Which of the following statements about viruses is true?

Step 1: Analyze the question We need to pick the one true statement about viruses.

Step 2: The concept Viruses are acellular, non-cellular particles made of genetic material (DNA or RNA) enclosed in a protein coat (capsid). They have no cytoplasm, no organelles and no metabolism of their own. They are only active when inside a living host cell, so they are called obligate intracellular parasites.

Step 3: Evaluate each option

• A. Viruses can reproduce outside of a host cell. False. Outside a host, a virus is inert. It has no ribosomes or enzymes to make copies of itself.
• B. Viruses require a host cell to replicate. True. A virus attaches to a host cell, injects or releases its genetic material, and hijacks the host's machinery (ribosomes, enzymes, energy) to make new viral particles.
• C. Viruses possess a cellular structure. False. Viruses are acellular. They have no cell membrane, cytoplasm or organelles.
• D. Viruses are living organisms. This is debatable and is not the best answer. Viruses show features of life only inside a host and are often described as being on the borderline between living and non-living. Most textbooks do not call them true living organisms because they cannot carry out metabolism or reproduction independently.

Step 4: Answer The correct option is B.

Step 5: Exam tip Remember the phrase "No host, no life." Whenever a JAMB question asks about viruses, think acellular, obligate parasite, needs a host to replicate. Be careful with options saying viruses are "living", because the examiners usually treat them as non-cellular and dependent on a host.