Nursing Elites

1. Which of the following describes a difference between cytosol and the mitochondrion?

• A. Cytosol is a membrane-bound organelle, but the mitochondrion is not
• B. Cytosol is part of the cytoplasm, but the mitochondrion is not
• C. The mitochondrion is a membrane-bound organelle, but cytosol is not
• D. The mitochondrion is part of the cytoplasm, but cytosol is not

Correct answer: C

Rationale: The mitochondrion is a membrane-bound organelle, while cytosol is the fluid part of the cytoplasm. This differentiation highlights that the mitochondrion has its own membrane structure separating it from the cytoplasm, whereas cytosol is not membrane-bound and represents the liquid portion of the cytoplasm. Choice A is incorrect because cytosol is not a membrane-bound organelle, and the mitochondrion is also not described accurately. Choice B is incorrect as cytosol is indeed part of the cytoplasm. Choice D is incorrect because both the mitochondrion and cytosol are part of the cytoplasm, but the mitochondrion is a membrane-bound organelle unlike cytosol.

2. Which enzyme plays a crucial role in DNA replication during the S phase of interphase?

• A. Helicase
• B. DNA polymerase
• C. Ligase
• D. Topoisomerase

Correct answer: B

Rationale: During the S phase of interphase, DNA replication takes place. DNA polymerase is the enzyme responsible for synthesizing new DNA strands by adding nucleotides in a complementary manner to the template strand. It plays a pivotal role in accurately replicating the entire genome. While helicase unwinds the double-stranded DNA for replication, topoisomerase relieves the tension in the DNA strands, and ligase joins the Okazaki fragments on the lagging strand. However, DNA polymerase directly participates in the synthesis of new DNA strands during replication, making it the correct answer.

3. Which of the following epithelial tissues lines the stratified squamous epithelium of the esophagus, providing a protective barrier against abrasion from food passage?

• A. Simple squamous epithelium
• B. Stratified squamous epithelium
• C. Simple cuboidal epithelium
• D. Stratified cuboidal epithelium

Correct answer: B

Rationale: The correct answer is stratified squamous epithelium. This type of epithelium is found in areas subjected to mechanical and chemical stresses, such as the lining of the esophagus. The multiple layers of cells provide protection against abrasion from the passage of food. Simple squamous epithelium (choice A) is a single layer of flat cells and is not well-suited for protection against abrasion as it lacks the multiple layers. Simple cuboidal epithelium (choice C) is found in areas where secretion and absorption occur, such as kidney tubules, and is not typically found in the esophagus where protection against abrasion is necessary. Stratified cuboidal epithelium (choice D) is rare in the body and is not a characteristic tissue type of the esophagus, which requires stratified squamous epithelium for its protective function.

4. The liver plays a vital role in digestion. What is one of the main functions of the liver in the digestive system?

• A. Physical breakdown of food
• B. Production of digestive enzymes
• C. Storage and processing of nutrients
• D. Elimination of waste products

Correct answer: C

Rationale: The correct answer is C: Storage and processing of nutrients. The liver plays a crucial role in processing nutrients absorbed from the small intestine, storing glycogen, vitamins, and minerals, and regulating blood sugar levels by releasing or storing glucose as needed. Choices A, B, and D are incorrect because the physical breakdown of food primarily occurs in the mouth and stomach, the production of digestive enzymes is mainly carried out by the pancreas and small intestine, and the elimination of waste products is primarily managed by the large intestine and kidneys, not the liver.

5. What is the primary purpose of control rods within a nuclear reactor?

• A. Reflecting neutrons back into the core
• B. Absorbing excess neutrons to control criticality
• C. Moderating the velocity of neutrons
• D. All of the above

Correct answer: B

Rationale: The primary purpose of control rods in a nuclear reactor is to absorb excess neutrons to control criticality. When inserted into the reactor core, control rods absorb neutrons, reducing the number available for sustaining the fission chain reaction. This action allows operators to manage the reactor power levels and prevent overheating or runaway reactions. Reflecting neutrons back into the core and moderating neutron velocity are not the primary functions of control rods in a nuclear reactor. Choice A is incorrect because control rods do not reflect neutrons back into the core but absorb them. Choice C is incorrect as the moderation of neutron velocity is typically achieved by other materials like a moderator (e.g., water, graphite) rather than control rods. Choice D is incorrect as control rods do not reflect neutrons or moderate neutron velocity, making it an incorrect option.

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