muscles are attached to bones by tough connective tissues called

• A. Ligaments
• B. Tendons
• C. Cartilage
• D. Fascia

Correct answer: B

Rationale: The correct answer is B: Tendons. Skeletal muscles are connected to bones by tendons, which are tough connective tissues that transmit the force generated by the muscle to the bone, allowing movement. Ligaments (A) connect bone to bone and provide stability to joints. Cartilage (C) is a smooth, firm tissue that covers the surface of bones at joints, reducing friction and absorbing shock. Fascia (D) is a connective tissue that surrounds muscles and other structures, providing support and protection.

5. In a covalent bond, the shared electrons:

• A. Are completely transferred to one atom.
• B. Spend more time closer to the more electronegative atom.
• C. Remain equidistant between the two atoms.
• D. Do not influence the bond strength.

Correct answer: B

Rationale: Spend more time closer to the more electronegative atom. Electronegativity determines the "pull" on shared electrons, with the more electronegative atom attracting them for a larger portion of the time, creating a partial negative charge near its nucleus.

6. What type of intermolecular force is responsible for the high surface tension of water?

• A. Hydrogen bonding
• B. London dispersion forces
• C. Ionic bonding
• D. Metallic bonding

Correct answer: A

Rationale: The high surface tension of water is due to the strong hydrogen bonding between water molecules. Hydrogen bonding is a type of intermolecular force that occurs when a hydrogen atom is covalently bonded to a highly electronegative atom (such as oxygen in water) and is attracted to another electronegative atom nearby. This results in a strong attraction between water molecules at the surface, leading to a high surface tension.

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