Question

The semilog of per minute growing bacteria is ploted against time. What will the shape of graph : -

• A. Sigmoid
• B. Hyperbolic
• C. Ascending straight line
• D. Descending straight line

Answer 1

The Correct Option is C

To understand the shape of the graph when the semilog of per minute growing bacteria is plotted against time, let's delve into the concept of bacterial growth and how it is graphically represented.

Understanding Bacterial Growth:

Bacterial growth typically follows a pattern known as the bacterial growth curve, which progresses through several stages: lag phase, exponential (log) phase, stationary phase, and death phase. During the exponential phase, bacteria multiply at a constant rate, increasing rapidly.

Plotting Bacteria Growth on a Semilog Graph:

A semilog graph has one axis (usually the vertical axis) on a logarithmic scale. When plotting the number of bacteria (or the semilog of their number) against time during their exponential growth phase:

1. The semilog scale transforms the exponential growth into a linear relationship (straight line) because the logarithm of an exponential function is a linear function.
2. For the exponential growth, where the number of bacteria increases rapidly, the logarithmic transformation (semilog plot) results in an ascending straight line.

Conclusion:

The correct answer is Ascending straight line since plotting the semilog of exponentially growing bacterial populations against time results in an ascending straight line during the exponential phase.

Reason for Not Choosing Other Options:

• Sigmoid: This shape is more characteristic of the entire growth curve, but not for the semilog plot of the exponential phase.
• Hyperbolic: This represents a steady increase and plateau but does not apply to a semilog plot of exponential growth.
• Descending straight line: This would apply to a scenario where the population is decreasing, not growing.