Question

Which of the following statements is false about viruses?

• A. Viruses are obligate parasites.
• B. Viruses can multiply only when they are inside the living cells.
• C. Viruses cannot pass bacterial proof filters.
• D. Viruses are made up of protein and DNA or RNA.

Hint:

Remember the keyword “filterable agents”. Viruses are much smaller than bacteria and can pass through bacterial proof filters. This property played a crucial role in their discovery.

Answer 1

The Correct Option is C

Concept: Viruses are non-cellular obligate parasites that cannot metabolise independently and replicate only inside host cells. They consist of a nucleic acid core (DNA or RNA) and a protein capsid. A defining historical feature is their filterability—they pass through bacteria-retaining filters, which enabled their discovery.

Step 1: Evaluate obligate parasitism.
Lacking ribosomes, cytoplasm, and energy systems, viruses must hijack host machinery to reproduce. This statement is true.

Step 2: Evaluate multiplication requirement.
Outside a host, virions are inert; replication begins only after cellular entry. This statement is true.

Step 3: Evaluate filter passage.
Viruses are smaller than bacteria and readily cross bacterial-proof filters (e.g., Chamberland filters)—this is how they were first identified. Statement claiming they cannot pass is false.

Step 4: Evaluate composition.
Viruses contain protein and either DNA or RNA, never both as genetic material. This statement is true.

Final Answer: Option (C) is incorrect.