Together, the active stage and inactive, or spore-forming, stage of bacteria are referred to as the _____.

• A. Growth cycle
• B. Reproduction phase
• C. Binary fission process
• D. Life cycle of bacteria

Answer: (D)

Bacteria have a life cycle that includes both an active, growing stage and a dormant, spore-forming stage. These two phases together make up the life cycle of bacteria. In the active phase, cells are metabolically active and divide, often by binary fission. When conditions become unfavorable, some bacteria form endospores, which are highly resistant and can survive extreme environments until conditions improve. At that point, the spores germinate back into active cells and resume growth. So the term that covers both the active and spore-forming stages is the life cycle of bacteria. The other options describe only part of the process (growth or reproduction) or a specific mechanism (binary fission) rather than the entire sequence.