Nursing Elites

1. Which of the following structures is the natural pacemaker of the heart?

• A. Sinoatrial node
• B. Submental node
• C. Atrioventricular node
• D. Scalene node

Correct answer: A

Rationale: The sinoatrial (SA) node is often referred to as the natural pacemaker of the heart because it is a group of cells located in the right atrium responsible for initiating the electrical signals that coordinate the heart's contractions. The SA node sets the rate and rhythm of the heartbeats, making it a crucial component in the heart's function. The other options, Submental node, Atrioventricular node, and Scalene node, are not related to the regulation of the heart's electrical activity. The Submental node is a lymph node located under the chin, the Atrioventricular node is responsible for passing electrical signals from the atria to the ventricles, and the Scalene node does not exist in the context of the heart's electrical system.

2. How are sister chromatids distinguished from homologous chromosomes in meiosis I?

• A. Sister chromatids share the same centromere, while homologous chromosomes have different centromeres.
• B. Sister chromatids have identical DNA sequences, while homologous chromosomes have slightly different sequences due to crossing over.
• C. Sister chromatids repel each other, while homologous chromosomes attract each other during synapsis.
• D. Sister chromatids separate during anaphase I, while homologous chromosomes separate during anaphase II.

Correct answer: B

Rationale: In meiosis I, sister chromatids are exact copies of each other, containing identical DNA sequences. On the other hand, homologous chromosomes are pairs of chromosomes, with one inherited from each parent, and they can have different versions of genes due to genetic recombination during crossing over in prophase I. Choice A is incorrect because homologous chromosomes naturally have different centromeres. Choice C is incorrect as sister chromatids and homologous chromosomes do not exhibit repulsion or attraction during synapsis. Choice D is incorrect as sister chromatids separate during anaphase II, not anaphase I, while homologous chromosomes separate during anaphase I.

3. Which of the following is responsible for the body's fight-or-flight response?

• A. Pancreas
• B. Adrenal glands
• C. Thyroid gland
• D. Pituitary gland

Correct answer: B

Rationale: The correct answer is B: Adrenal glands. The adrenal glands are responsible for the body's fight-or-flight response. During stressful situations, the adrenal glands release hormones like adrenaline and noradrenaline, initiating the fight-or-flight response. These hormones prepare the body to either confront or flee from a perceived threat.\nChoice A - Pancreas: The pancreas is primarily responsible for producing insulin and regulating blood sugar levels, not the fight-or-flight response.\nChoice C - Thyroid gland: The thyroid gland is responsible for producing hormones that regulate metabolism, not directly involved in the fight-or-flight response.\nChoice D - Pituitary gland: The pituitary gland regulates various endocrine functions by releasing hormones, but it is not the primary gland responsible for the fight-or-flight response.

4. Which of the following phases of mitosis is characterized by the separation of sister chromatids and their movement to opposite poles?

• A. Metaphase
• B. Anaphase
• C. Telophase
• D. Cytokinesis

Correct answer: B

Rationale: During anaphase of mitosis, the sister chromatids, which are duplicated copies of a chromosome, separate and move towards opposite poles of the cell. This movement is facilitated by the shortening of microtubules attached to the chromatids. As a result, each pole of the cell receives a complete set of chromosomes, ensuring that the daughter cells produced after cell division will have the correct number of chromosomes. Metaphase is characterized by the alignment of chromosomes at the cell's equator, not their separation. Telophase is the phase following anaphase, where the separated chromatids reach the opposite poles and nuclear envelopes start to form around them. Cytokinesis is the final stage of cell division, where the cytoplasm is divided to form two separate daughter cells.

5. During swallowing, what is the role of the epiglottis, a small flap of cartilage located near the base of the tongue?

• A. Initiates the swallowing reflex
• B. Grinds food into smaller pieces
• C. Covers the trachea to prevent food aspiration
• D. Stores saliva for lubrication

Correct answer: C

Rationale: The epiglottis plays a crucial role during swallowing by covering the trachea to prevent food or liquid from entering the airway, which could lead to aspiration. By acting as a lid over the trachea, it ensures that food passes down the esophagus to the stomach, preventing it from entering the lungs. Choice A is incorrect as the swallowing reflex is a coordinated muscular action involving the tongue and throat muscles. Choice B is incorrect as grinding food into smaller pieces is primarily the function of the teeth and the initial stages of digestion. Choice D is incorrect as the storage of saliva for lubrication is not a function of the epiglottis, but rather involves salivary glands.

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