Question

The given graph represents the fastest multiplication rate of bacteria when they are added to rich broth.
The following graphs represent bacterial growth under different conditions, with increasing numbers of bacteria on the $y$-axis and increasing time on the $x$-axis.

Which graph describes the result of introduction of minimal nutrients for the first six hours and then addition of surplus nutrients?

• A. 1
• B. 2
• C. 3
• D. 4
• E. 5

Answer 1

The correct option is E 5

A bacterial cell undergoes several transitional changes when cultured on a nutrient media. These changes can be categorized as phases of growth. During initial stages when the bacteria adjust in the new environment, the nutrient uptake is slow due to low metabolic rate. This phase is known as lag phase. As the metabolic rate increases the nutrient uptake increases along with it and the phase is known as log phase. When all the nutrient in the solution depletes the bacteria enters the stationary phase.

Here, in the above-given graphs, Graph 5 shows slow growth rate in the initial stages. But the growth rate shoots up suddenly which clearly indicates the addition of surplus nutrient which is needed in log phase.

So, option E is the correct answer.