Question

A population is said to be mature or stable when

• A. It forms an age pyramid of urn shape
• B. It forms an age pyramid of bell shape
• C. It forms an age pyramid of triangle shape
• D. It forms an age pyramid of irregular shape

Answer 1

The correct option is B

It forms an age pyramid of bell shape

The correct option is B.

Explanation for correct option:

1. The number of pre-reproductive and reproductive individuals is usually equal in a bell-shaped age pyramid.
2. Post-reproductive individuals are comparatively fewer. It also represents a stable or stationary population, neither growing nor diminishing.

Explanation for incorrect options:

Option A:

1. In an urn-shaped age pyramid, the number of reproductive individuals is generally higher than the number of pre-reproductive individuals.
2. It also represents a declining or diminishing population with considerable negative growth.

Option C:

1. Triangular age pyramid has a high proportion of preoperative individuals, moderate no. of reproductive individuals & fewer post-reproductive individuals.
2. It represents a young or rapidly growing population.

Option D:

1. Irregular shape pyramid shows an unstable population.

Final answer: A population is said to be mature or stable when it forms an age pyramid of a bell shape.