Living Environment Regents Practice Test

What conclusion can be drawn from an experiment that shows fewer bacteria colonies with longer UV exposure?

1. The hypothesis is likely unsupported

2. Longer UV exposure limits bacterial growth

3. UV light has no effect on bacteria

4. Bacteria thrive under UV exposure

The correct answer is: Longer UV exposure limits bacterial growth

The conclusion that longer UV exposure limits bacterial growth is supported by the observation that fewer bacteria colonies were present with increased exposure time to UV light. This suggests that UV light, known for its germicidal properties, has a detrimental effect on bacteria. As the duration of exposure to UV light increases, the energy from the UV rays can cause damage to the DNA of the bacteria, leading to cell death or impaired reproduction. This aligns with established scientific understanding that UV light is effective in killing microbes and preventing their proliferation. Therefore, seeing fewer colonies indicates that longer exposure to UV is effective in minimizing bacterial growth, reinforcing the idea that UV light can be an effective method for disinfecting surfaces or environments where bacteria might thrive.