What happens when a population reaches its carrying capacity?

Resources will become scarce, and competition will rise. This can present in physical, political, or social ways. Once the population crosses the balancing point beyond carrying capacity, a number of things can happen that "correct" the problem, including out migration, starvation, disease, and conflict. Often more than one of things happens at the same time.

The ecosystem cannot support more growth

Explanation:

essentially, one bacterial cell splits into two daugurer cells. bacterial offspring don't need or get care from their parents because they are in a sense their own parents. that said, some bacteria can and do depend on other bacteria especially in harsh environments such as bacterial microfilms in hot water tanks.