2 I. Kingdom Protista: Algae & Protozoa A. Characteristics1. Simple Eukaryotes – mostly single-celledAmoeba, slime molds, euglenoids, algae2. Organisms in this Kingdom don’t fitclearly into what we call plant, animal, orfungi.3. Most diverse eukaryotic Kingdom(>60,000 species).4. We are interested in this Kingdom becauseof the Chlorophytes & Charophyceans – greenalgae.
3 The line between Kingdom Protista and Kingdom Plantae is still being discussed…… Fig 29.4
5 B. Suspects and Evidence 1. Characteristics of Green Algae - Chlorophytesa. Mostly freshwater, but some are marine.b. Have plant-like chloroplasts.c. There are unicellular and multicellular formsd. Can live symbiotically with fungi as lichens
7 2. Characteristics of Green Algae - Charophyceans a. fresh water pondsb. They are considered to be the closest ancestors oftrue plants. Evidence:i. Both have same type of cellulose-synthesizingcomplexes in cell membraneii. Both have peroxisomes for enzyme storageiii. Both have same type of flagellated spermiv. Both form a cell plate during cell divisionv. Genetic evidence – charophyceans share agreater % of similar DNA with true plants than anyother algae
9 III. Plants Shared Characteristics A. Plants are multicellular eukaryotes that arephotosynthetic autotrophs.B. Shared pigmentsC. Cellulose cell wallsD. Store glucose as starchE. Etc.
10 IV. What challenges did plants face when they “moved” onto land? A. Issues Faced1. Acquire, transport, and conserve water2. Protect from UV radiation3. Resist pathogens (bacteria) and herbivores (later)4. Others?
15 a. 2 multicellular life stages: i. Sporophyte:* Diploid* Divides by meiosis to form spores* Spores – haploid cells that can grow into anew, multicellular, haploid organism (thegametophyte) without fusing to another cell.ii. Gametophyte:* Haploid* Divides by mitosis to form the gametes (eggand sperm)b. Egg & sperm fuse to form the diploid zygote, which divides by mitosis to form the sporophyte
16 3. Walled spores produced in sporangia a. Sporopollenin protects the spore from harsh environmental conditionsb. Sporangia = an organ within the sporophyte that produces the sporesc. Sporocytes = the diploid cells within the sporangia that divide by meiosis to form the haploid spores
18 4. Multicellular gametangia a. Gametangia = multicellular organs within thegametophyte that produce the gametes by mitosis.b. 2 types of gametangia:i. Archegonia – produce eggsii. Antheridia – produce spermc. Sperm travel to the egg, fertilizing it within thearchegonia.
20 5. Multicellular, dependent embryos a. After fertilization, the zygote remainswithin the archegonia, gaining nutrients forgrowth from the gametophyte.b. Zygote divides by mitosis to become thesporophyte.
21 6. Other examples of adaptations to life on land: (not all plants have the following): a. Cuticle – waxy covering to prevent desiccation µbial attackb. Secondary compounds – odors, toxins, tastes, etc. toattract pollinators and defend against herbivoresc. Roots - absorb water and minerals from the soild. Shoots - stems and leaves to make food.e. Stomata – openings in the leaf surface to allow gasexchange for photosynthesis and to regulate water loss.
22 f. Lignin in cell walls to provide structural support for shootsg. A vascular system that transports food & water fromroots to shoots and vice versa.
25 A. Nonvascular Land Plants: Bryophyta 1. Characteristicsa. Earliest land plantsb. Phyla: Hepatophyta – liverworts,Anthocerophyta – hornworts, and Bryophyta –mossesc. Inhabit most environments, including extremesd. Peat moss (sphagnum): doesn’t decay rapidly,stores 400 billion tons of carbone. Gametophyte is the dominant generation:
31 B. Vascular Plants 1. Characteristics a. Vascular tissue Xylem = water & mineral transport and Phloem = food (carbohydrates) transportb. Dominant generation = sporophytec. Sporophytes branched, independent of gametophyte parent
32 2. Groups a. Seedless Vascular Plants i. Characteristics Tiny gametophytes living just above or below soil surfaceEgg & Sperm need moist environment to fertilize (similar to bryophytes)
33 b. Two phyla of seedless vascular plants: i. Phylum Lycophyta (Club Mosses)They diverged first from bryophytes with an unbranched vascular system, flammable spore clouds, and were tree-like in the Carboniferous periodii. Phylum PterophytaWhisk ferns – no true leaves or rootsHorsetails – hollow air-filled stems (adaptation to water-logged,low O2 environment)Ferns – produce clusters (sori) of sporangia on underside ofleaves (fronds)
34 Phylum Lycophyta: club mosses, spike mosses, quill warts
37 d. Factors forest changes of the Carboniferous period (290-360 mya) i. Lycophytes (tree-like) & Pteridophytesii. First forestsiii. Swampy forests – slow decay in low O2, formeddeep layers of organic matteriv. Heat + pressure + time => coalv. Pulled lots of CO2 out of atmosphere, cooling theearth & forming glaciersvi. Larger species died out when climate becamedrier
38 3. Terrestrial Adaptations of Seed Plants a 3. Terrestrial Adaptations of Seed Plants a. Seeds replace spores as main means of dispersal.i. Why?ii. More resistant to harsh environ b/c multicellulariii. old way (ferns & mosses) = spores released fromsporangia to disperse and develop into gametophytesiv. new way: the sporophyte RETAINS its sporeswithin the sporangia & the tiny gametophytedevelops within the spore.
39 v. ovule = female sporangium + female spore. Female gametophyte develops within the spore &produces eggs.vi. after fertilization, the ovule becomes the seedvii. seed = sporophyte embryo + food supply (matureovule tissues)
40 b. Reduction of the gametophyte: Similar to Fig 30.2
41 c. Heterospory – separate male & female gametophytes i. Old way: sporangia spores bisexual gametophyte(antheridia sperm, archegonia eggs)ii. New way:Megasporangia megaspores female gametophyte eggsMicrosporangia microspores male gametophyte sperm
42 d. Ovules and seed production i. Megasporangia protected by layers of tissuecalled integuments.ii. Ovule = integuments, megasporangia, &megasporeiii. Megaspore female gametophyte egg &food supplyiv. After fertilization, embryo develops, ovulebecomes a seed
44 e. Pollen & Pollination i. Microsporangia microspores male gametophyte spermii. Pollen = male gametophyteiii. Pollination = transfer of pollen to ovule by windor animalsiv. Pollen tube brings sperm to egg within the ovule
45 4. Two types of seed plants: a. Gymnosperms i. CharacteristicsEvolved first and “Naked seed” – seeds develop on surface of specialized leaves called sporophyllsii. Four phyla:Ginkophyta – only Ginko bilobaCycadophyta – Cycads (look like palms)Gnetophyta – Gnetophytes (tropical trees)Coniferophyta – Conifers – cone-bearing treesDominate forests of the N. hemisphereMost are evergreenNeedle-shaped leaves to reduce water loss during drought
50 iii. Gymnosperm life cycle Fig 30.6iii. Gymnosperm life cycle
51 ii. One phylum: Anthophyta b. Angiospermsi. CharacteristicsFlowering plants, Most diverse, and Evolved from gymnosperms: Sporophylls rolled together to form ovaries.ii. One phylum: AnthophytaSeeds are enclosed in the moist reproductive tissue of thesporophyte generation (Ovary).More insects and animals for pollination, less dependenton wind.Formerly only 2 classes: monocots & dicots. Now 4clades (evolutionary lines):Basal angiosperms, Magnoliads, Monocots, & Eudicots
54 iii. Evolutionary success of Angiosperms Increased water transport efficiency due toimprovement in xylem tissue: tracheid cells, fibercells, vessel elements (gymnosperms only havetracheids)Flowers – attract pollinatorsFruits – many forms for variety of dispersalmechanisms
56 Notice the triploid stage! Each pollen grain (male gametophyte) produces two spermSperm travel down the pollen tube & into the ovule.Double fertilization – one sperm unites with the egg to form the 2n zygote, other sperm unites with the two nuclei of the female gametophyte to form a 3n endosperm – becomes food for the developing embryoOvule matures into the seed – contains sporophyte embryo & endosperm (food).Ovary (female sporangium tissues) matures into the fruit.
61 VI. Kingdom FungiFungi were once included in the plant kingdom because they produce spores, have cell walls, and are not animals.
62 A. Characteristics 1. Their cell walls do not contain cellulose (like plants), but do contain chitin(like insects, arthropods).2. Their bodies are filamentous.3. The organization of large structures such asmushrooms and morels is completely different from plants.4. They are heterotrophs (acquire nutrients by absorption).Hence the boot!!
68 3. Lichens: symbiotic association of cyanobacteria or green algae and fungi. a. Fungus provides shapeb. Algae provides food, N to the fungusc. Lichens are very sensitive to air pollution; used as indicators of air quality.
70 4. Mycorrhizae: mutualistic association of plant roots and fungi. a. Fungus increases the absorptive surface area of roots, increasing water and potassium uptakeb. Fungus receives food from the root exudates.