Question

1. the graph below represents the results of an investigation of the growth of three identical bacterial cultures incubated at different temperatures.

graph: y - axis: number of bacteria per ml of culture (ranging from 1,000 to 10,000), x - axis: time (hr) (0, 24, 48, 72, 96), three lines for 15°c, 10°c, 5°c starting from (0, ~3500)
which inference can be made from this graph?
a) temperature is unrelated to the reproductive rate of bacteria.
b) bacteria cannot grow at a temperature of 5°c.
c) life activities in bacteria slow down at high temperatures.
d) refrigeration will most likely slow the growth of these bacteria.

Explanation:

• Option A: The graph shows different growth rates at different temps, so temp is related to bacterial reproductive rate. Eliminate A.
• Option B: The \(5^\circ\text{C}\) curve shows growth (from 4000 to ~5000), so bacteria can grow at \(5^\circ\text{C}\). Eliminate B.
• Option C: Higher temps (15°C) have faster growth, so life activities speed up at higher temps. Eliminate C.
• Option D: Refrigeration is typically at low temps (like ~5°C). The graph shows slower growth at 5°C than 10°C/15°C, so refrigeration likely slows bacterial growth. This is correct.

Answer:

D) Refrigeration will most likely slow the growth of these bacteria.