The growth rate of a population during the exponential phase is and during the maximum stationary phase of growth are

Options

A. constant, zero
B. zero, constant
C. constant, constant
D. zero, constant

Answer

To answer the question regarding the growth rate of a population during different phases, we will analyze the phases of population growth and their characteristics.

### Step-by-Step Solution:

1. **Understanding Population Growth Phases**:
- Population growth can be divided into several phases: lag phase, exponential (log) phase, stationary phase, and death phase.
- The exponential phase is characterized by rapid growth, while the stationary phase indicates that the population has reached its carrying capacity.

2. **Exponential Phase Growth Rate**:
- During the exponential phase, the population grows at a constant rate. This means that the number of individuals added to the population per unit of time remains the same.
- Therefore, the growth rate during the exponential phase is **constant**.

3. **Maximum Stationary Phase Growth Rate**:
- In the maximum stationary phase, the population size stabilizes as it reaches the carrying capacity of the environment. At this point, the birth rate equals the death rate, leading to no net increase in population size.
- Hence, the growth rate during the maximum stationary phase is **0**.

4. **Conclusion**:
- Based on the analysis, we can conclude that the growth rate of a population during the exponential phase is **constant**, and during the maximum stationary phase, it is **0**.

### Final Answer:
The growth rate of a population during the exponential phase is **constant**, and during the maximum stationary phase, it is **0**.