Nursing Elites

1. Antigenic variation, a common strategy used by some viruses, allows them to:

• A. Produce toxins
• B. Evade the immune system
• C. Survive outside a host
• D. Replicate rapidly

Correct answer: B

Rationale: Rationale: Antigenic variation is a strategy used by some viruses to evade the host's immune response. By constantly changing their surface antigens, viruses can avoid recognition and destruction by the immune system. This allows the virus to persist in the host and continue replicating, leading to prolonged infection and potential transmission to other hosts. Antigenic variation does not directly involve the production of toxins, survival outside a host, or rapid replication, making options A, C, and D incorrect in this context.

2. In the reaction 2Na + 2H2O → 2NaOH + H2, what is the limiting reactant when 3 moles of sodium react with 2 moles of water?

• A. Na
• B. H2O
• C. NaOH
• D. H2

Correct answer: a

Rationale: Sodium is the limiting reactant because it runs out first in a 1:1 ratio with water.

3. The largest level of ecological organization is a:

• A. Population
• B. Community
• C. Ecosystem
• D. Biome

Correct answer: D

Rationale: Rationale: A) Population: A population consists of individuals of the same species living in the same area. It is a smaller level of ecological organization compared to a biome. B) Community: A community consists of populations of different species living and interacting in the same area. It is a larger level of organization than a population but smaller than an ecosystem or biome. C) Ecosystem: An ecosystem includes all living organisms (biotic factors) and their physical environment (abiotic factors) interacting in a particular area. It is a larger level of organization than a community but smaller than a biome. D) Biome: A biome is the largest level of ecological organization and encompasses a large geographic area characterized by a specific climate, vegetation, and animal life. Biomes can be found on multiple continents and are defined by similar abiotic and biotic factors.

4. Which type of RNA carries the genetic code from DNA to ribosomes?

• A. Ribosomal RNA (rRNA)
• B. Transfer RNA (tRNA)
• C. Messenger RNA (mRNA)
• D. Deoxyribonucleic acid (DNA)

Correct answer: C

Rationale: Rationale: - Messenger RNA (mRNA) carries the genetic information from DNA in the cell's nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs. - Ribosomal RNA (rRNA) is a component of the ribosomes where protein synthesis takes place. - Transfer RNA (tRNA) is responsible for bringing amino acids to the ribosomes during protein synthesis. - Deoxyribonucleic acid (DNA) is the genetic material that contains the instructions for building and maintaining an organism. DNA is transcribed into mRNA before being translated into proteins.

5. What is the main verb tense in the following sentence? "She had already left before I arrived."

• A. Present tense
• B. Past tense
• C. Future tense
• D. t perfect tense

Correct answer: D

Rationale: The verb "had left" is in the past perfect tense, indicating an action completed before another past action ("arrived").

6. The feedback loop is a crucial concept in endocrine regulation. In a negative feedback loop, high levels of a hormone can:

• A. Further stimulate the release of the same hormone
• B. Inhibit the release of the hormone or its production
• C. Have no effect on the hormone's regulation
• D. Increase the need for another hormone entirely

Correct answer: B

Rationale: In a negative feedback loop, high levels of a hormone signal the body to stop producing more of that hormone in order to maintain homeostasis. This is a self-regulating mechanism to prevent excessive levels of the hormone. Option B is correct because in this scenario, the high levels of the hormone will inhibit its further release or production. This feedback loop helps ensure that hormone levels stay within a narrow range, preventing overstimulation or imbalance in the endocrine system. Options A, C, and D are incorrect as they do not align with the concept of negative feedback regulation in endocrine systems.

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