Nursing Elites

1. During which phase of the cell cycle does DNA replication occur?

• A. Interphase
• B. Mitosis
• C. Meiosis
• D. Cytokinesis

Correct answer: A

Rationale: Interphase is the phase of the cell cycle where the cell spends the majority of its time and is characterized by three subphases: G1 (Gap 1), S (Synthesis), and G2 (Gap 2). DNA replication specifically occurs during the S phase of interphase. This is a crucial step as it ensures that each daughter cell produced during cell division receives an exact copy of the genetic material. Mitosis is responsible for the equal distribution of the replicated DNA to the daughter cells during cell division. Meiosis is a specialized cell division process for gamete production in sexually reproducing organisms, involving two rounds of division to generate haploid cells. Cytokinesis is the final step of the cell cycle, where the cytoplasm divides to complete the formation of two separate daughter cells following nuclear division.

2. Two isotopes of the same element have different numbers of:

• A. Electrons
• B. Protons
• C. Neutrons
• D. Nuclei

Correct answer: C

Rationale: The correct answer is C: 'Neutrons.' Isotopes are variants of an element that have the same number of protons and electrons but differ in the number of neutrons they contain. This difference in neutron count is what distinguishes isotopes from each other while maintaining the same chemical properties. Choice A, 'Electrons,' is incorrect because isotopes of the same element have the same number of electrons. Choice B, 'Protons,' is incorrect because isotopes of the same element have the same number of protons. Choice D, 'Nuclei,' is incorrect as nuclei refer to the central part of an atom containing protons and neutrons, and the question specifically asks about differences between isotopes of the same element.

3. The dark, round structures observed within some bacterial cells are most likely:

• A. Ribosomes
• B. Flagella
• C. Endospores
• D. Capsules

Correct answer: C

Rationale: Endospores are the correct answer. Endospores are dark, round structures observed within some bacterial cells. They are highly resistant dormant structures formed by certain bacteria in response to harsh environmental conditions. Ribosomes are not dark, round structures within bacterial cells; they are responsible for protein synthesis. Flagella are long, whip-like appendages used for movement and are not dark, round structures within bacterial cells. Capsules are outer layers of polysaccharides that some bacteria produce for protection and adherence, not dark, round structures within bacterial cells.

4. Which of the following describes the difference between prokaryotic and eukaryotic cells?

• A. Prokaryotic cells have a nucleus, while eukaryotic cells don't.
• B. Eukaryotic cells are simpler in structure than prokaryotic cells.
• C. Prokaryotic cells have membrane-bound organelles, while eukaryotic cells don't.
• D. Eukaryotic cells have a true nucleus and membrane-bound organelles, while prokaryotic cells lack these.

Correct answer: D

Rationale: Eukaryotic cells have a true nucleus that contains the genetic material, while prokaryotic cells lack a true nucleus. Eukaryotic cells also have membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus, which are absent in prokaryotic cells.

5. Which part of the brain controls the pituitary gland and regulates hunger, thirst, and body temperature?

• A. Thalamus
• B. Hypothalamus
• C. Medulla oblongata
• D. Cerebellum

Correct answer: B

Rationale: The correct answer is B - Hypothalamus. The hypothalamus plays a crucial role in controlling the pituitary gland and regulating essential functions such as hunger, thirst, and body temperature. It acts as a vital link between the nervous system and the endocrine system, contributing to the maintenance of homeostasis in the body. Choice A, the Thalamus, is incorrect as it is primarily involved in relaying sensory information to the cerebral cortex. Choice C, the Medulla oblongata, is not responsible for regulating hunger, thirst, and body temperature; instead, it controls autonomic functions like breathing and heart rate. Choice D, the Cerebellum, is primarily associated with coordination and balance, not the regulation of endocrine functions or basic physiological needs.

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