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Ch 24- Reproduction of Seed Plants

Ch 24- Reproduction of Seed Plants. Life Cycle of Gymnosperms Reproduction takes place in cones- produced by mature sporophyte plant 2 types of cones- pollen cones and seed cones Pollen- male Seed- female Ovules- base of seed cone where female gametophytes develop

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Ch 24- Reproduction of Seed Plants

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  1. Ch 24- Reproduction of Seed Plants • Life Cycle of Gymnosperms • Reproduction takes place in cones- produced by mature sporophyte plant • 2 types of cones- pollen cones and seed cones • Pollen- male • Seed- female • Ovules- base of seed cone where female gametophytes develop • Pollen tube- structure that contains 2 haploid sperm nuclei, one sperm disintegrates and other fertilizes egg

  2. Structure of Flowers • Flowers are reproductive organs- composed of sepals, petals, stamens, and carpels • Sepals- outermost circle of flower parts, encloses bud, protects the flower while it is developing • Petals- brightly colored structure just inside the sepals, attracts insects and other pollinators • Stamen- male part of flower, made up of anther and filament • Filament-long, thin structure that supports an anther • Anther- flower structure where haploid male gametophytes are produced • Carpels- innermost part of flower that produces female gametophyte • Ovary- contains ovules from which female gametophytes are produced • Style- narrow stalk of the carpel in flower • Stigma- sticky portion at top of style where pollen grains land

  3. Life Cycle of Angiosperms • Reproduction takes place within flower- the seeds develop inside protective structures following pollination and fertilization • Most gymnosperms and some gymnosperms are wind pollinated • Most angiosperms are pollinated by animals • Fertilization in angiosperms • One sperm fuses with egg to form zygote • Second sperm fuses with two polar nuclei to form endosperm- food rich tissue that nourishes the seed • Double fertilization

  4. Sec 2- Seed Development/Germination • What is a fruit? • Ripened ovary that contains angiosperm seeds, any seed that is enclosed within its embryo wall • As angiosperm seeds mature, ovary walls thicken to form fruit • Apples, grapes, strawberries • Peas, corn, rice

  5. How are seeds dispersed? • By animals, wind, water • What type of seeds are dispersed by animals? By wind and water? • What factors influence dormancy and germination? • Temperature and moisture • Dormancy- period where plant is alive but not growing • Varies between plants • Germination- early growth stage of plant embryo • Seed absorbs water causing it to swell and crack open

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