Q.32 Age pyramid having a bell-shaped polygon denotes:
1. Increasing population
2. Decreasing population
3. Stable population
4. Fluctuating population
A bell-shaped age pyramid shows a stable population due to nearly equal numbers across pre-reproductive and reproductive age groups, with fewer post-reproductive individuals. This shape indicates zero or slow growth.
Age Pyramid Basics
Age pyramids plot population by age and sex, revealing growth patterns. Shapes like triangle (broad base), bell, or urn (narrow base) reflect birth/death rates and life expectancy.
Bell shapes feature a wide middle, signaling demographic stability in developed regions.
Option Breakdown
Each choice links to pyramid traits:
-
Increasing population: Incorrect. This shows a triangular pyramid with a broad base (many young), indicating high birth rates.
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Decreasing population: Incorrect. Urn-shaped pyramids (narrow base, bulging top) denote this, with more elderly and low births.
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Stable population: Correct. Bell-shaped pyramids have similar pre- and reproductive group sizes, low post-reproductive, for constant size.
-
Fluctuating population: Incorrect. No standard pyramid shape matches irregular changes; these imply erratic growth.
Population Pyramid Types
| Shape | Denotes | Features |
|---|---|---|
| Triangular | Increasing | Broad base, narrow top |
| Bell-shaped | Stable | Wide middle, tapered ends |
| Urn-shaped | Decreasing | Narrow base, wide top |
