The physiological capacity to produce offspring is called

Define/Explain: Age composition.

$(a)$ Label the three tiers $1, 2, 3$ given in the above age pyramid.
$(b)$ What type of population growth is represented by the above age pyramid?

The tiger census in our national parks and tiger reserves is based on:

Density of population decreases when . . . . . . .

$A$ biologist studied a rat population at the time of birth. He observed that the estimated births were $250$, estimated deaths were $240$, $20$ rats immigrated into the population, and $30$ rats emigrated from the population. What was the net increase in the population?