Plant APBio

Slide 1: Chapter 21 The Plant Kingdom

Slide 2: Chapter 21 2 Key Features of Plants Multicellularity Ability to photosynthesize (most) Exhibit alternation of generations (a multicellular diploid generation alternates with a multicellular haploid generation)

Slide 3: Chapter 21 3 Alternation of Generations Diploid sporophyte plant produces haploid spores through meiosis Spores divide by mitosis and develop into haploid gametophyte plants Haploid gametophyte plant produces haploid gametes through mitosis Gametes fuse to form diploid zygotes, which divide by mitosis and develop into diploid sporophytes

Slide 4: Alternation of Generations Chapter 21 4 in Plants Gameto- Gametophytes form by meiosis Spores form phyte by meiosis 2n n Sperm n Gametes meet Spores Egg & fuse to form n n n n zygote 2n 2n Zygote Spore Haploid Diploid Mother Cell 2n Sporo- Embryo phyte 2n

Slide 5: Chapter 21 5 Evolution of Plants The evolutionary origin of plants • Division Rhodophyta—red algae • Division Phaeophyta—brown algae • Division Chlorophyta—green algae and the origin of land plants

Slide 6: Chapter 21 6 Green Algae Several lines of evidence support the hypothesis that green algae gave rise to plants DNA comparisons show that green algae are plants’ closest living relatives Both use the same type of chlorophyll and accessory pigments in photosynthesis Both store food as starch Both have cell walls made of cellulose

Slide 7: Chapter 21 7 Fresh Water Ancestors Most green algae live in fresh water, suggesting that early plants evolved in freshwater habitats Early green algae must have evolved characteristics to withstand the challenges of fresh water habitats, e.g. temperature extremes, periods of dryness These adaptations provided a foundation for descendants to evolve traits for life on land

Slide 8: Chapter 21 8 The Evolution of Land Plants Roots and rootlike structures (anchor & absorb) Vascular tissue for transport of water & nutrients Stiffening substance (lignin) for support Waxy covering (cuticle) limits evaporation Stomatal pores • Mediate gas exchange • Regulate water vapor loss Evolutionary adaptations in plant reproduction • Early algae relied on water currents for fertilization • Dry land adaptation include the generation of pollen, seeds, flowers, and fruit… • Adaptations in the alternation of generations…

Slide 9: Chapter 21 9 Reproduction Without Water Pollen • A reduced male gametophyte that allows wind (instead of water) to carry sperm to eggs Seeds • Nourish, protect, and help disperse developing embryos Flowers • Attract pollinators Fruits • Attract animals to disperse seeds

Slide 10: Chapter 21 10 Major Groups of Plants Bryophytes (nonvascular plants) • Lack well-developed structures for conducting water and nutrients Tracheophytes (Vascular plants ) • Have a complex vascular system

Slide 11: Tracheophytes Chapter 21 11 Bryophytes Seed Plants Liver- Mosses Ferns Gymno- sperms Angio- worts sperms Evolutionary Tree of Major Flowers & Plant Fruits appear Groups True vascular tissue & lignin appear Seeds and Ancestral pollen appear Algae

Slide 12: Chapter 21 12 The Bryophytes Nonvascular plants No true roots, leaves, and stems Still require a moist environment Anchoring rhizoids absorb water & nutrients Reproductive structures protect gametes Still depend on water for fertilization Dominant gametophyte generation

Slide 13: Chapter 21 13 Liverworts & Mosses Female Archegonium Liverworts Gametophyte Mosses Sporophytes Female (a) (b) Gametophytes

Slide 14: Chapter 21 14 The Bryophytes: Reproduction Gametes develop within protected structures on gametophyte • Archegonia (singular, archegonium) produce eggs • Antheridia (singular, antheridium) produce sperm • Archegonia and antheridia may be located on the same plant or on different plants

Slide 15: Sporophyte Chapter 21 15 si s Capsule Mei o Life Old Cycle Gametophyte of a Moss Haploid spores liberated (a) from sporophyte capsule Spores disperse and germinate Zygote develops into sporophyte within Diploid gametophyte 2n Haploid Fertilization 1n

Slide 16: Spore germinates Chapter 21 16 into gametophyte Fertilization Archegonium produces egg Sperm swim to egg Antheridium produces sperm Leafy Life Gametophyte Cycle of a Diploid Moss 2n (b) Haploid 1n

Slide 17: Chapter 21 17 The Vascular Plants Have roots, stems, and leaves Have vessels impregnated with the stiffening agent lignin Sporophyte generation is dominant Include the seedless vascular plants and the seed plants

Slide 18: Division Tracheophyta: Chapter 21 18 Vascular Plants Adapted to life in drier conditions • Had to generate body support • Vessels to conduct water and nutrients • A stiffening substance called lignin Seedless plants: club mosses, horsetails, and ferns • Sporophyte generation more dominant • Fertilization still relies on water

Slide 19: Life Cycle of Chapter 21 19 Sporophyte Ferns (a) Sporangium Masses of Sporangia sis Stem M eio Root Sporophyte develops from gametophyte Gametophyte Haploid spores liberated Diploid from sporangium 2n Haploid 1n

Slide 20: Chapter 21 20 Life Cycle of Ferns (b) Fertilization Archegonium Haploid spores liberated produces egg from sporangium Spores disperse & germinate Sperm swim to egg Gametophyte Antheridium produces sperm Diploid 2n Haploid 1n

Slide 21: Chapter 21 21 Seedless Plants Club Mosses Horsetails Ferns

Slide 22: Seed Plants: Chapter 21 22 General Dominance of the sporophyte generation Reproductive adaptations • Pollen – Wind and pollinators for fertilization – Water not required for fertilization • Seeds – Stores food for embryo – Embryo protection for unfavorable environments

Slide 23: Chapter 21 23 Seeds (b) Angiosperm Seed Coat Stored Food Embryo (c) Wind Dispersal (a) Gymnosperm (d) Water Dispersal

Slide 24: Seed Plants: Chapter 21 24 Gymnosperms Nonflowering seed plants Produce "naked seeds" Three divisions: • Coniferophyta • Cycadophyta • Ginkgophyta Conifers are adapted to dry, cold conditions • Thin, waterproof needles to decrease evaporation • Evergreen; year-round photosynthesis • Produce an "antifreeze" substance in sap

Slide 25: (b) A Cycad – either Chapter 21 25 male or female Two Uncommon Gymnosperms (a) Gingko

Slide 26: Chapter 21 26 Gymnosperms: Conifers Adapted to dry, cold conditions: • Retain green leaves throughout the year (evergreen) • Thin, needle-like leaves covered with waterproofing material to reduce evaporation • Produce an “antifreeze” in sap

Slide 27: Male Female Chapter 21 27 Cone Cone Female Life Scale Cycle of Ovule the Pine Mature Male (a) Sporophyte Scale SIS MEIO Seedlings Spore-forming (Sporophyte) S Cell MEIOSI Haploid 1n Male gametophytes Diploid (pollen) liberated 2n

Slide 28: Life Cycle of the Pine (b) Chapter 21 28 OSIS MEI Seedlings (Sporophyte) S ME IOSI Female Gametophyte Pollen liberated; Dispersed by wind Pollen lands on Seed female scale Pollen Egg Cell Tube Haploid Embryo 1n Diploid FERTILIZATION 2n

Slide 29: Seed Plants: Chapter 21 29 Angiosperms Flowering seed plants The dominant plant form on Earth Major evolutionary adaptations • Flowers to attract pollinators • Fruit to protect seeds and developing embryo • Broad leaves – Increase photosynthesis during the growing season – Shed during periods of cold and drought

Slide 30: Chapter 21 30 Monocot vs Dicot Class Monocotyledoneae (monocots): grasses, grains, corn 1 cotyledon leave veins in parallel lines Flower parts, in multiple of 3 scattered vascular bundles Class Dicotyledoneae (dicots): hardwood trees, shrubs, and herbs 2 cotyledons, web-like veins, flower petals in 4/5s, ringed vascular bundles

Slide 31: Chapter 21 31

Slide 32: Chapter 21 32 Flowers Flowers are reproductive structures in which both male and female gametophytes are formed Believed to have evolved when gymnosperm ancestors formed an association with animals • Animals benefited by eating some of the protein- rich pollen • Plants benefited by using animals as pollinators Most flowers are showy and attract animal pollinators (e.g. insects)

Slide 33: Flower Chapter 21 33 Seedling Anther Ovary Food Ovule Embryo Seed Coat Seed Spore-forming Cell MEIOSIS Diploid Fruit 2n Life Cycle of a Haploid Flowering Plant (a) 1n

Slide 34: Life Cycle of a Flowering Plant Chapter 21 (b) 34 Pollen (male MEIOSIS gametophyte) SIS Fruit MEIO Stigma Female Gametophyte ION ZAT Spore TILI FER Pollen Tube Diploid 2n Sperm Egg Cell Haploid Nuclei 1n

Slide 35: Chapter 21 35 Fruits Encourage Seed Dispersal Fruits are mature ovaries that contain developing seeds Various fruit adaptations help disperse seeds • Edible fruits entice animals to eat them (seeds pass through digestive tract unharmed) • Burrs cling to animal fur • Winged fruits are carried through the air

Slide 36: Chapter 21 36 Broad Leaves Broad leaves of angiosperms collect more sunlight for photosynthesis than narrow leaves of gymnosperms Temperate angiosperms drop leaves to conserve water when it is in short supply (fall, winter) Tropical and subtropical angiosperms are evergreen • May shed leaves during dry season

Slide 37: Chapter 21 37 Broad Leaves Photosynthetic advantage is offset by fact that broad, tender leaves are more appealing to herbivores than tough, waxy needles of conifers Angiosperm defenses include • Physical defenses (thorns, spines, resins) • Chemical defenses (make plant tissue poisonous or distasteful)

Slide 38: Chapter 21 38 Crucial Ecological Role Through photosynthesis, plants provide food, directly or indirectly, for all of the animals, fungi, and non-photosynthetic microbes on land Plants produce oxygen gas as a byproduct of photosynthesis, continually replenishing oxygen in the atmosphere

Slide 39: Chapter 21 39 Crucial Ecological Role Plants help create and maintain soil • Dead plant material is decomposed by fungi, prokaryotes, and other decomposers • Decomposed plant tissue becomes part of the soil, making it more fertile • Roots of living plants help hold soil together, preventing erosion by wind and water

Slide 40: Chapter 21 40 Human Necessities and Luxuries Plants provide shelter • Wood is used to construct housing Plants provide fuel • Wood: important fuel for warming and cooking in many parts of the world • Coal: derived from the remains of ancient plants that have been transformed by geological processes

Slide 41: Chapter 21 41 Human Necessities and Luxuries Plants provide medicine • Many medicines and drugs were originally found in and extracted from plants, e.g. aspirin, Taxol, morphine Plants provide pleasure • Flowers, gardens, and lawns • Coffee, tea, and wine

Slide 42: Chapter 21 The End