Which statement about carrying capacity and logistic growth is correct?

• A. Carrying capacity is the maximum population size sustainable; logistic growth is S-shaped, leveling off as resources become limiting.
• B. Carrying capacity is the minimum population required for survival; logistic growth is exponential.
• C. Carrying capacity is the energy input to the ecosystem; logistic growth is constant.
• D. Carrying capacity is irrelevant to population dynamics; logistic growth continues indefinitely.

Answer: (A)

Carrying capacity is the maximum number of individuals an environment can sustain over the long term given the available resources and conditions. When a population is small and resources are plentiful, it grows quickly, but as numbers increase, competition for food, space, and other needs slows growth and eventually levels it off. The resulting pattern is S-shaped (logistic growth), approaching a stable level near carrying capacity. This is why the statement describing carrying capacity as the maximum sustainable size and logistic growth as leveling off as resources become limiting is correct. The other ideas misrepresent carrying capacity or the growth pattern: it’s not a minimum required for survival, nor is it simply the energy input to the ecosystem, and growth does not continue indefinitely but is regulated as resources become limiting.