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12 Biology Organisms and Populations - Set No : 4 Question No :2

Question No : 2
               Which type of age pyramid obtained when the population is growing?     

                a)          Bell-shaped age pyramid          b)          Urn-shaped age pyramid     

                c)          Triangular age pyramid          d)          Square-shaped pyramid     

Answer No : 2
     (c)Triangular age pyramid.Age pyramid Graphic representation of different age groups found in a population with pre-reproductive group at the base. Reproductive ones in the middle and post-reproductive group at the top is called age pyramid.Age pyramid have three kinds(i) Triangular Age Pyramid The number of pre-reproductive is very large. Number of reproductive individual is moderate and post-reproductive are fewer. Population size is growing(ii) Bell-shaped Age Pyramid The number of prereproductive and reproductive individuals is almost equal. Post-reproductive individuals are comparatively fewer. Population size is stable(iii) 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 sizable. It is declining population with negative growth     

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