Understanding the Kingdom Fungi and Plant Kingdom
Kingdom Fungi (Fungi)
· Diverse organisms
· Fungi are a vast group of organisms; in some classifications, they are considered protists, while in others, they are grouped with plants, belonging to the Thallophytes.
· They can be unicellular or multicellular.
• In filamentous fungi, the strands are tangled together, forming a structure called mycelium. Each of the strands that make up the mycelium is called hypha and can consist of one or more nuclei, being coenocytic.
• The majority of fungi contain chitin and cellulose in their cell walls.
· Fungi are organisms without chlorophyll and thus cannot perform photosynthesis.
• The cytoplasm reserves starch, not glands, unless they contain oil drops or glycogen.
· Due to their inability to synthesize their own nutrients, they must obtain them from other living organisms (heterotrophic).
How do fungi live?
A large number of species are saprophytic, feeding on plant and animal residues and contributing to their breakdown. Many fungi, for example, decompose cellulose and are the main decomposers of wood. Many are parasitic fungi, typically guests of higher plants, but there are examples of parasitic fungi affecting various animals, including humans, causing diseases such as histoplasmosis. Some fungi have adapted a third way of life, living in symbiosis with another organism.
How do they reproduce?
By means of spores.
Phycomycetes
Rhizopus nigricans
– These are the easiest mushrooms to cultivate.
– They thrive on rotting fruit and when bread is moistened.
– They have structures called hyphae that form mycelium (a kind of mass).
– They have structures called runners that grow on the medium where they live (the medium is called the substrate).
– They have rhizoids that serve to adhere to the medium for absorption.
– They have sporangiophores that present terminal sporangia.
– Within the sporangia, spores are produced; once mature, the spores fall and can originate a new fungus.
– Reproduction may be
Asexual: through spores.
Ssexual: when two hyphae touch at their ends.
Ascomycetes
– These are the fungi that grow on organic matter such as cheese and fruit, forming a kind of mold.
– They are saprophytic fungi.
– Reproduction is usually asexual through spores.
– Sexual reproduction occurs very rarely.
Yeast: are a special group, mostly consisting of spherical cells.
– They have cell walls.
– They have cytoplasm that contains vacuoles and a nucleolus.
– Reproduction occurs by budding through structures called asci.
– Within the asci are called ascospores.
Basidiomycetes (Mushrooms)
– These fungi are more evolved.
– They consist of a structure called a pedicel, characterized by holding a cap-shaped structure called a stipe or pileus.
– The dorsal region is smooth.
– The ventral region is concave and presents dark radial plates called basidia.
– The basidia produce basidiospores, which are involved in reproduction.
– This group includes edible fungi, but also some that are toxic.
Plant Kingdom
Bryophytes (Liverworts and Moss)
– They are plants intermediate between algae and land plants.
– They were the first to adapt to terrestrial environments.
– They can live in damp, shady swamps.
– They have xylem and phloem (conducting vessels).
– They do not have tissues that can maintain an upright position.
– They are fixed to the ground by rhizoids.
– The basidia require the presence of water or moisture for sexual reproduction.
– Their sperm cells are characterized by being flagellated, requiring water for movement.
– They evolved from chlorophyte algae.
Liverworts
– They live in the Andean Cordillera and along the coast.
– They have a thallus that contains rhizoids.
– These allow them to anchor to the substrate.
– The thallus has pores involved in respiratory gas exchange.
– Reproduction
Asexual: occurs through organs called propagules or buds, which are located in specific structures.
Vascular Plants (Tracheophytes)
– They have xylem and phloem.
– The xylem vessels represent a set of conduits that carry water and minerals from the roots to the rest of the plant (this forms crude sap).
– The phloem vessels carry the end products of photosynthesis.
– These plants also have parenchyma, which provides structural support.
– They have true roots that anchor them to the substrate.
– The epidermis of these plants has structures that help minimize water loss.
– Stomata function to regulate gas exchange.
– Plants are important because they provide resources such as wood and food for human consumption.
Ferns
– They thrive in dark places.
– They have xylem and phloem.
– They have stomata.
– The stems of ferns are characterized by creeping and ascending structures called rhizomes.
– The rhizome has an epidermis that provides protection.
– The leaves are called fronds and are typically short.
– Ferns have large blades with small leaves called pinnae.
– The leaflets present structures called sori on their underside, which are involved in reproduction.
– The reproduction of ferns is alternated between
Asexual: the sori are inside sporangia that release mature spores, which fall and form the prothallus, which has rhizoids and young ferns.
Sexual: the antheridia produce sperm that swim with the help of water to fertilize the archegonia, forming the embryo sporophyte.
Mosses
– They are autotrophic and macroscopic plants.
– They are anchored to the ground by rhizoids.
– They do not produce flowers or fruits.
– They thrive in humid and tropical forests.
Polytrichum
– They have rhizoids.
– The life cycle is characterized by spores that fall into water, swell, and emit a filament that branches out, called young or moss protonema.
– The protonema develops buds that form gametangia (reproductive organs) called archegonia and antheridia.
– By joining the antheridium and archegonium, a zygote is formed.
– From the zygote, a sporophyte develops, comprising a pedicel and a capsule.
– Inside the capsule, spores are found, and the capsule is covered by a structure called calyptra.
– Eventually, the capsule opens, releasing the spores through a structure called operculum.