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🔬 Biology  ·  Organisms and Populations  ·  NEET

If a population of size N is well below the carrying capacity K, the logistic growth equation dN/dt = rN(K-N)/K behaves most similarly to which model?

Answer: It behaves nearly like exponential growth, since (K-N)/K is close to 1.

  • A It approaches a growth rate of zero almost immediately under these conditions
  • B It behaves nearly like exponential growth, since (K-N)/K is close to 1
  • C It behaves like negative growth, with the population actively declining
  • D It is identical to the flattened logistic curve seen exactly at carrying capacity K

Correct answer: B. It behaves nearly like exponential growth, since (K-N)/K is close to 1

Explanation: When N is much smaller than K, the term (K-N)/K is close to 1, so dN/dt approximates rN, making early logistic growth resemble exponential growth before resource limitation slows it.

Exponential (J-curve) vs Logistic (S-curve) GrowthtimePopulation (N)Exponential (unlimited resources)K (carrying capacity)Logistic (limited resources)Logistic growth slows as N approaches K; exponential growth never slows down

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.

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