Final answer:
Population growth can be identified as either exponential (J-curve) or logistic (S-curve) based on how the population size changes over time. Exponential growth occurs with unlimited resources and shows a drastic increase, while logistic growth slows as resources become limited and stabilizes at the environment's carrying capacity.
Step-by-step explanation:
Understanding Population Growth Models
When analyzing population growth to determine the mode of population growth, one must differentiate between exponential growth (J-curve) and logistic growth (S-curve). Exponential growth is observed when a population has unlimited resources, leading to a rapid and continuously increasing growth rate. This is represented by a J-shaped curve because the population increases drastically over time. Conversely, logistic growth occurs when a population's growth rate increases rapidly but then slows down as resources become limited, eventually reaching a stable level known as the carrying capacity. The logistic growth model is illustrated with an S-shaped curve.
Through a careful examination of Figure 12.4.1, if a population size depicted on the y-axis continually rises without any sign of plateauing, it fits the exponential growth model described by curve A. However, if the population growth begins to level off at a certain point, this suggests logistic growth described by curve B. In natural populations, most species, including humans, initially have the potential for exponential growth, but it is usually limited by factors such as food, space, and other resources, leading to a logistic pattern.