Consider the following statements: I. No virus can survive in ocean waters. II. No virus can infect bacteria. III. No virus can change the cellular transcriptional activity in host cells. How many of the statements given above are correct?

1. A. Only one
2. B. Only two
3. C. All the three
4. D. None

Answer: D

Explanation

All three statements are incorrect. Statement I is incorrect because viruses are abundant and active in ocean waters. Marine viruses, particularly bacteriophages, are the most numerous biological entities in the ocean and play crucial roles in regulating microbial populations and nutrient cycles. Statement II is incorrect. Bacteriophages are a specific type of virus that infects and replicates within bacterial cells. They are ubiquitous and play a significant role in controlling bacterial populations. Statement III is incorrect. Viruses frequently alter the transcriptional activity of their host cells upon infection. They manipulate the host’s gene expression machinery to facilitate viral replication and suppress host defenses, often by interacting with host transcription factors. Understanding the fundamental nature and impact of viruses is essential, especially given their role in diseases and ecosystems, making this a relevant topic for UPSC.