What are general factors that affect population growth?

Resources relative to the population, e.g. food, clean water, air

Threats relative to the population, e.g. presence of predators, disease, or environmental dangers

Reproductive effectiveness: how many offspring does each couple have, and do the offspring correctly fabricated (not too many genetic mutations) so they are survivable.

Presence of another species that wants the population to survive. For example, ants sometimes keep aphids as a source of food. Perhaps more close to home, humans keep a population of cows as a food source.