Bacterial cell biology — The straightforward mechanism of binary fission explains how bacteria increase their numbers over time; what key cellular process does binary fission describe?

Introduction / Context:
Binary fission is the fundamental process by which most bacteria increase population size. Unlike mitosis in eukaryotes, binary fission is a streamlined, prokaryote-specific mechanism that duplicates the chromosome and segregates it into two daughter cells. This question tests whether you can link the term “binary fission” to the correct biological function in bacteria.

Given Data / Assumptions:

• Bacteria are prokaryotes lacking a membrane-bound nucleus.
• Binary fission involves DNA replication, segregation, and cytokinesis.
• The focus is on what the process accomplishes for the population as a whole.

Concept / Approach:
During binary fission, a single bacterium duplicates its circular chromosome at the origin of replication. The two DNA molecules are actively partitioned toward opposite ends of the cell as new membrane and peptidoglycan are inserted at the division septum. When constriction completes, two genetically identical (barring mutations) daughter cells are produced. Therefore, binary fission is directly synonymous with how bacteria reproduce to increase cell numbers. Growth on nutrient agar (colony expansion), evolution (genetic change over generations), and motility (movement) are related but distinct phenomena and not the definition of binary fission.

Step-by-Step Solution:

Verification / Alternative check:
Population growth curves in batch culture show exponential increases that reflect repeated cycles of binary fission; generation time (doubling time) measures the interval between reproduction events.

Why Other Options Are Wrong:

• Grow in nutrient agar: describes a culture condition, not the division mechanism.
• Evolve: long-term genetic change via mutation and selection, not a single-cell division event.
• Move: refers to motility (flagella, pili-based twitching), unrelated to division.

Common Pitfalls:
Confusing “growth” as biomass increase with “reproduction” as cell number increase; in microbiology, growth usually implies reproduction via binary fission.

Final Answer:
reproduce