Population growth: exponential and logistic

What you’ll practice

Build confidence with exponential and logistic population models, including interpreting curves, parameters, and ecological meaning.

You’ll also practice translating word problems into model choices (unlimited resources vs carrying capacity) and spotting when growth rate changes over time.

Quiz format and difficulty

Each question has 4 options and there’s no timer, so you can slow down and reason through graphs and equations.

Choose your preferred question count and difficulty before you start: shorter runs for quick review, or longer sessions to cover more edge cases; mixed difficulty blends fundamentals with tougher interpretation questions.

Common pitfalls to avoid

A lot of mistakes come from mixing up r (intrinsic growth rate) with population size (N), or assuming logistic growth is “linear” near carrying capacity.

Another frequent slip is misreading axes on growth graphs (N vs time versus dN/dt vs N) and confusing density-dependent with density-independent limiting factors.

Tips for better scores

• Check whether resources are assumed unlimited (exponential) or limited by K (logistic)
• Watch for which graph is shown: N vs t, dN/dt vs t, or dN/dt vs N
• Remember logistic growth has the fastest increase around N ≈ K/2
• Distinguish per-capita growth rate from total growth (r vs rN)
• Treat “carrying capacity” as an environmental limit that can change, not a fixed law
• Use units and context clues (birth/death rates, immigration/emigration) to choose the model