Chapter 23 Glog

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Chapter 23 Glog

Chapter 23: Plant Evolution/ Diversity

23.1 THE GREEN ALGAL ANCESTOR OF PLANTS-Land plants evolved from a common ancestor with multicellular, freshwater algae which is evidenced because they both contain chlorophylls a and b, store excess carbohydrates as starch, and have cellulose in their walls-Adaptioms for successful colonization include protecting the embryo, apical growth, development of vascular tissue, development of megaphylls, dispersal of offspring by seeds, and the production of flowers-Reasons to adapt on land: more direct sunlight and more concentrated carbon dioxide for photosynthesis-the most successful land plants are those that protect all phases of reproduction from drying out-it is also crucial that land plants have efficient means of dispersing offspring on land- land plants also must be covered with a waxy cuticle to conserve water-in land plants, the zygotes developed into a multicellular 2n generation, and meiosis produces spores in multicellular sporangia. The gametophyte generation produces gametes within multicellular gametangia-spores undergo mitosis and become gametophytes 23.2 EVOLUTION OF BRYOPHYES: COLONIZATION OF LAND-the first plants to colonize land: the bryophytes (mosses, liverworts, and hornworts). They did not have true roots which need vascular tissue-bryophytes are covered by cuticles and have apical tissue that produces complex tissues- bryophytes are the only land animal whose gametophyte is dominant-bryophytes are usually short because they lack vascular tissue-an example of a bryophyte is moss. Moss is the largest phyla of the nonvascular plants. They generally grow in dark, damp enviornments. The three groups of mosses are peat, granite, and true. 23.3 EVOLUTION OF LYCOPHYTES: VASCULAR TISSUE-Vascular tissue trees can get very tall due to their ability to transport water and nutrients through xylem and phloem.-Xylem has cells called lignin which strengthens plant cell walls.-Cooksonia was one of the first vascular plants and when it branches, it was significant because instead of the single sporangium produced by a bryophyte, it produced many sporangium. 23.4 EVOLUTION OF PTERIDOPHYTES-Pteridophytes are seedless vascular plants that have megaphylls which allow plants to efficiently collect solar energy which allows more production of food and even offspring-An example of a pteridophyte is a fern. They generally live in warm, moist, tropical regions. Although some live in dry, rocky places. Fronds are the megaphylls of ferns which are divided into leaflets. The leaves are usually curled in a "fiddlehead" until they mature and open.they reproduce via windblown spores. 23.5 EVOLUTION OF SEED PLANTS: FULL ADAPTATION OF LAND-Seed plants are vascular plants that use seeds during the dispersal stage of their life cycle.-Seeds contain a sporophyte embryo and stored food within protective seed coats which allow embryos to survive harsh conditions.- Seed plants are dominant because not only are they heterosporous, but they also retain spores instead of releasing them into the environment.- An advantage is that no external water is needed for fertilization since whole male gametophytes (pollen) move to the female gametophytes- The two types of seed plants are angiosperms and gymnosperms.-Gymnosperms are mostly come bearing and their ovules are not completely enclosed by sporophyte tissue. There are four types of gymnosperms: conifers, chyads, ginkgoes, and gnetophytes.- An example of a conifer is an evergreen. Evergreens bear cones. They have tough, needle-like leaves of pines that conserve water via their thick cuticle and recessed stomata. They are monoecious.-Angiosperms are flowering plants. They live in a wide variety of enviornments and produce all fruits, vegetables, nuts, herbs, and grains. Most angiosperms are monocots or eudicots.- An example of an angiosperm is Apple trees. These trees have fruits which protect and aid in dispersal of seeds which can be done via win, Gravity, water, and animals.

Plants: multicellular, photosynthetic eukaryotesAlternation of generations: when an organism has two alternating forms in the course of its life cycleVascular tissue: specialized for the transport of water and organic nutrients throughout the body of a plant, also provides supportNonvascular plants: bryophytes that lack vascular tissueXylem: vascular tissue that carries waterPhloem: vascular tissue that carries nutrientsAngiosperms: flowering plantsGymnosperms: plants that reproduce via pollinationFruit: derived from an ovary, from angiospermsVascular system: allows land plants to stand tall and support expansive, broad leaves that efficiently collect sunlightSpore: a haploid reproductive cell that develops into new organism without the need to fuse with another reproductive cellStomata: little openings that allow gas exchange in plantsHomosporous: Plants that have spores that germinate into inconspicuous and independent gametophytes (Ground pines)Heterosporous: Plants have micros pores that develop into male gametophytes and megastores that develop into female gametophytes (seed plants)Megaphylls: broad leaves with several strands of vascular tissueMonoecious: when a single plant carries both make and female reproductive structures (conifers)Peduncle: flower stalk wich expands slightly at the tip of the receptacleReceptacle: bears sepals (protect the flower before it opens), petals (attract pollinators) stamens (help develop pollen grains) and carpels (contains the ovule) of the flower.





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