Diversity of Life: Plans Campbell’s ch 29, 30, 35—39 March 15—19, 2010

1. Diversity of Life: Plans Campbell’s ch 29, 30, 35—39March 15—19, 2010 • Describe the evolutionary relationships between cyanobacteria, single celled green algae, colonial green algae, multicellular green algae, bryophytes, pterophytes, gymnosperms, and angiosperms. Explain the evidence for these evolutionary relationships. • Compare and contrast the econiches of bryophytes, pterophytes, gymnosperms, and angiosperms. • Describe the similarities and differences in the alteration of generations lifestyle for single and multicellular green algae, bryophytes, pterophytes, gymnosperms, and angiosperms. Explain how differences in the lifecycles demonstrate fitness for different econiches. • List the unique challenges faced by terrestrial photoautotrophs, and explain how adaptations of each division of plants demonstrates fitness for these challenges. • Describe the structures of plants (each division) used for these functions, and explain how each of these structures functions: 1) transport & conservation of water & water soluble nutrients, 2) gas exchange, 3) support of body weight, 4) sexual & asexual reproduction, 5) energy acquisition , transport, & storage, 6) regulation & response/integration/cell communication, and 7) self-defense. • Discuss evidence that angiosperms have co-evolved with animals.

2. Eukaryotic Photoautotrophic via photosystems I & II Descendents of aquatic multicellular green algae Similar to multicellulargeen algae Chlorophyll b: primary photosynthetic pigment all plants Energy stored as starch Cell walls of cellulose in all Alteration of generations: 1n gametophyte + 2n sporophyte stages Sexual or asexual reproduction (mostly sexual) Different from multicellulargreen algae Multicellulargametophytes (in plants, not chlorophyta green algae) Terrestrial adaptations including: Only cells w/ flagella: sperm in bryophytes (moss) & pterophytes(ferns) Waxy cuticle covers surfaces to reduce water evaporation Stomata on leaves control gas exchange while minimizing water loss Multicellularsporophyte with specialized cells is dominant in all but mosses (diploidly prevents death due to mutations from UV radiation)

3. Gametophyte Sporophyte Seed gravitropism Cuticle Stomata photoperiodism thigmotropism Xylem Phloem Companion cells Seive tube element Meristem or cambium style Apical meristem stigma double fertilization fruit Lateral meristemdicot Primary growth monocot Secondary growth endosperm Cork cotyledon Archegonium transpiration Antheridiumradicle Megaspore mother cell pollen grain Microspore auxin (IAA) Nastic movements gibberllin Cytokininabscisic acid Ethylene phytochromePf,Pfr

4. Plants are evolutionary descendents of the chlorophyta (green algae). Charophytes are aquatic, but structurally very similar to plants (called the embryophytes). Of the sea weeds, only green algae have chlorophyll b and starch.

6. Evolutionary changes  fitness for terrestrial life • Multicelluarity & development of tissues & organs • Supporting more of body weight—lignin added to cellulose + secondary xylem w/ hard resins in large perinnealspecies • Gas exchange w/o photorespiration & w/o dessiccation—stomata in leaves open & close as the guard cells open/close • Prevention of desiccation of mature plant—hydrophobic waxy coating –cuticle—on surfaces • Prevention of desiccation of embryo—multicellular archegonia/embyro develops inside/water & food storing seeds in water resistant coats develop • Fertilization—swimming sperm replaced by windblown pollen in gymnosperm & pollinator animals in angiosperms • Delivery of water—development of roots & vascular tissue • UV radiation exposure—2n sporophytes become dominant • Adaptive radiation of herbivores—toxins, thorns, tough seed coats, etc. Seasonal control of reproduction, dormancy—Pr/PFr

7. Divisions (phyla) of plants—evolutionary trends: life on dry land; co-evolution with animals Bryophyta mosses, liverworts, hornworts (450 mya--adapted to moist, often shaded, regions) Pterophyta ferns (350 mya—dominant plants of Carboniferous--adapted to moist, often shaded, regions; can tolerate dry conditions except when sperm need to swim) Gymnospermae all cone bearing plants (300 mya--adapted to dry conditions--pangea, full sun) Angiospermae flower/fruit bearing plants (135 mya—dominant plants today—adapted to dry conditions, full sun; co-adapted with pollen distributing animals like insects)

8. Alteration of generations describes plant life cycles: Haploid Gametophyte (gamete producer) stage, and diploid sporopyte (spore producer) stage. Both stages can co-exist on the body of the plant, at least for part of all plant lifecycles.

9. Bryophytes (mosses, liverworts, hornworts)—most primitive existing plants. Bryophyte gametophytes (matt of the moss) are dominant (larger) to diploid sporophytes. Diploid spores from sporophytes germinate & divide by mitosis to produce mattlike moss gametophytes. Specialized sex organs develop—archegonium (akin to animal ovaries) & antheridia (akin to animal testes). Sperm swim to archegonia to fertilize eggs, then archegonia develop into sporophytes. Meiosis of some cells in sporophytes produces 1n spores.

10. Bryophytes—mosses, liverworts, hornworts Dominant gametophyte (1n) Gametophyte body (thallus) is short (<than 2 cm tall) & made of thin leaf/stem like structures; no roots—thin fibers attach it to surfaces like rocks Econiche—photoautotrophs in shady, damp regions UV radiation from sunlight indirect OR shielded by water covering plant surfaces Water & dissolved nutrients readily available via diffusion through the thin thallus/waste eliminated by diffusion through thallus Sperm can swim through water to fertilize eggs in the archegonia attached to the gametophyte

11. All other divisions (phyla) of plants have dominant 2n sporophytes. In ferns, tiny 1n gametophyte’s archegonia shield eggs fertilized by flagellated sperm swimming from antheridia. The sporophyte grows from the fertilized zygote in the archegonium by mitosis, then parts of it (sori, underside of leaves) undergo meiosis to produce 1n spores that germinate to form new gametophytes.

12. Cones of the gymnosperms contain 1n gametophytes. The larger structure (what we’d call the plant) is the 2n sporophyte. Megaspore mother cells in ovulate (female) cones undergo meiosis to form eggs, retained in female gametophytes (ovaries). Microsporangia meiosis pollen (sperm ) in pollen cones. Wind distributes gymnosperm pollen. Zygotes shielded in ovaries (seeds) develop by mitosis into sporophytes. Gymnosperms have no flagellated cells.