Question

In a typical bacterial growth curve, the first order kinetics for growth rate is observed in

• A. Lag phase
• B. Log phase
• C. Stationary phase
• D. Death phase

Hint:

In the log phase of bacterial growth, the population doubles at a constant rate, and the growth follows first-order kinetics.

Answer 1

The Correct Option is B

In a typical bacterial growth curve, the log phase (also called the exponential phase) is where the bacteria experience rapid growth and divide at a constant rate. During this phase, the population doubles at a fixed interval, and the growth rate follows first-order kinetics. In other words, the rate of increase in cell numbers is proportional to the number of cells present at that moment. Let's break down the options: - Lag phase (Option A): In the lag phase, bacteria are metabolically active but not dividing. They are preparing for cell division by synthesizing necessary enzymes, and no significant growth occurs during this phase, so first-order kinetics do not apply. - Log phase (Option B): This is the correct answer. During the log phase, bacterial cells are dividing at a constant rate, and the growth follows first-order kinetics, as the growth rate is proportional to the current population. - Stationary phase (Option C): In the stationary phase, the rate of bacterial growth slows down and eventually stops because nutrients become limited and waste products accumulate. The growth rate is not exponential here, so first-order kinetics do not apply. - Death phase (Option D): During the death phase, the number of dying cells exceeds the number of new cells being formed, so growth is no longer occurring. Therefore, first-order kinetics do not apply. Thus, the first-order kinetics for growth rate is observed during the log phase, which is the correct answer. Final Answer: \[ \boxed{\text{(B) Log phase}}. \]