Fungi are a group of organisms that obtain nutrients by absorbing them from their environment. They are eukaryotic, heterotrophic and have cell walls made of chitin. Most fungi grow as thread-like filaments called hyphae and reproduce through spores.
Explanation
Fungi comprise a broad kingdom of organisms that includes molds, yeasts and mushrooms. They cannot make their own food through photosynthesis, so they digest organic material outside their bodies and absorb the resulting molecules. Their cell walls contain chitin, a tough polysaccharide also found in insect exoskeletons. Many fungi grow as a network of microscopic hyphae that collectively form a mycelium, which can extend through soil or other substrates. Yeasts are unicellular fungi that reproduce by budding. Filamentous molds form fuzzy growth on decaying food and produce conidia or sporangiospores. Dimorphic species can switch between yeast and filamentous forms depending on temperature or other conditions. Fungi reproduce both sexually and asexually, releasing spores that disperse in air or water and germinate under favourable conditions. Fungal metabolism plays a major role in decomposing dead plants and recycling nutrients in ecosystems. Humans exploit fungi for food fermentation (bread, beer, cheese), industrial enzymes and pharmaceuticals like antibiotics. Some fungi are pathogens that infect plants, animals or humans. Human diseases include athlete’s foot, ringworm, candidiasis and serious systemic infections in immunocompromised people. Plant pathogens such as rusts and smuts can devastate crops.
Examples and Importance
Yeasts such as Saccharomyces cerevisiae are used for baking and brewing. Molds like Penicillium produce penicillin and other antibiotics. Edible mushrooms include Agaricus bisporus, while poisonous species like Amanita phalloides contain potent toxins. Parasitic fungi, such as Candida albicans, can cause thrush and other infections in humans. Fungi also form mutualistic associations with plant roots (mycorrhizae) and lichens (a fungus and an alga or cyanobacterium) that contribute to soil fertility.
Fungi are diverse, adaptable organisms with ecological, industrial and medical importance. Their ability to decompose organic matter and form symbiotic relationships influences many natural processes. Understanding their biology is essential for controlling fungal diseases and harnessing beneficial species.