Contrast the nutrition contained in the seed for the germinating embryo in gymnosperms and angiosperms including ploidy In both gymnosperms and angiosperms the seed provides nutrition to the developing embryo but the source composition and ploidy of the stored nutrients differ Gymnosperms Haploid n Angiosperms Triploid 3n Contrast the structures and ploidies of structures present in a mature ovule one in which there is a megagametophyte but before fertilization in gymnosperms and angiosperms Gymnosperms Integument Diploid 2n Outer protective layer becomes the seed coat after fertilization Megasporangium Nucellus Diploid 2n Nutritive tissue surrounding the megagametophyte Megagametophyte Female Gametophyte Haploid n Develops from the megaspore via mitosis Produces archegonia each containing an egg cell n angiosperms 1 Integument s Diploid 2n One or two layers develop into the seed coat 2 Megasporangium Nucellus Diploid 2n Reduced and usually absorbed by the developing embryo sac 3 Megagametophyte Embryo Sac Haploid n Contains 7 cells 8 nuclei including 1 Egg cell Haploid n 2 Synergids Haploid n help guide the pollen tube 3 Antipodal cells Haploid n function often unclear 1 Central cell with 2 polar nuclei Each nucleus haploid n Will fuse with a sperm to form triploid 3n endosperm Describe what it means for the following to germinate spore pollen grain seed Spore Spore develops into gametophyte A spore is a haploid 2n unicellular reproductive structure produced by plants fungi algae and some protists pollen grain A pollen grain is the male gametophyte of seed plants both gymnosperms and angiosperms Seed Seed contains an embryonic sporophyte A seed is a fertilized ovule containing a plant embryo food supply endosperm or cotyledons and a protective seed coat What factors stimulate seed germination Germination young sporophyte uses megagametophyte tissue as nutrition establishes root shoot system Nutrition allows sporophyte seedling to establish its roots shoot before it can photosynthesize What is a megasporangiate strobilus What is a microsporangiate strobilus How do they differ What are some other names for each structure Megasporangiate strobili produce seeds and are part of the female reproductive cycle called a female cone Microsporangiate strobili produce pollen and are part of the male reproductive cycle called a male cone How and in which structures does pollen develop in the microsporangiate strobilus Contrast this with pollen development in angiosperms Microsporangiate strobilus male cone Pollen is formed in the anther of the stamen male floral organ Microsporocytes 2n inside the microsporangia undergo meiosis produce microspores n Each microspore undergoes mitosis develops into a pollen grain immature male gametophyte What is the size of the pine microgametophyte when it is released Compare this to the size of the microgametophyte in angiosperms In gymnosperms like pine trees the microgametophyte pollen grain is multicellular and relatively large containing four cells at the time of release from the microsporangiate cone How is pollen dispersed in pines How does this relate to the amount of pollen produced Contrast this with the amount of pollen produced and how pollen in dispersed in angiosperms Conifers have wind dispersed pollen Randomness of pollen dispersal massive amounts of pollen released Most pollen grains lost or destroyed before they reach a megasporangiate strobilus Viable pine pollen found 60 miles 100 km from source trees 2000 ft 600 m up in air Describe the layers present from outside to inside in a pine seed including ploidy Explain how this represents 3 generations Seed coat from integument 2n Remains of megagametophyte n Embryo 2n