Plant and Fungi Biology Vocabulary

Origin of Life Plants

Shared Derived Characters of Land Plants

• Apical meristems: localized regions of cell division in tips of roots and shoots, enabling directional growth.
• Alternation of Generations: Life cycle alternates between a multicellular haploid gametophyte and a multicellular diploid sporophyte.
  • Haploid gametophyte produces gametes via mitosis.
  • Gametes fuse to form a diploid zygote.
  • Zygote develops into a sporophyte, which produces haploid spores via meiosis.
• Multicellular, dependent embryos: embryo retained within tissues of female gametophyte and nourished by placental transfer cells.
• Multicellular gametangia: tissues in gametophyte which produce gametes; archegonium in females, antheridium in males (lost in seed plants).
• Walled spores produced in sporangia: tissues in sporophytes contain sporangia which protect spores, contain sporocytes: cells which produce haploid spores by meiosis.
  • Spores protected by sporopollenin.

Challenges Faced by First Land Plants

• Drying out: developed cuticle, a waxy coating that prevents water loss.
• Getting nutrients: relied on symbiotic relationships with mycorrhizae fungi to get water and organic nutrients, later through roots.
• Reproduction: sperm has to swim to egg, restricted to wet environments.
• Getting CO_2 for photosynthesis: early plants absorbed from air as in water; later plants have stomata to maximize gas exchange.

Kingdom Plantae

• Multicellular photosynthetic autotrophic eukaryotes.
• Cellulose in cell walls (like dinoflagellates, brown, and green algae due to convergent evolution).
• Nearly 300,000 known species.
• Important producers (50% global photosynthesis), supply oxygen.
• Mostly terrestrial environments, some returned to aquatic.

Moving to Land

• Ancestors of modern plants colonized land along with symbiotic mycorrhizae 475 mya.
• Photosynthetic prokaryotes (cyanobacteria) already there, confined to damp surfaces.
• First eukaryotes colonize land ~500 mya, first plants ~475 mya.

Key Adaptations for Land

• Cuticle: waxy coating that prevents water loss (missing in Bryophytes).
• Mycorrhizae: symbiotic fungi that help plants absorb more water and nutrients than they can alone.
• Stomata: microscopic pores in leaves to get CO_2 from the air; regulated to minimize water loss.

Bryophytes (Non-Vascular Plants)

• Lack vascular tissue, limits size.
• Some mosses have simple vascular tissue via convergent evolution, can get up to 2m.
• Liverworts don’t have stomata.
• Earliest plant lineages to diverge.
• Spores germinate → gametophyte (dominant stage).
• Sperm must swim to egg → bryophytes generally restricted to moist habitats.
• Sporophyte much smaller, dependent on gametophyte for nutrients.
• Gametophytes can reproduce asexually via brood bodies.
• Sporangium releases spores when conditions are favorable, single sporophyte can produce 50 million spores.
• Mosses form important symbiotic relationships with nitrogen-fixing cyanobacteria.
• Many can survive losing most of their water.
• Species living at high altitudes have compounds which absorb damaging UV radiation.

Ecological Roles of Bryophytes

• Sphagnum (peat moss) decays very slowly due to low temp, pH, O_2 level of peat bogs ⇒ decreased decomposition.
• Carbon sinks, storing ~30% global carbon.
• Peat can absorb 20X its weight in water ⇒ dead bodies become mummified.

Lycophytes, Monilophytes: Seedless Vascular Plants

• Vascular tissue: tube-shaped cells transport water (xylem), sugar (phloem) throughout plant, allowing plants to grow tall.

Vascular System

• Tracheids: tube-shaped cells that carry water and minerals up from roots (lost in aquatic species).
• One-way transport of water and minerals by xylem; cell walls reinforced with polymer lignin.
• Two-way transport of sugars and proteins by phloem.
• Allowed first plants to grow tall against gravity, increased light competition, first forests.
• Dominated 359-299 mya.
• Removed significant CO_2 during this period → cooling climate → glacial event; most plant species became extinct, climate too dry and cold.
• These forests eventually made themselves extinct when giant ferns cooled planet too much, then gymnosperms could grow tall and become more common through heat and pressure rich coal deposits.
• Earliest vascular plants ~425 mya; branched sporophytes allowed for increased complexity.
• Most have true root tissues (evolved independently in ancestors of lycophytes, rest of vascular plants).
• ferns need wet environment for sperm to swim to egg.
• First plants with true leaves.
• Sporophyte dominates life cycle, no longer dependent on gametophyte (much smaller).
• Still have flagellated sperm ⇒ consequently lycophytes, monilophytes mostly confined to damp environments.
• ~1,200 species of club mosses, spike mosses, quillworts (lycophytes) today.
• Ferns (monilophytes) diverse in tropics, thrive in temperate forests; ~12,000 species left.

Seedless Vascular Plants: Leaves

• Leaves increased surface area for photosynthesis.
• First microphylls ~410 mya (megaphylls 370 mya).
• Microphylls: spine-shaped leaves supported by single strand of vascular tissue; lycophytes only.
• Megaphylls: leaves with multiple branches of vascular tissue = veins nearly all vascular plants.
• Leaves evolved to carry reproductive structures; sporophylls: leaves that bear sporangia.
• Most lycophytes and monilophytes = homosporous: one type of sporangium, develops into bisexual gametophyte.
• Most seed plants = heterosporous: two types of sporangia produce two kinds of spores.
• Fern sporophylls produce clusters of sporangia (sori) on undersides of sporophylls.
• Most lycophytes, gymnosperms groups of sporohylls form cone like structures = Strobili.

Evolution of Seed Plants

• First seed plants (gymnosperm ancestors) evolved ~305 mya in giant lycophyte, monilophyte forests.
• Drier environment: thick cuticles, needle-shaped leaves, tender, moist gametophyte moved inside sporophylls.
• Gametophytes develop from spores retained in parental sporophyte, keeps them from drying out.
• Microsporangia produce pollen, male gametophyte inside.
• Integument: layers of sporophyte tissue (1 gymnosperm, 2 angiosperm) envelops megasporangium produces megaspore.
• Megaspore + megasporangium + integument = ovule; megaspore develops into female gametophyte.
• Seed: fertilized ovule → embryo + food + seed coat (formerly integument).

Angiosperms

• (fruit) (fruitjob is dispersal contain no nutrients for embryo).
• Fruit: mature ovary, can include other flower parts; seeds develop from ovules, ovary wall thickens.
• Can be fleshy (e.g. tomatoes, apples) or dry (e.g. walnuts, grains).
• Seeds pass unharmed through animal digestive tracts dispersed with fertilizer.

Importance of Seed Plants

• Domestication of seed plants transformed humans from hunter/gatherer to agricultural societies.
• Six crops yield 80% of our calories: corn, potatoes, wheat, rice, cassava, sweet potatoes.
• Provide: tea, coffee, spices, paper, medicines like digitalin, pain relievers like morphine.
• Growth of body vs. reproductive effort:
  • r selected: short time for growth then moves on to reproductive efforts.
  • k selected: longer time for growth before reproductive efforts.

Structure of Plants: Leaves

• Leaves also evolved for specialized functions:
  • Plantlets by asexual reproduction.
  • Water storage (e.g. aloe).
  • Defense (e.g. cactus spines) thorns modified leaves.
  • Clinging or climbing like vines.

Structure of Plants: Tissues

• Plants have a 3 tissue system:
  • Vascular: xylem and phloem, transport water, nutrients between roots and shoots.
  • Dermal: epidermis, protection.
  • Ground: storage, photosynthesis.
• Trichomes on epidermis used to defend from insects, reflect UV.
• Stomata high surface area to volume ratio.
• Cellulose is hydrophilic allows water to crawl up the sides, how water from roots gets to 199 Synthesis.
• More sugar in leaves than needed so extra gets pulled down to stem and roots.
• Plants can reproduce asexually through nodes on stems. Estem tissue.

Structure of Plants: Roots

• Root: organ that anchors plant, absorbs water, minerals, can store excess sugars.
• Taproot: long, main vertical root; best for soils with deep groundwater, tall plants.
• Root hairs: thin tubes extending from root epidermis; main site of water, nutrient absorption.
• Adventitious roots: roots that arise in unusual place form fibrous networks near soil surface.
• Help grasses hold topsoil, prevent erosion.
• Roots can be adapted for different functions: storage of carbohydrates (e.g. carrots).
• Roots can be adapted for different functions:
  • Extra support (buttress, prop roots).
  • Acquiring oxygen in waterlogged environments 2 pneumatophores project above water surface.

Fungi Evolution

• Multicellularity likely evolved independently in fungi, animals, others.
• Oldest accepted fossils are 460 mya (terrestrial) likely evolved from aquatic protist.
• Chytrid fungi are basal taxon: flagellated spores, some without chitin in cell walls (key adaptation for life on land).

Taxonomy: Kingdom Fungi

• Chytrids (1,000 species) may be paraphyletic.
• Zygomycetes (1,000 species).
• Glomeromycetes (160 species).
• Ascomycetes (65,000 species).
• Basidiomycetes (30,000 species).

Chytrids

• Common in lakes, soil; species are parasites, decomposers.
• Flagellated spores = zoospores (shared derived character) likely inherited from protist ancestor.
• Infection by Batrachochytrium dendrobatidis at least partially responsible for global amphibian decline.

Zygomycetes

• Haploid fungi produce spores by Mitosis.
• Diploid fungi produce Spores by Meiosis.
• Includes most molds that form on food fungal fruiting, aka sporangia.

Glomeromycetes

• Important symbiotic relationship.
• Includes most mycorrhizae.

Ascomycetes

• Species are decomposers, pathogens, lichens.
• Fruiting bodies in sexual stage = ascocarps contain saclike spore-producing structures (asci).
• • Symbiotic relationship between 2 organisms.

Basidiomycetes

• Includes mushrooms, shelf fungus, puffballs; species are parasites, decomposers (best at breaking down cellulose, lignin).
• Form fruiting bodies in sexual stage = basidiocarps.
• Spore-producing cells called basidia produce spores by meiosis (like asci, fruiting bodies of zygomycetes).
  release billions of haploid spores through “gills”.
• Basidium
  • -2 rounds cell division
  • -4 genetically distinct spores. G genetic recombination.

Fungi As Pathogens

• Mycosis: fungal infection
  • Athlete's foot.
  • Yeast infections.
  • Fungal pneumonia.
  • Rusts, smuts on crops.

Fungus Among Us

• Truffles, morels, make cheese.
• Yeast brewing, baking; converts sugar alcohol and CO_2.
• Antibiotics (penicillin!), immune suppressants for organ transplants.
• Raw component of LSD (lysergic acid) comes from parasitic ascomycete which grows on rye.

Taxonomy: Kingdom Animalia

• Most protists that share close common ancestor with animals, fungi also have flagella.
• DNA evidence indicates these four taxa form monophyletic group.
• Unicellular flagellate protist ancestor Nucleariids Fungi Choanoflagellates Animals.
• What is on the main way that you go from spores

Gymnosperm Life Cycle

• Megasporangia spore bearing tissue sitting on spore bearing leaf ovulate cones gymnosperms carpals in angiosperms sporophylls conflicts megasporocytes go through meiosis to make megaspores one develops into female gametophyte inside ovule goes through mitosis to make eggs mm.
• Microsporangia spore bearing tissue sits on Sporophyll spore bearing leaf pollen ones in gymnosperms anthers in angiosperms microsporphytes gothrough meiosis to make microspores pollen grain inside this male gametophyte will go.
• Through mitosis to make sperm cells 2 sperm cells in gymnosperms one is pollen tube cell which digests the megasporangiu issue to allow the other sperm cell to get to egg for FERTILIZATION seed is fertilized ovule becomes food in gymnosperms
  Ovule megasporangium megaspore integument outer layer of sporophyte tissue becomes seed coat.

What’s So Great About Seeds?

• Ovules, pollen, no longer tied to moist habitats.
• Seeds can disperse over large distances, remain dormant over long periods.
• Can colonize wide variety of habitats, wait out unsuitable conditions.
• Seeds provide food, protect embryo from dessication, predators, UV light.

Gymnosperms

• Naked seeds exposed on clusters of sporophylls (cones).
• First evolved ~305 mya; dominated until ~65 mya (dinosaur food).
• Some retain flagellated sperm (ginkgos, cycads).
• Pollen spread by wind; pollination occurs when pollen lands at sticky base of sporophyll.
• Phylum Cycadophyta: palm-like leaves, large cones; most endangered.
• Phylum Ginkgophyta: one surviving member, G. biloba; deciduous, fleshy seeds smell like rotting cheese turns gold in fall.
• Phylum Coniferophyta: pines, firs; ancient bristlecone pines (among oldest living things); giant sequoias (among tallest, oldest).
• Includes junipers, berries actually fleshy sporophylls.

Angiosperms (Flowering Plants)

• First appear ~140 mya, rapid adaptive radiation.
• Flowers: specialized structure for sexual reproduction; pollinated by wind or animals (e.g. bees, bats); contain up to 4 rings of modified leaves:
  • Sepals: enclose flower before it opens.
  • Stamens: produce microspores pollen, contain male gametophytes; filament with terminal anther.
  • Carpels: produce megaspores female gametophytes (may be one or several fused together); stigma receives pollen, style leads to ovary at base; each ovary may contain multiple ovules.
• Some self-pollinate; most have mechanisms to prevent (avoid inbreeding).
• Pollen contains two cells: one develops into pollen tube; other divides into two haploid sperm cells – one sperm fertilizes egg, other fuses with gametophyte triploid cell = double fertilization (unique to angiosperms) endosperm, tissue that nourishes developing embryo.
• Ovule matures into seed; zygote embryo with rudimentary root one or two seed leaves cotyledons.

Shared Derived Characteristics for Angiosperms:

• Flowers
• Fruit
• Double fertilization to form endosperm
• 2 layers of integument on ovule

Characteristics of Fungi

• ~ 1.5 million species, found in every habitat; unicellular forms = yeasts, found in moist environments.
• Heterotrophs secrete powerful hydrolytic digesting enzymes into environment, absorb nutrients (organic matter) can break down lignin, cellulose Primarily responsible for inorganic nutrient recycling Can digest mitosis makes pores by mitosis weird variety of organic waste including animal corpses.
• Most multicellular, composed of thin filaments = hyphae, septa between cells have pores.
• Cell walls strengthened by chitin (flexible polysaccharide).
• Hyphae high surface area to volume ratio.
• Some exist in both filamentous, unicellular forms fungi like to be haploid relies on mutation for genetic diversity germinate where they land if food available.

Fungal Life Cycle

• Haploid fungi produce spores by mitosis sometimes produced by fruiting bodies what we see above ground.
• Most haploid fungi form temporary diploid stages when hyphae from each partner fuse.
• Mycelium can recognize its own, and similar, hyphae. Fusion of cytoplasm of parent mycelia plasmogamy.
• Nuclei don’t fuse right away fused mycelium with nuclei from two different individuals = heterokaryo can last days years sometimes two exchange genes.
• Followed by karyogamy haploid nuclei fuse > diploid zygote.
• Zygote almost immediately develops into sporangium (fruiting body) haploid spores by meiosis.

Taxonomy: Kingdom Fungi

• Unicellular flagellate protist ancestor Unicellular protists such as amoebas.
• Most protists that share close common ancestor with animals, fungi have flagella DNA evidence indicates these four taxa form monophyletic group More on these in EdPuzzle.
• ~ 1.3 million extant species; common ancestor ~ 770 mya likely suspension feeders like choanoflagellates.
• 3.8 bya first prokaryotes oxygen revolution 2.7 bya 1.8 bya first eukaryotes first animal fossils 560 mya (aquatic).
• Cambrian explosion = adaptive radiation of protists (especially algae), animals Animal know order things happen not s 535 mya oldest fossils of extant phyla led to first large animals with mineralized skeletons large increase in predators.

Kingdom Animalia

• Very few definitive shared derived characters; multicellular eukaryotes with no cell wall external cell membrane proteins provide support.
• Collagen: unique protein mainly used to connect cells.
• Heterotrophs which use enzymes like fungi, but must ingest, cannot absorb directly.
• Many have specialized cells not found in other taxa (e.g. muscles and nerves) organized into tissues.
• Two key dermal layers formed tissues in embryo:
  • ectoderm: layer covering embryo’s surface nervous system.
  • endoderm: innermost layer,
• Sponges lack true tissues; some animals diploblastic: ectoderm, endoderm only; all others have third layer between = mesoderm: forms when ectoderm cells migrate inward, lining these animals are triploblastic.
• Most triploblastic animals have coelom: body cavity formed from mesoderm between digestive tract, body wall; coelom cushions organs, site of muscle attachment like internal skeleton.

Features of Animals

• Radial symmetry: no front or back, left or right (e.g. anemone).
• Often sessile or planktonic.
• Most have bilateral symmetry: top (dorsal), bottom (ventral), left and right side (lateral), anterior (head), posterior (tail) (e.g. dolphin).
• Bilateral animals actively move, are cephalized: have head tail left possess central nervous system or brain.

Porifera: Basal Taxon

• No true tissues.
• Sessile suspension feeders water drawn in through small pores in surface (ostia).
• Current created by choanocytes flagellated collar cells that absorb food.
• Water propelled central cavity (spongocoel), out osculum.
• Two layers with mesohyl between (gelatinous matrix interspersed with spicules = particles of silica or calcium carbonate).

Porifera

• Choanocytes engulf food particles by phagocytosis.
• Amoebocytes: absorb food from environment, from choanocytes digest, carry to other cells.
• Totipotent can turn into any other type of cell sponges can re-grow from fragments, asexual budding.
• Produce gametes; sponges are sequential hermaphroditesffirsthane one sex then other.

Arthropoda: Insecta

• Ants, wasps, bees, beetles, bugs, flies, mosquitoes, grasshoppers, crickets, dragonflies, butterflies, moths; mainly terrestrial predators, parasites, decomposers, prey, disease vectors.
• Air brought into tracheal system (respiratory) via spiracles (tiny holes in cuticle) like Kidney.
• Mouth parts can be modified for lapping up nutrients, sucking, piercing or chewing.
• Separate sexes; internal fertilization or external via sperm packet female picks up eggs laid on appropriate food source.
• Incomplete metamorphosis: young (nymphs) undergo series of molts until they reach larger, sexually mature adult stage.
• Wings modified from cuticle walking legs not lost possible exaptation evolved for thermoregulation
• Wing evolved first for