ACT (Enhanced)ScienceMedium
A research assistant is analyzing data from an experiment on bacterial growth under varying pH levels. They have collected the following average colony counts after 24 hours: - pH 6.0: 120 colonies - pH 6.5: 180 colonies - pH 7.0: 250 colonies - pH 7.5: 230 colonies - pH 8.0: 160 colonies Based on these results, what is the most reasonable inference about the optimal pH for this bacterial strain's growth?
- AThe optimal pH is between 6.5 and 7.5.
- BThe optimal pH is exactly 7.0.
- CThe bacteria grow best in highly acidic conditions.
- DThe bacteria cannot grow at pH levels below 6.0.
Show answer & explanationAnswer & explanation
Correct answer: A. The optimal pH is between 6.5 and 7.5.
The highest colony count is at pH 7.0 (250 colonies), but the counts at pH 6.5 (180) and pH 7.5 (230) are also relatively high compared to the extremes. This suggests that the optimal pH range is centered around 7.0, specifically between 6.5 and 7.5, where growth is significantly elevated.
Why the other options are wrong
- B. While 7.0 shows the highest count, the data points are discrete. The optimal point could be slightly off 7.0 within the range.
- C. The highest growth is near neutral pH (7.0), not acidic (pH below 7.0). Growth at pH 6.0 is lower.
- D. There are 120 colonies at pH 6.0, indicating that the bacteria can indeed grow at this pH.
Inference from Data
Drawing logical conclusions or interpretations from observed data, often involving identifying trends, relationships, or optimal conditions.
- Goes beyond simply restating data points.
- Requires connecting observed patterns to broader scientific understanding.
- Must be supported by the presented evidence.
Memory trick: Optimal: Look for the 'peak' performance in the data.