Food Manager Practice Exam

Which organism is 100 times smaller than bacteria and can only replicate within a host?

1. Parasites

2. Fungi

3. Viruses

4. Bacteria

The correct answer is: Viruses

The correct choice, viruses, is defined by their size and replication method. Viruses are notably smaller than bacteria, often measuring just 20 to 300 nanometers in diameter, making them approximately 100 times smaller than typical bacterial cells. Unlike bacteria, which can reproduce independently in diverse environments, viruses lack the cellular machinery necessary for replication. Instead, they must infect a host cell in order to reproduce, hijacking the host's cellular mechanisms to create more viral particles. This unique characteristic distinguishes viruses from other organisms like parasites and fungi, which have more complex structures and can often reproduce outside of a host. Therefore, the nature of viruses makes them the correct answer to this question.