During unfavorable conditions, some bacteria form what protective structure?

• A. Active stage
• B. Inactive or spore forming stage
• C. Pus
• D. Toxins

Answer: (B)

When conditions are unfriendly, some bacteria switch into a dormant, highly protective form called an endospore or spore. This inactive state encases the genetic material in a tough outer coat, keeps the core dehydrated, and includes protective chemicals, making it extremely resistant to heat, desiccation, chemicals, and radiation. The purpose is to survive until the environment becomes favorable again, at which point the spore can germinate back into a normal active cell. Because of this, the protective structure described is the inactive or spore forming stage. Pus and toxins aren’t protective structures the bacteria form in response to stress, and the active stage is the metabolically growing form, not a defense mechanism.