THE USEFUL AND HARMFUL EFFECTS OF FUNGI.
A fungus (plural: fungi[3] or funguses[4]) is any member of the group of eukaryote organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from the other eukaryotic life kingdoms of plants and animals.
Fungi do not have chlorophyll and are therefore incapable of carrying out photosynthesis. Many play an ecologically crucial role in decomposing dead organic matter, some are an important source of antibiotics or are used in fermentation, and others, cause disease. The familiar mushrooms and toadstools are merely the fruiting bodies of organisms that exist mainly as a thread-like mycelium
In addition, fungi are primarily responsible for keeping ecosystems piled up with the inorganic nutrients necessary for the growth of plants. without these decomposers, carbon, nitrogen, and other elements would remain tied up in organic matter. Plants and the animals that feed on them could not exist because elements taken from the soil would not be returned.
Fungi as Mutualists

Fungi may form mutualistic relationships with plants, algae, cyanobacteria, and animals. All these relationships have great ecological effects, which is very essential for balancing the ecosystem. Fungi as Medicines
Some fungi which have a parasitic relationship with insects such as caterpillars have also been typically used as medicines. Certain chemical compounds extracted from the fungus has been useful for treatments for cancer (certain types of cancer).
Penicillin, (a well-known antibiotic drug), is derived from a common fungus called Penicillium. A lot of fungi also make antibiotic substances, which are now vastly used to control diseases in human and animal