Nursing Elites

1. What does the T wave on an ECG correspond to?

• A. Atrial depolarization
• B. Ventricular depolarization
• C. Atrial repolarization
• D. Ventricular repolarization

Correct answer: D

Rationale: The T wave on an ECG corresponds to ventricular repolarization. Following ventricular depolarization, which is represented by the QRS complex, the ventricles undergo repolarization during the T wave. This phase signifies the recovery of ventricular muscle cells as they prepare for the subsequent depolarization cycle. Choices A, B, and C are incorrect because the T wave specifically reflects the repolarization of the ventricles, not the atria or their respective depolarization or repolarization phases.

2. Which of the following organelles is responsible for protein production in the cell?

• A. Ribosomes
• B. Golgi apparatus
• C. Mitochondria
• D. Lysosomes

Correct answer: A

Rationale: The correct answer is A: Ribosomes. Ribosomes are the organelles responsible for protein synthesis in the cell. They can be found either freely floating in the cytoplasm or attached to the endoplasmic reticulum. The Golgi apparatus (Choice B) is involved in processing and packaging proteins, not protein production. Mitochondria (Choice C) are responsible for energy production, not protein synthesis. Lysosomes (Choice D) are involved in digestion and waste removal, not protein production.

3. Which of the following produces the first heart sound ('lub')?

• A. The closing of the aortic and pulmonary valves
• B. The closing of the tricuspid and mitral valves
• C. The opening of the aortic and pulmonary valves
• D. The opening of the tricuspid and mitral valves

Correct answer: B

Rationale: The correct answer is B. The first heart sound, known as the 'lub' sound, is produced by the closure of the tricuspid and mitral valves, which are the atrioventricular valves. This sound marks the beginning of systole in the cardiac cycle. Choice A, the closing of the aortic and pulmonary valves, is incorrect as these valves produce the second heart sound ('dub'). Choice C, the opening of the aortic and pulmonary valves, is incorrect because the first heart sound occurs during ventricular contraction (systole). Choice D, the opening of the tricuspid and mitral valves, is incorrect as the 'lub' sound is associated with the closure, not the opening, of these valves.

4. During which developmental process does the first trimester of gestation roughly correspond?

• A. Embryogenesis
• B. Fertilization
• C. Meiosis
• D. Menstruation

Correct answer: A

Rationale: The correct answer is A: Embryogenesis. The first trimester of gestation involves the process of embryogenesis, where the basic structures of the embryo are formed. This period is critical for the development of major organ systems and the establishment of the embryo's overall body plan. Fertilization occurs at the beginning of pregnancy when the sperm fertilizes the egg, marking the start of embryonic development. Meiosis is a cell division process that produces gametes (sperm and egg cells) with half the number of chromosomes. Menstruation is the shedding of the uterine lining when pregnancy does not occur.

5. In an oxidation reaction,

• A. an oxidizing agent gains electrons.
• B. an oxidizing agent loses electrons.
• C. a reducing agent gains electrons.
• D. a reducing agent loses electrons.

Correct answer: B

Rationale: In an oxidation reaction, the substance being oxidized loses electrons, not gains them. An oxidizing agent is responsible for causing oxidation in another substance by accepting electrons, hence it undergoes reduction and loses electrons. Therefore, the correct statement is 'an oxidizing agent loses electrons,' making choice B the correct answer. Choices A, C, and D are incorrect because in an oxidation reaction, the oxidizing agent does not gain electrons, a reducing agent does not gain electrons, and a reducing agent does not lose electrons.

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