Answer: The intrinsic rate of natural increase.
- A Total population size at the start of the observation period
- B Carrying capacity of the surrounding habitat
- C The intrinsic rate of natural increase
- D Time elapsed since the population began growing
Correct answer: C. The intrinsic rate of natural increase
Explanation: In the exponential growth model, r is the intrinsic rate of natural increase, reflecting the difference between birth and death rates under ideal conditions.
Exponential growth produces an ever-steepening J-curve with no limit, an unrealistic long-term model; logistic growth produces an S-curve that levels off at the carrying capacity K, as growth rate (K−N)/K shrinks to zero once resources are fully used.
Concept context
How organisms interact with abiotic factors and respond to stress, plus population attributes, growth models, and interspecific interactions such as predation, competition, and mutualism.