The scientists incubated the bacteria at 37 °C. Students in school laboratories incubate bacteria at 25 °C. Explain why scientists use 37 °C but students must use 25 °C to incubate bacteria.

**Why scientists use 37 °C:** Scientists in professional laboratories use an incubation temperature of 37 °C because this is human body temperature. Pathogenic bacteria that infect humans, such as *Salmonella*, are adapted to thrive at this temperature. Using 37 °C ensures the bacteria grow at their optimal rate, leading to faster results for their investigation. **Why students use 25 °C:** In a school laboratory, safety is the primary concern. Incubating cultures at 37 °C would create the perfect conditions for the growth of potentially dangerous human pathogens. To minimise this risk, schools have a strict rule to incubate at a lower temperature, typically 25 °C. While bacteria will still grow, this temperature is significantly lower than the optimum for most human pathogens, greatly reducing the chance of culturing a harmful microbe to dangerous levels.