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Organisms and Populations — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYOrganisms and Populations3 Marks
Question
Describe the various types of age pyramids.
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Answer

Age pyramids are of three types:
  1. Triangular age pyramids: The number of pre-reproductive individuals is very large. Number of reproductive individuals is moderate while post-reproductive individuals are fewer. Population is growing.
  2. Bell shaped age pyramids: The number of pre-reproductive and reproductive individuals is almost equal. post-reproductive individuals are comparatively fewer. The population size remains stable.
  3. Urn shaped age pyramid: Proportion of reproductive age group is higher than the individuals in pre-reproductive age group. Number of post-reproductive individuals is also sizeable. It is declining population with negative growth.

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