If $4$ individuals in a laboratory population of $40$ fruitflies died during a specified time interval (i.e.,a week),the death rate in the population during that period is

Which age group of organisms constitutes the pre-reproductive population?

Certain characteristic demographic features of developing countries are:

$A$ 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?

Under a particular set of selection pressure,organisms evolve towards the most $A$ reproductive strategy. Some organisms breed only $B$ in lifetime while others breed $C$ in lifetime. Choose the correct option for $A, B$ and $C$.

Population density of terrestrial organisms is measured in terms of individuals per