Presentation on theme: "Chapter 29 Seedless Plants: Bryophytes and Ferns"— Presentation transcript:
1 Chapter 29 Seedless Plants: Bryophytes and Ferns AP BiologyChapter 29Seedless Plants: Bryophytes and Ferns
2 Objectives1. Name the protist group from which plants are hypothesized to have descended, and describe supporting evidence.2. Discuss some environmental challenges of living on land, and describe how several adaptations meet these challenges.3. Summarize the features that distinguish bryophytes from green algae and from other plants.4. Name and briefly describe the three phyla of bryophytes.
3 Algae Plantlike (autotrophic) protists Unicellular or Colonial Aquatic (live in water)The Chlorophytes (green algae) appear to be ancestral to the plants
5 Terrestrial (Land) Plants The move from aquatic habitat to land creates a number of problems:Protection against dryingTransport of sperm to eggStructural supportPlants that have specialized adaptations to solve these problems can live in drier environments, while those that do not are restricted to moist environments
6 Protection against drying Water loss in plants is called TranspirationTerrestrial plants are protected against transpiration by:EpidermisWaxy “cuticle”Stomata
7 Transport of sperm to egg Algae and aquatic plants, since they live in water, have a natural unbroken water pathway for sperm to swim to the eggSeedless plants can only reproduce sexually under moist conditions. The “gametophyte” is low to the ground and only grows in moist habitatsSeed plants are less restricted because they provide an internal water pathway in a specialized “pollen tube”
8 Structural SupportAlgae and aquatic plants are supported by the buoyancy of the water they live in.Bryophytes, which lack strong supportive tissues, are very small and low to the groundTracheophytes, supported by a series of hollow tubes with thickened cell walls, can grow much taller
10 Distinguishing Plants from Algae Alternation of GenerationsMulticellular, dependent embryoWalled spores produced in sporangiaMulticellular gametangiaApical meristemsSee pages in textbook
11 Alternation of Generations Gametophyte (n) produces gametes (n)Gametes fuse to form zygote (2n)Zygote develops into a dependent, multicellular embryo (2n)Embryo grow into the sporophyte (2n)Sporophyte produces spores (n) by meiosisSpores grow and develop forming the gametophyte (n)
12 Multicellular EmbryoThe zygote will develop into an embryo within the parent plantThe parent provides protection and nourishment
13 Spores and SporangiaHaploid spores will be produced in specialized organs on the sporophyte generation plant called sporangiaThe spores are protected by a protective wall
14 Gametangia (produce gametes) Moss Archegonium – Note the mature eggsMoss Antheridium – will producesperm cells
15 Apical MeristemGrowth of multicellular organisms begins with cells that have not yet differentiated.In plants, undifferentiated tissue is called meristem.Meristem tissue at the tip (apex) of a root or shoot is “apical” meristem
16 Bryophytes Lack vascular tissue Reproduce with spores Mosses Liverworts
18 Bryophyte ClassesHornwortsLiverwortsMossesSee page 608 in Textbook
19 Objectives5. Describe the life cycle of mosses, and compare their gametophyte and sporophyte generations.6. Discuss the features that distinguish ferns and other seedless vascular plants from algae and bryophytes.7. Describe the life cycle of ferns, and compare their sporophyte and gametophyte generations.8. Compare the generalized life cycles of homosporous and heterosporous plants.9. Name and briefly describe the four phyla of seedless vascular plants.
21 Mosses – Comparing generations Sporophyte GenerationTemporaryDependent upon the gametophyteTaller, grows from the top of the gametophyteNot photosyntheticGametophyte GenerationPermanent/Long livedIndependentShorter, grows from the soil/anchored with rhizoidsPhotosynthetic
22 Tracheophytes – Vascular plants Vascular tissue provides advantagesEfficient transport of water and nutrientsStructural support
23 Tracheophyte phylogeny Tracheophytes include all plants with vascular tissueThe tracheophytes are subdivided into seedless plants and seed plantsSeed plants are subdivided into gymnosperms and angiosperms (flowering plants)
24 Vascular Seedless Plants Ferns and HorsetailsHave vascular tissueReproduce with Spores
25 Fern Life CycleThe gametophyte generation is small, flat and nonvascular, resembling a liverwortThe gametophyte dies once the sporophyte is establishedThe sporophyte is the prominent generationVascularLong lived
26 Ferns – Comparing Generations SporophytePermanent/Long livedIndependent once establishedProduces a rhizome for storage and asexual reproductionForms “fronds”GametophyteTemporary, dies once the sporophyte is establishedNonvascular, small and low to the groundResembles liverwortFlattened form captures and holds water
27 Homosporous and Heterosporous Homosporous PlantsMost seedless vascular plantsSingle type of sporeSpores give rise to monoecious (bisexual) gametophytesHeterosporous PlantsAll seed plants and some seedless vascular plantsTwo types of sporangia, each producing a different type of sporeMegaspores give rise to the female gametophyteMicrospores give rise to the male gametophyte
28 Seedless Vascular Plants LycophytesMost ancient group of vascular plants“club mosses” and “spike mosses”Superficially resemble mosses, but vascularWhisk FernsBranching stems, but no rootsHorsetailsPhotosynthetic stems with rings of branches or small leavesFernsHorizontal stems with large “fronds” divided into leaflets
33 Chapter 30 Seed Plants: Gymnosperms and Angiosperms AP BiologyChapter 30Seed Plants: Gymnosperms and Angiosperms
34 Chapter 30 Objectives1. Compare the features of seeds with those of spores and discuss the advantages of plants that reproduce primarily by seeds rather than by spores. 2. Trace the steps in the life cycle of a pine, and compare its sporophyte and gametophyte generations. 3. Summarize the features that distinguish gymnosperms from bryophytes and ferns. 4. Name and briefly describe the four phyla of gymnosperms.
35 Seed Plants Seeds provide many advantages over spores Multicellular embryoStored foodProtectionMechanisms for dispersalFlowering Plants – Apple seedsConifers – Pine seeds
36 Life Cycle TrendsAlternation of generations continues in the seed plants, but the gametophyte is diminished to the point of being microscopicBy enclosing the gametophyte entirely within the sporangium, the need for a film of water for transport of sperm is eliminated. The pathway is fully enclosed.Motility in sperm is lost in most seed plants and diminished in others
37 Life Cycle of the Pine The Pine tree is the sporophyte generation Gymnosperms are heterosporous. The megasporangium is located in an ovulate cone. The microsporangium is in a pollen cone.The female gametophyte develops entirely within the megasporangiumThe male gametophyte is enclosed within the pollen grain
39 MicrosporangiumThe pollen cone contains microsporangia, which will produce the pollen grainsThe male gametophyte is within the pollen grain
40 Megasporangium The ovulate cone contains the megasporangium The female gametophyte is enclosed within itPollination results in the growth of a pollen tube into the ovule, directly depositing a sperm cell
42 Evolutionary significance The gymnosperms had advantages over seedless plants:With the gametophyte protected and sperm delivered directly by the pollen tube, gymnosperms were able to survive in much drier environments than any of the seedless plants.The climate became drier in the Mesozoic, giving the advantage not only to the gymnosperms, but also to the reptiles over the amphibians
43 Concept check 30.1 p. 621Contrast sperm delivery in seedless plants with sperm delivery in seed plantsWhat features not present in seedless plants have contributed to the enourmous success of seed plants on land?If a seed could not enter dormancy, how might that affect the embryo’s transport or survival?
44 Gymnosperms Vascular, seed producing plants “naked seed” – seeds are not completely enclosed by the ripened ovaryGenerally have needle-like (pines) or scale-like (cedars) leaves
45 Gymnosperm Phylogeny (p. 622-3) CycadsResemble palms, but are gymnosperms. The cycads were the prominent large plants of the mesozoicGnetophytesGinkgoesA deciduous gymnosperm, only one species still existsConifersPines, spruce, redwoods The most diverse group of gymnosperms
46 Chapter 30 Objectives5. Summarize the features that distinguish flowering plants from other plants 6. Diagram the parts of a flower. Describe the structure and function of each part 7. Briefly explain the life cycle of a flowering plant and describe double fertilization.
47 Angiosperms (Flowering Plants) Vascular seed plantsHave a wide variety of adaptations for transferring pollenSeeds mature inside of the ripened ovary of the flower, forming “fruit” which protects, nourishes, and aids dispersal of the seeds
50 Double FertilizationDouble fertilization occurs only in the angiospermsThe pollen grain will produce 2 sperm cells, one which will fertilize the egg to form the zygote (2n) and another which will fertilize the diploid female gametophyte, producing a triploid cell which will form the endosperm
51 The Endosperm and Cotyledons The endosperm contains stored food (mostly starch) which will contribute to the early growth of the embryoThe endosperm will form either 1 or 2 seed leaves called cotyledonsAngiosperms are categorized as either monocots or dicots based on the number of cotyledons
53 Chapter 30 Objectives8. Define fruit. Discuss adaptive advantages of fruits. Give examples 9. Contrast dicots and monocots, the two classes of flowering plants. 10. Discuss the evolutionary adaptations of flowering plants. 11. Summarize the evolution of gymnosperms from seedless vascular plants, and trace the evolution of flowering plants from gymnosperms
54 Fruit Fruit is the ripened ovary of a flower Fruit may contain stored food and moistureFruit provides a mechanism for seed dispersal
57 Advantages of Flowering Plants Many flowering plants attract animal pollinators, which increase the likelihood of pollen grains actually resulting in pollinationSeeds of flowering plants contain far more stored food than the seeds of gymnosperms. The endosperm provides for rapid growth of the embryo after germinationFruit facilitates seed dispersal through a wide variety of mechanisms: wind, water, animals
58 Trends in Plant Evolution Animal pollinators greatly increase the rate of cross-pollination, which in turn increases the amount of genetic recombination and variation that occurs within a speciesGreater variation results in both more opportunities for adaptation and a more rapid rate of evolutionThe connection between flower and pollinator results in co-evolution. The flower and the pollinator both evolve in relation to each other
59 Pollinator/Flower Coevolution Wasp mimicryh8I3cqpgnAThe hoverflyRI9oOverdramatic artistic pollinator representation
60 Concept Check 30.3 p. 632It has been said that an oak is an acorn’s way of making more acorns. Write an explanation that includes these terms: Sporophyte, gametophyte, ovule, seed, ovary and fruitCompare and contrast a pine cone and a flower in terms of structure and function
61 Concept Check 30.3 p. 6323. Do speciation rates in closely related clades of flowering plants show that flower shape is correlated with the rate at which new species form, or that flower shape is responsible for this rate? Explain.