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Q.
Total number of individuals of a species per unit area and per unit time is called
Organisms and Populations
Solution:
Population density is the number of individuals present per unit area or volume at a given time. If the total number of individuals is represented by letter $N$ and the number of units of space (area for land organisms and volume for water organisms) by letter $S$, then the population density $D$ can be represented as $D = N/S$. For instance, number of animals per square kilometre, number of trees per acre in a forest, etc.