Final answer:
Decomposers, such as fungi and bacteria, are important in food webs and ecosystems as they break down dead organisms and release nutrients back into the environment.
Step-by-step explanation:
Decomposers, such as fungi and bacteria, play a vital role in food webs and ecosystems. They break down dead organisms and release nutrients back into the environment, which is essential for cycling of nutrients like carbon, nitrogen, and phosphorus. Without decomposers, the nutrients would remain trapped in dead organisms and not be available to living things, causing many organisms to cease to exist.