🧷 Authentic Classroom Explanation by IAS Monk

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📌 The Question:

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?

(a) Only one
(b) Only two
(c) All the three
(d) None

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✅ Answer:

(d) None

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🧑‍🏫 Authentic Classroom Explanation:

A virus is a submicroscopic infectious agent that replicates only inside living cells. Viruses infect all forms of life — animals, plants, fungi, bacteria, and even archaea. They are present in almost every ecosystem on Earth and are the most abundant biological entities known.

🔹 Statement I: No virus can survive in ocean waters — Incorrect

Viruses are extremely abundant in marine environments. Marine viruses, especially bacteriophages, are the most numerous biological entities in the oceans. They play a critical role in:

• regulating microbial populations
• nutrient recycling
• marine biogeochemical cycles

Viruses can survive in seawater for long periods depending on temperature, UV radiation, and salinity.

🔹 Statement II: No virus can infect bacteria — Incorrect

This statement is false because bacteriophages are viruses that specifically infect bacteria. They are ubiquitous in soil, freshwater, marine environments, and even the human gut. Phages are also being explored as alternatives to antibiotics in phage therapy.

🔹 Statement III: No virus can change cellular transcriptional activity in host cells — Incorrect

Viruses commonly manipulate host transcriptional machinery. After infection:

• Host gene expression is suppressed
• Viral genes are preferentially transcribed
• Host transcription factors are hijacked

This alteration is essential for viral replication and immune evasion.

📌 Therefore, none of the statements are correct.

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🔍 Curiosity Raiser:

Did you know? 🌊
👉 Oceans contain millions of virus particles per millilitre of seawater, and marine viruses destroy nearly one-third of oceanic bacteria every day, shaping Earth’s carbon cycle silently.

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🧠 Enrichment Notes (Prelims Edge):

• Bacteriophages are the most abundant biological entities on Earth
• Viruses exist in all ecosystems, including extreme environments
• Viral control of host transcription is key in:
  • oncogenic viruses
  • latent infections (e.g., herpesviruses)
• Marine viruses drive the viral shunt, recycling nutrients in oceans

📌 UPSC keywords: bacteriophage, viral shunt, host transcriptional hijacking

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🪔 IAS Monk Whisper:

“The smallest entities often govern the largest systems —
from cells, to oceans, to life itself.”