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Unformatted text preview: Midterm 2 Lecture 10 Chapter 29 (Pg 643-655) Green Plants How Do Biologists Study Green plants? • Biologists use three tools to understand how green plants originated and diversified: o Compare the fundamental morphological features of various green algae and green plants o Analyze the fossil record of the lineage o Assess similarities and differences in molecular traits such as the DNA sequences from selected genes Analyzing Morphological Traits • Phyla: several distinct groups and major lineages. • Similarities in morphological traits between land plants and green algae o Have chloroplasts with photosynthetic pigments chlorophyll a and b o Both contain thylakoids o Cell walls almost identical in composition o Both groups synthesize starch as a storage product o Peroxisomes and sperm are similar in structure and composition. • The two green algal groups that are most similar to land plants are Coleochaetales and Charales. • Land plants are broken up into three broad categories: nonvascular plants, seedless vascular plants, and seed plants. o Nonvascular plants: include the groups called liverworts, hornworts, and mosses. Liverworts and hornworts lack vascular tissue —meaning specialized groups of cells that conduct water or dissolved nutrients from one part of the plant body to another. o Seedless vascular plants: well-developed vascular tissue but do not make seeds. A seed consists of an embryo and a store of nutritive tissue, surrounded by a tough protective layer. Horsetails, ferns, lycophytes and whisk ferns are major types of seedless vascular plants o Seed plants: have vascular tissue and make seeds. Five major lineages in this group: cycads, ginkgoes, conifers, gnetophytes, and angiosperms. Gymnosperms: seeds do not develop in an enclosed structure. i.e. gnetophytes, cycads, ginkgoes, and conifers Flowering plants or angiosperms: seeds develop inside a protective structure called a carpel . Using the Fossil Record • First green plants that appeared in the fossil record: green algae in rocks that formed 700-725 million years ago • First land plants: found in rocks that are about 475 million years old. o Thus land plants are derived for green algae • The evolution of green algae contributed to the rise of oxygen levels on earth. • Five major events in the diversification of land plants: o Oldest occurred 475 million years ago and spans 65 million years. They consist of reproductive cells called spores and sheets of a waxy coating called cuticle....
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This note was uploaded on 04/07/2008 for the course BIO SCI 94 taught by Professor Carpenter during the Spring '05 term at UC Irvine.
- Spring '05