If $8$ Drosophila in a laboratory population of $80$ died during a week, the death rate in the population is

What is formed by the aggregation of individual organisms of the same species?

$A$ population is correctly defined as having which of the following characteristics?
$(A)$ Inhabiting the same geographical area
$(B)$ Individuals belonging to the same species
$(C)$ Possessing a constant and uniform density and dispersion

$A$ biologist studied the population of rats in a barn. He found that the average natality was $250$, average mortality $240$, immigration $20$ and emigration $30$. The net increase in population is

$A$ population is a group of all . . . . . . in a given time.

"Population is an auto-regulated system" was said by