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

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

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

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

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