Identify the false statement about viruses (select the option that is NOT true).

Introduction:
A core property of viruses is their absolute dependence on living cells for replication. Distinguishing true foundational statements from false ones helps prevent conceptual errors in virology.

Given Data / Assumptions:

• We must choose the statement that is NOT true.
• Options include basic facts and one misleading claim.

Concept / Approach:
Viruses require host cell machinery to replicate; they cannot grow on inert media like bacteria or fungi can. Although we can culture viruses using cell lines, embryonated eggs, or live hosts, “pure culture in test tubes” without living cells is not possible.

Step-by-Step Solution:
Review each statement against virology fundamentals. Identify dependence on living cells as the key discriminant. Select the statement wrongly claiming growth in pure, cell-free media.

Verification / Alternative check:
Standard lab methods (cell culture, plaque assays) all rely on viable host cells; no routine cell-free “pure culture” growth exists for intact viruses.

Why Other Options Are Wrong (i.e., true statements):

• Obligate intracellular parasites: True for all viruses.
• DNA or RNA as genetic material: True; they never have both.
• Arising from fragments of cellular chromosomes: A plausible hypothesis; not proven but not a categorical falsehood.
• Integration into host genome: True for many, e.g., retroviruses and some DNA viruses.

Common Pitfalls:
Confusing “cell culture” (which uses living cells) with “pure culture” in nutrient broth; only the former supports viral replication.

Final Answer:
The false statement is “Viruses have been successfully grown in pure cultures in test tubes.”