Biology 1442 week 2 of notes for exam 2
Biology 1442 week 2 of notes for exam 2 BIOL 1442
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This 3 page Class Notes was uploaded by Kristin O'Flaherty on Wednesday March 9, 2016. The Class Notes belongs to BIOL 1442 at University of Texas at Arlington taught by Dr. Roelke in Winter 2016. Since its upload, it has received 167 views. For similar materials see Evolution and Ecology in Biology at University of Texas at Arlington.
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Date Created: 03/09/16
2/29 CH 29 How plants colonized the land the terrestrial surface was lifeless cyanobacteria and protists show up on land plants have diversified into roughly 290,000 species plants are defined as having terrestrial ancestors land plants do not include photosynthetic protists plants supply oxygen and are the ultimate source of most food green algae called charophytes are the closest relatives of land plants*********** lots of characteristics appear in some algae o rings of cellulosesynthesizers o have sperm that swim both nuclear and chloroplast genes point to charophytes as the closest living relatives of land plants sporopollenin is a layer of a durable polymer that prevents charophytes and zygotes from drying out also found in spore walls land plants diversified as adaptations evolved that enabled them to thrive despite challenges the placement of the boundary dividing land plants from algae is the subject of ongoing debate until this debate is resolved, we define plants as embryophytes plants with embryos alternation of generations o gametophytehaploid and produces gametes o sporophyte produces spores multicellular dependent embryos o see both the parent and the embryo in a seed Walled spores produced in sporangia o the sporophyte produces spores in organs called sporangia o diploid cells called sporocytes undergo meiosis to generate haploid cells o sporopollenin Multicellular Gametangia o female archegonia o male antheridia apical meristems o in the roots cuticle waxy covering of epidermis stomata cells that allow for gas exchange plants on land are at least 470 million years old land plants can be categorized by the presence of vascular tissue THERE WILL BE AT LEAST ONE QUESTION ABOUT ONE OF THE LIFE CYCLES (SOMETHING MAJOR) Importance of mosses o help retain nitrogen 3/2 giant lycophyte trees thrived for millions of years in moist swamps ferns are the most widespread seedless vascular plants with more than 12,000 species horsetails were but now only have one genus CH 30 a seed consists of an embryo with a coat of nutrients seed plants have o reduced gametophytes o heterospory o ovules o pollen the gametophytes develop within the wall of spores look at plant group table Heterospory ancestor seed plants were likely homosporous Megasporangia produce megaspores that give rise to female gametophytes microsporangia produce microspores that give rise to male gametophytes ovule is a megasporangium, megaspore, and one or more protective integuments microspores develop into pollen grain pollination is the transfer of pollen to the part of a seed plant containing ovules pollen eliminates that need for a film of water a seed develops from the whole ovule is a sporophyte embryo along with its food supply, packaged in a protective coat seeds provide some evolutionary advantages over spores gymnosperms means “naked seeds” seeds are exposed on cones angiosperms are fruits which are mature ovaries BETWEEN 3 AND 6 QUESTIONS ON THE DIFFERENT LIFE CYCLES OF PLANTS life cycle of a pine: o 3 key features are miniaturization of their gametophytes, o development of seeds from fertilized ovules o the transfer of sperm to ovules by pollen pine tree is the sporophyte and produces sporangia in male and female cones some plants begin to develop these modern features in the Devonian period gymnosperms start early in the fossil record about 305 million years ago gymnosperms were better suited to drier conditions than nonvascular plants served as food for herbivores insects started pollinating over 100 million years ago angiosperms ended up replacing gymnosperms angiosperms now dominate though conifers still dominate some regions gymnosperms have 4 phyla o cycadophyta flagellated sperm, palm like leaves o gingkophyta flagellated sperm, high tolerance to air pollution o gnetophyta vary in appearance, live in tropics or in deserts o coniferophyta largest of the gymnosperm phyla, evergreens angiosperms are seed plants with reproductive structures called flowers and fruits they are the most widespread and diverse of all plants all angiosperms are classified in a single phylum, Anthophyta two key adaptations o flowers o fruits flower is an angiosperm structure specialized for sexual reproduction pollinated by insects or animals or wind flower is specialized shoot with up to four types of modified leaves o sepals, enclose the flower o petals, attract the pollinators o stamens, produce pollen o carpels, produce ovules