Final answer:
Population size is the number of individuals in a population. Very small populations are at greater risk of extinction.
Step-by-step explanation:
Population size is the number of individuals in a population. For example, a population of insects might consist of 100 individual insects, or many more. Population size influences the chances of a species surviving or going extinct. Generally, very small populations are at greatest risk of extinction. However, the size of a population may be less important than its density.