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pollen tube enter ovule through micropyle 4.pollen tube discharge sperm cells directly into embryo sac 5.faster-swimming sperm cell fuse with egg cell —> zygote —> embryo 6.slower sperm fuse with 2 nuclei of central cell (triple fusion) —> endosperm (food in seed) -double fertilization has been independently evolved 2 times (in Ephedra & anthophyta) -Traditional classification: monocots (monocotyledons) & dicots (dicotyledons) -dicot (only ~3% plants neither eudicots nor monocots) -Amborella (³Pč) -most primitive extant species: Amborella -Nymphaeales (!ÅK) -most primitive extant species: water lily -superior ovaries -Austrobaileyales (W éK) -include Illicium (ceD) -Magnoliids (W sÂ<) -include Magnolia (W D) -Eudicots (´=µ¡Â<) — 74% anthophyta -monocot: 24% anthophyta Structure developmental changes from flower —> fruitovaryfruitovuleseedovary wallpericarp (fruit wall)sperm cell + egg cell —> zygoteembryosperm cell + polar nucleiendospermintegumenttesta (seed coat)/20 66
BIOL1309 Notes-Evolutionary origin -Bennettitales -probably closest relationship -date: ~225 mya -earliest flower fossil: ~130 mya -Archaefructus -earliest fossil of flowering plant -1 pollen aperture (≈in Cycadophyta, Ginkgophyta, monocots) ***EudicotMonocotflowering partusually 4X / 5Xusually 3Xpollen apertures / furrows (sites for pollen tubes to grow)cotyledons (foliage leaves)21leaf venationusually net-likeusually parallelprimary vascular bundles in stemring formcomplex arrangement‘true’ secondary growthoften √Xeudicot & monocot adapt woody habit in a different way31/21 66
BIOL1309 NotesAnimalia -35 phyla, >1,000,000 extant species -best known phylum: Chordata (√all vertebrates) — 5% -95% — invertebrates Animalia (Invertebrate) -animals without backbone / other than vertebrae Porifera (Sponge) -5,000-10,000 extant species -filter feeder (suspension feeding) -mainly marine -outer part ‘water in’, inner part ‘water out’ from an opening -skeleton —> sponge -spicules: needle-like skeleton -silica / CaCO3(calcium carbonate) /22 66
BIOL1309 NotesAnimalia (Invertebrate) Phylum: Cnidaria -Main characteristics -~9,000 species -exclusively aquatic animals (mainly marine, some freshwater) -radial symmetry -circle of tentacles surrounding central mouth -tentacles used for food capture -similar body parts are arranged & repeated around a central axis -X head / front / back -life-form: polymorphism -polyp form (sessile) -medusa form (free-living / swimming) -alternating sequence of polyp & medusa -body structure — diploblastic (2 cell layers) -outer ectoderm -jelly-like mesoglea -inner endoderm -simple gut cavity -open @ 1 end form a mouth -no centralized brain -Unique characteristics -carnivores -cnidocytes — specialized stinging cells containing nematocysts -nematocysts -secretory structures -emit long threads explosively -for defense & food capture -on ectoderm, ^^ in tentacles -Class: Hydrozoan -mainly in polyp form -medusa phase is present only in some species -classification recently changed -small marine -paraphyletic -hydromedusae -<6cm diameter -velum (>±) along bell margin (distinguish feature with true jellyfish) -