Final answer:
A growth curve represents the changes in a microbial population over time and consists of four phases: lag, log, stationary, and death. Exponential growth denotes a consistent increase in growth rate and is typical in nature when conditions allow, but is often unsustainable. A positive growth rate indicates an increase, while a negative one signifies a population decrease.
Step-by-step explanation:
A growth curve is a graphical representation that shows the change in the number of cells of a microbial population over time. It typically has four distinct phases: lag, log (exponential), stationary, and death. During the lag phase, the cells acclimate to the environment, grow larger, and prepare for division without increasing in number. The log phase is characterized by rapid cell division and exponential increase in population. In the stationary phase, the growth rate slows down and stabilizes as resources become scarce. Finally, during the death phase, the number of dying cells surpasses the number of new cells, leading to a decline in the population.
Growth that is characterized by a consistent increase in growth rate is called exponential growth. This type of growth is often seen in nature when resources are abundant and population density is low. However, it is generally not sustainable over long periods since resources become limited, leading to logistic growth. Logistic growth initially follows an exponential pattern but slows as resource limitations become significant, resulting in a leveling off of the population.
It is important to note that a positive growth rate indicates an increasing quantity, whereas a negative growth rate means the quantity is decreasing. A larger growth rate indicates faster growth, while a smaller growth rate represents slower growth.