Fungi Honor

Nature Study

Requirements

Cite 3 characteristics of the Kingdom Fungi.
Answer: Three characteristics: (1) heterotrophic eukaryotes (they do not photosynthesize and absorb nutrients from the environment); (2) a cell wall composed of chitin (the same as arthropods, not cellulose like plants); (3) reproduction by spores, with a body formed by hyphae that together constitute the organism's vegetative fungal mycelium. — Fungi were separated from plants in 1969 by Whittaker in the five-kingdom system; chitin is the same polymer as the shells of insects and crustaceans — surprising evidence of evolutionary proximity; the largest organism on Earth is the fungus Armillaria ostoyae in Oregon, with 9.6 km² of connected underground mycelium.
Give the name of 3 classes of fungi and examples of each one.
Answer: Three classes: (1) Ascomycetes (Saccharomyces cerevisiae — baker's yeast, brewer's yeast); (2) Basidiomycetes (Agaricus bisporus — the common button mushroom; Amanita muscaria — poisonous); (3) Zygomycetes (Rhizopus stolonifer — black bread mold). Each class is distinguished by the reproductive spore structure formed. — Ascomycetes have an ascus (a sac with spores); basidiomycetes have a basidium (a club-shaped structure); zygomycetes form resistant zygospores. Saccharomyces was domesticated 9,000 years ago in Egypt for the fermentation of bread and beer; Amanita muscaria is the fairy-tale mushroom with a red cap and white dots.
Identify, in nature or through images, 15 fungi common in your country.
Answer: Fifteen common Brazilian fungi: button mushroom (Agaricus bisporus), shiitake, shimeji, bracket fungus (Pycnoporus), edible bolete (Boletus), Amanita muscaria, Aspergillus niger (black mold), Penicillium notatum, Saccharomyces cerevisiae (yeast), Candida albicans, Trichophyton (athlete's foot), Rhizopus (bread mold), Ganoderma lucidum (reishi), Pleurotus (king oyster mushroom), Lentinula edodes. — Brazil has high fungal diversity, with about 6,500 species cataloged by the List of the Flora of Brazil; Pleurotus ostreatus has been cultivated commercially in São Paulo since the 1960s; bracket fungi (Polyporales) are the most common in the Atlantic Forest and help in the decomposition of dead wood on the ground.
Give the name of 3 fungi that have economic value and state what the value of each one is.
Answer: Three economically important fungi: (1) Saccharomyces cerevisiae (yeast — used in bread, beer, and biofuel); (2) Penicillium chrysogenum (source of the antibiotic penicillin, discovered in 1928); (3) Agaricus bisporus (button mushroom — a food cultivated on a large scale). Each one moves billions of dollars in the current world market. — Saccharomyces sustains the beer industry (about 600 billion USD/year) and bioethanol (Brazil 30 billion USD); Penicillium revolutionized medicine, discovered by Alexander Fleming in 1928 and awarded the Nobel Prize in Medicine in 1945; cultivated button mushrooms move 16 billion USD/year according to the FAO's 2022 report on edible fungi.
Research and diagram the life cycle of 3 classes of fungi.
Answer: General cycle: spore germinates → forms a hypha → hyphae grow into mycelium → mycelium forms a fruiting body → the body releases new spores. In Ascomycetes, spores come from the ascus; in Basidiomycetes, from the basidium; in Zygomycetes, from the zygospore (resistant). There may be a cyclical sexual phase (with fusion of nuclei) and an asexual (mitotic) phase. — The fungal cycle alternates between haploid and dikaryotic phases (two nuclei per cell); sexual reproduction requires plasmogamy + karyogamy + meiosis; ascomycetes are a classic laboratory model (Saccharomyces cerevisiae, the first eukaryote to have its genome sequenced in 1996); basidiomycetes form visible mushrooms with a cap and stipe.
Name 5 diseases caused by fungi in humans, plants, or animals.
Answer: Five diseases: (1) candidiasis (Candida albicans, humans); (2) athlete's foot (Trichophyton, humans); (3) coffee leaf rust (Hemileia vastatrix, coffee); (4) bread mold (Rhizopus stolonifer, food); (5) onychomycosis (various fungi, nails). All caused by pathogenic fungi in humans, plants, or common foods. — Coffee leaf rust (Hemileia vastatrix) destroyed the plantations of Sri Lanka in 1869, shifting world consumption to tea; candidiasis affects about 75% of women at least once in their lives; the famous Irish Potato Blight of 1845 (Phytophthora infestans, a pseudo-fungus) killed a million people through famine.
What precautions should we take when observing and handling different types of fungi?
Answer: Use disposable gloves and never put your hands to your mouth, eyes, or nose; never eat a wild fungus without an expert's identification (some are deadly); wash your hands with soap after contact; avoid inhaling spores (some cause allergies or pneumonia); dispose of samples in a sealed plastic bag. — Amanita phalloides (the death cap) resembles edible mushrooms and kills 90% of those who ingest it through liver failure; Aspergillus spores can cause severe pulmonary aspergillosis in immunosuppressed people; mycology manuals from the SBM (Brazilian Society of Mycology) teach the use of basic PPE in practical classes with fungi.
Identify, in a practical class, the difference between a mold, a bracket fungus, and a mushroom.
Answer: Mold is a microscopic filamentous fungus that grows on foods as green, black, or white spots (e.g.: Penicillium on bread). A bracket fungus is a hard, fan-shaped basidiomycete that grows on living or dead trunks. A mushroom is a fleshy basidiomycete with a cap, gills, and a stipe (stalk) — like the button mushroom. — Molds (Zygomycota and Ascomycota) reproduce rapidly; bracket fungi (Polyporales) decompose dead wood, being essential to nutrient cycling; mushrooms (Agaricales) have the best-known fruiting body — all share hyphae and mycelium, but differ in the shape of the visible fruiting body.
Identify, in a practical class, the main parts of a basidiomycete.
Answer: Parts of the basidiomycete: the cap (pileus) covers the top; the gills or tubes under the cap produce spores on the basidium; the stipe (stalk) supports the cap above the ground; the volva is the enveloping base in some; the ring is the remnant of the protective membrane; and the mycelium is the underground network of hyphae that feeds the entire mushroom. — The pileus protects the gills where the basidia produce basidiospores; the volva and ring are important taxonomic markers — Amanita has both and that is why many species of the genus are toxic; the mycelium can extend over hectares — the largest known living being is the mycelium of Armillaria ostoyae in Oregon (USA) today.
What is the environmental importance of some fungi?
Answer: Decomposer fungi recycle organic matter (leaves, dead trunks, animals), releasing nutrients into the soil. Mycorrhizal fungi form a partnership with 90% of plants, helping with the absorption of water and phosphorus. Without them, ecosystems would collapse — forests depend on this invisible network for the transport of essential nutrients. — Mycorrhizae (Glomeromycota) have existed for about 460 million years and were essential for the colonization of land by plants; studies from the University of Reading (Suzanne Simard, 2018) show that trees exchange nutrients via the underground mycorrhizal network — the forests' "wood wide web" — a principle applied in modern forest management today.
Generally, what should the environmental conditions be for a fungus to live well?
Answer: Fungi prefer humid environments (60-90% humidity), with mild temperatures (15-30°C), little direct light (shade), a slightly acidic pH (4-7), and abundant organic matter for nourishment. That is why they appear in the bathroom, on forest floors, in forgotten foods, and on fallen trunks in the garden after rain. — These parameters are taught in the Manual of Medical Mycology (Lacaz, 2002); UV light inhibits many fungi — that is why clothes on the clothesline do not get as moldy; the optimal growth of Aspergillus occurs at 25°C with 80% humidity, conditions typical of the Brazilian tropical summer in the states of the Southeast and the North of Brazil.
How does a fungus feed itself?
Answer: A fungus feeds by heterotrophic absorption: the hyphae release digestive enzymes into the environment that break down organic matter into smaller molecules (sugars, amino acids), and then absorb these substances directly through the cell wall. It is external digestion — different from animals, which swallow and digest inside their bodies. — This process is called osmotrophy; enzymes such as cellulases and ligninases break down the cellulose and lignin of wood; white-rot basidiomycetes (Phanerochaete chrysosporium) are the only organisms capable of degrading lignin, being studied by bioengineering for the production of second-generation bioethanol in the laboratory currently.
Find at least one biblical reference to fungi.
Answer: The main biblical reference to fungi is in Leviticus 13:47-59 (a "plague of leprosy" in clothing of wool, linen, or leather) and Leviticus 14:33-57 (a greenish or reddish spot that spreads on the walls of houses). Although the text uses the word "leprosy," the description — green/reddish spots that spread on fabrics and damp walls — corresponds to what we identify today as mildew or mold (a fungus). The Law instructed washing, scraping the wall, removing the contaminated stones and, if the plague persisted, burning the item or demolishing the house, being one of the earliest records of sanitary management against fungal contamination. — The Hebrew word nega used in these texts means "plague" and covers both skin diseases and spots on surfaces; scholars such as Roland Kenneth Harrison in "Leviticus: An Introduction and Commentary" (1980) argue that the "leprosy" of houses was actually an infestation by fungi such as Stachybotrys, known today as dangerous black mold.