Question

Viruses are not classified as living because

• A. They lack the metabolic apparatus to reproduce outside their host cell
• B. They are simpler than prokaryotes
• C. They lack fimbriae
• D. They lack endoplasmic reticulum and nucleus

Hint:

Nature of Viruses: Acellular, obligate intracellular parasites lacking independent metabolic and protein-synthesizing machinery.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Viruses are acellular, obligate intracellular molecular genetic parasites lacking autonomous metabolic, ribosomal, and energy-generating machinery.

Step 2: Detailed Explanation:
In systematic virology and cell biology:
- Viruses exist as inert macromolecular assemblies (virions) outside the host.
- They completely lack ribosomes, protein synthesis machinery, ATP-generating metabolic cycles (glycolysis/respiration), and biosynthetic enzymes.
- Consequently, they possess no autonomous metabolic apparatus and cannot replicate or reproduce outside a living permissive host cell, placing them at the threshold between non-living chemistry and biological life.

Step 3: Final Answer:
Hence, viruses are not classified as living because They lack the metabolic apparatus to reproduce outside their host cell, corresponding to option (A).