29_Lectures_2008_Class

29_Lectures_2008_Class - Chapter 29 Plant Diversity I How...

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Chapter 29 Plant Diversity I How Plants Colonized Land
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Key Concepts 29.1 Land plants evolved from green algae 29.2 Mosses and other nonvascular plants have life cycles dominated by gametophytes 29.3 Ferns and other seedless vascular plants were the first plants to grow tall
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Mauna Loa Monthly Mean Atmospheric CO 2 Keeling Curve” Keeling Curve”
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Overview: The Greening of Earth Looking at a lush landscape, it is difficult to imagine the land without any plants or other organisms For more than the first 3 billion years of Earth’s history, the terrestrial surface was lifeless Since colonizing land, plants have diversified into roughly 290,000 living species
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Overview: The Greening of Earth
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Concept 29.1: Land plants evolved from green algae Green algae called charophyceans are the closest relatives of land plants 40 µm 5 mm Chara species, a pond organism Coleochaete orbicularis, a disk-shaped charophyte that also lives in ponds (LM )
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Morphological and Biochemical Evidence Many characteristics of land plants also appear in a variety of algal clades, mainly algae However, land plants share four key traits only with charophyceans: 1. Rose-shaped complexes for cellulose synthesis
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Morphological and Biochemical Evidence
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Morphological and Biochemical Evidence Many characteristics of land plants also appear in a variety of algal clades, mainly algae However, land plants share four key traits only with charophyceans: 1. Rose-shaped complexes for cellulose synthesis Peroxisome enzymes - structures used FA metabolism and help rid the cell of toxic intermediates Structure of flagellated sperm Formation of a phragmoplast
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Genetic Evidence Comparisons of both nuclear and chloroplast genes point to charophytes as the closest living relatives of land plants ANCESTRAL ALGA Red algae Chlorophytes Charophytes Embryophytes Plantae
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Adaptations Enabling the Move to Land In charophyceans a layer of a durable polymer called sporopollenin prevents exposed zygotes from drying out The accumulation of traits that facilitated survival on land may have opened the way to its colonization by plants The movement onto land by charophyte ancestors provided unfiltered sun, more plentiful CO 2 , nutrient-rich soil, and few herbivores or pathogens
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Defining the Plant Kingdom Systematists are currently debating the boundaries of the plant kingdom Some biologists think the plant kingdom should be expanded to include some or all green algae Until this debate is resolved, we will retain the embryophyte definition of kingdom Plantae Only the plants with embryos are the included in the Kingdom embryophyte - Another name for land plants, recognizing that land plants share the common derived trait of multicellular, dependent embryos.
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ANCESTRAL ALGA Red algae Chlorophytes Charophytes Embryophytes Viridiplantae Streptophyta Plantae
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Derived Traits of Plants Four key traits appear in nearly all land plants but are absent in the charophytes:
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This note was uploaded on 03/31/2009 for the course BISC 120Lg taught by Professor 11:00-01:50pm during the Fall '06 term at USC.

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29_Lectures_2008_Class - Chapter 29 Plant Diversity I How...

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