Which form of bacteria is resistant to heating and drying?

The correct answer is spore because spores are specialized dormant forms of bacteria that have developed resistance to extreme environmental conditions, including heat and dehydration. This resilience allows them to survive in harsh conditions that would typically kill other forms of bacteria.

When bacteria form spores, they undergo a significant transformation; they become encased in a protective coating that helps preserve their genetic material. This process, known as sporulation, enables them to remain viable for extended periods without access to moisture or nutrients.

In contrast, viruses do not possess the cellular structure characteristics of bacteria and cannot be classified in this context since they depend on host cells for replication and are generally more fragile than spores. Fungi, while capable of surviving in some adverse environments, do not have the same level of resistance as spores. Spirilla, a type of bacteria characterized by their spiral shape, do not exhibit the extra layer of protection that spores have, making them susceptible to heat and drying.