At around 41°C, bacterial growth typically stops because:

• A. DNA replication accelerates uncontrollably.
• B. Bacteria enter a dormant spore state at this temperature.
• C. Enzymes begin to denature, inhibiting metabolic processes.
• D. Cell membranes become too rigid for transport.

Answer: (C)

Verified step by step guidance

1. Understand that bacterial growth depends on optimal conditions, including temperature, which affects cellular components and processes.
2. Recognize that at elevated temperatures, proteins such as enzymes can lose their functional shape, a process known as denaturation.
3. Recall that enzymes are crucial for metabolic reactions, including those involved in DNA replication, energy production, and cell wall synthesis.
4. Analyze why other options are less likely: DNA replication does not accelerate uncontrollably at high temperatures; spore formation is a specific response not triggered simply by 41°C; and membranes typically become more fluid, not rigid, at higher temperatures.
5. Conclude that the primary reason bacterial growth stops around 41°C is because enzymes begin to denature, which inhibits essential metabolic processes necessary for growth.