Population growth curvesसमष्टि वृद्धि वक्र

NCERT Fig 11.3 · Class 12 Biology · Chapter 11 · interactive diagram

Parts and their functions

• Exponential growth (J-shaped) (चरघातांकी वृद्धि (J आकार)) — When resources (food, space) are unlimited: dN/dt = rN. Integral form Nt = N0 e^rt. Numbers shoot up very fast.
• Logistic growth (S-shaped / sigmoid) (संभार तंत्र वृद्धि (S आकार)) — When resources are limited: dN/dt = rN (K − N)/K — Verhulst-Pearl logistic growth. Considered the more realistic model.
• Carrying capacity (K) (वहन क्षमता (K)) — The maximum number of a species a habitat can support; no further growth beyond it.
• Lag phase (पश्चता प्रावस्था) — Slow start of growth.
• Acceleration phase (त्वरण प्रावस्था) — Growth speeds up.
• Deceleration phase (मंदन प्रावस्था) — Growth slows as resources become limiting.
• Asymptote (अनंतस्पर्शी) — Population density reaches the carrying capacity K and levels off.
• Axes (अक्ष) — Population density (N) plotted against time (t).

Steps

1. (a) Unlimited resources → exponential growth, J-shaped: dN/dt = rN.
2. (b) Limited resources → logistic growth, S-shaped, levelling at carrying capacity K: dN/dt = rN (K − N)/K.
3. Phases of the S curve: lag → acceleration → deceleration → asymptote.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 11.3. Report a mistake