Microorganisms play a vital role in ecosystems and human life by performing essential functions such as nutrient cycling, decomposition, and supporting plant growth. In ecosystems, they break down organic matter, recycling nutrients like carbon, nitrogen, and phosphorus back into the environment, which supports plant and animal life. In human life, microorganisms are crucial for digestion, with bacteria aiding in food breakdown, and they contribute to the production of foods like yogurt, cheese, and antibiotics. Additionally, microorganisms help in bioremediation, breaking down pollutants, and in maintaining immune system health by balancing beneficial bacteria in the body.