Nursing Elites

1. What is the difference between a phylum and a class?

• A. Phylums are broader and more general
• B. Classes are broader and more general
• C. They are synonyms, used for the same groups
• D. Phylums are for plants, classes are for animals

Correct answer: A

Rationale: In biological classification, a phylum is a higher taxonomic rank than a class. A phylum is a broader category that encompasses multiple classes within it. It represents a group of organisms sharing a common body plan or evolutionary history. On the other hand, a class is a more specific category within a phylum that includes organisms with similar characteristics. Therefore, phyla are broader and more general compared to classes. Choice B is incorrect because classes are more specific categories within phyla. Choice C is incorrect as phyla and classes are distinct hierarchical levels in taxonomy. Choice D is incorrect because phyla and classes are not restricted to specific types of organisms; they can apply to various organisms across the biological kingdom.

2. Which of the following structures has the lowest blood pressure?

• A. Arteries
• B. Arterioles
• C. Venules
• D. Veins

Correct answer: D

Rationale: Veins have the lowest blood pressure among the listed structures. Blood pressure decreases as blood flows from arteries to arterioles, then to venules, and finally to veins. Veins return blood to the heart under low pressure because they have thinner walls and larger lumens compared to arteries and arterioles. This anatomical difference allows veins to accommodate a greater volume of blood without a significant rise in pressure. Arteries have the highest blood pressure to propel blood away from the heart, followed by arterioles which regulate blood flow to capillaries. Venules collect blood from capillaries and connect to veins, which then carry blood back to the heart at a lower pressure.

3. 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.

4. Myelin sheath is a fatty substance that insulates and protects the long extensions of some nerve cells. It is produced by:

• A. Schwann cells
• B. Astrocytes
• C. Neurons
• D. Oligodendrocytes

Correct answer: A

Rationale: Schwann cells are indeed responsible for producing the myelin sheath in the peripheral nervous system. These cells wrap around axons to form the myelin sheath, which enhances the speed of nerve impulse conduction. In the central nervous system, oligodendrocytes are responsible for producing the myelin sheath. Astrocytes provide support and maintenance functions for neurons, while neurons are the nerve cells themselves and do not produce myelin. Therefore, the correct answer is Schwann cells as they are specifically involved in myelin production in the peripheral nervous system.

5. What checkpoint mechanism ensures all chromosomes are attached to the spindle fibers before anaphase begins?

• A. Prometaphase
• B. Metaphase
• C. Cyclin degradation
• D. Sister chromatid cohesion

Correct answer: A

Rationale: A) Prometaphase is the correct answer because it is the stage of mitosis where all chromosomes are attached to the spindle fibers before anaphase begins. During prometaphase, the nuclear envelope breaks down, allowing the spindle fibers to attach to the kinetochores of the chromosomes. This attachment is necessary for proper chromosome alignment and segregation during anaphase. B) Metaphase is incorrect because it is the stage where chromosomes are aligned at the metaphase plate but do not necessarily have all spindle fibers attached. C) Cyclin degradation is incorrect because it is a regulatory mechanism that controls the progression of the cell cycle but is not specifically related to ensuring all chromosomes are attached to spindle fibers. D) Sister chromatid cohesion is incorrect because it refers to the physical connection between sister chromatids that is maintained until anaphase, but it does not ensure that all chromosomes are attached to spindle fibers.

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