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Ch 24- Reproduction of Seed Plants Life Cycle of Gymnosperms – Reproduction takes place in cones- produced by mature sporophyte plant 2 types of cones-

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Presentation on theme: "Ch 24- Reproduction of Seed Plants Life Cycle of Gymnosperms – Reproduction takes place in cones- produced by mature sporophyte plant 2 types of cones-"— Presentation transcript:

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

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3 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

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5 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

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7 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

8 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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