EOF NOTES FOR BIOLOGY 101 EXAM TWO Mosses and Ferns Evolution of land plants The oldest fosils are 425 mill years old this is 3 bill after the frst autotrophic cyanobacteria Special adaptations were required 1. A wacy cuticle help prevent the plant disuse from dieing out due to evaporation 2. Most plans possess multicellular sex organs called gametangia which protect the delicat gamets that they produce 3. To facilitate gas exchane tiny pores called stomata are present in the waxy cuticle 4. Antheriduim male 5. archegonia femal 6. In plans after fertilization the zygoe develops into a multicellular embro inside the achegonim thus the embro is protected during its development. 7. Ferns gymnosperms and angiosperms possess vascular tissues Tissues used for movement of materials throughout the plant body 8. Lignen Strengthening polymer found in the walls of cells that function for support and transport. 9. the vasculat tissue in these groups is arranged in specialized organs Roots Leaves Stems Mosses: dominant gametophyte Sporophyte dependent on the gametophyte No tru vascular tissue Get materials by capillary action and diffusion Flagellated sperm swim to the egg Ferns Dominant Sporophyte but gametophyte is independent Some vascular tissue Sperm swim to egg No seeds Gymnosperms Dominant sporophyte Much reduced gametophyte is dependent on the sporophyte vascular tussyes seeds produced but are not in fruit Angiosperms Dominant sporophyte Much reduced gametophyte is dependent on the sporophyte Vascular tissue Seeds are produced in the fruit Mosses General Mosses are limited to small size and moist enviorments because of the lack of vasculat tissue and the presence of flagellated sperm The haploid generation (gametophyte) is considered the dominant generation because it is capable of living independently of the diploid sporophyre in contras the moss sporophyte is attaché to and nutrionally dependent on the gametophyte. Sexual cycle Spore (N) germinated by mitosis to form a small green threadlike structure which resembles a green algae the proonema(thread like structure) continues to grow groth contiues to form the mature gametophyte(n) mature gametophyte(n) containg the gametangia the male antheridium and the female archegonium. Most mosses have a separate male and female gametophyte. Sperm is produced by the antheridium by mitosis eggs also haploid a also produced by mitosis Sperm swim through a film of moisture to the archegonuim and fertalize the egg This formas a zygote that is diplod (sn) the zygote divides by mitosis and develps into an embryotic sporophyte the sposophyte (2n) grows a stalk and emerges from the archegonum but remains attaché to and ddependent on the gametophyte(n) At the tip of the sporophyte stalk is the sporangium(2n) This contains sporocys mother cells which are also diploid Basicly it?s a sporangium on a stick The sporangium cells 2n undergo miosis to make spored when the spores are ready they are released Wind or rain despers them the cyce then starts over Ferns General Fernas have tru vascular tissue Roots Stems Leaves The fern sporophyte is composed of a horizontal underground stem the fern gametophyte is also free living it is a tiny green heart shaped structure that grows flat against the ground The fern gametophyte lacks vasculat tissue and has tiny hair like absorptive rhizoids that anchor it This usually makes archigonium and antheridium the sporophyte generation is dominant not only because it is larger than the gametophyte but also because it persists for an extended peropid of time where ass the gametophyre dies soon after reproducing ferns can reproduce asexually as well as sexuailly Sexual reproducution Spores n settle in a favorable plance and germintate groth by mistosis results in the formation of the gametophyte n the mature gametophyte is called the prothalllus this is green independent but short lived gametangium are both produced here inside the antheridua and aregonia sperm n and eggs n are produced by mitosis the sperm are vvery large and have many flagella the sperm swim to the archegonium where they fertilize the egg forming the zygote 2n the zygote grows by mitosis into the sporophyte 2n on the mature sporophyte sporangium develpp on top of the fronds spore mother cells in the sporangium undergo meiosis to form 4 n spored the sporangium burst open relesing thits insides. Gymnosperms Homspoy vs heterospory 1. In the life cycles examined thus far (mosses and ferns) plants only produce one type of spore as a result of meiosis. These spores are produced by the sporophyte 2. These spores then produce only one type of gametophyte on which will develop the gametangia(archegonia antheriium) This condino is know as homospory 3. In the higher plants the gymnosperms and angiosperms two types of spores are produced by two different sypes of sporangium Micrspores Male spores Microsporocyles contained within the microsporangium Megaspores 4.This condision is known as heterotrophy 5. production of two different types of spores and the resulting two different
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