Chapter 29 - CR

Chapter 29 - CR - 1 of 18 of 18 Chapter 29 Chapter 29 Plant...

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Unformatted text preview: 1 of 18 of 18 Chapter 29 Chapter 29 Plant Diversity I: How Plants Colonized Land 2 of 18 of 18 Overview: The Greening of Earth 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 Earths history the terrestrial surface was lifeless Since colonizing land plants have diversified into roughly 290,000 living species Figure 29.1 3 of 18 of 18 29.1: Land plants evolved from 29.1: Land plants evolved from green algae green algae Researchers have identified green algae called Charophyceans as the closest relatives of land plants Many morphological and biochemical characteristics of land plants also appear in a variety of algal clades There are four key traits that land plants share only with charophyceans 1. Rose-shaped complexes for cellulose synthesis 4 of 18 of 18 Plant charophycean traits in common, cont. 1. Peroxisome enzymes- Helps with cellular metabolism and detoxification 2. Similar structure of flagellated sperm 3. Formation of a phragmoplast- An alignment of vesicles and cytoskeletal parts along the midline of a cell Genetic Evidence Comparisons of both nuclear and chloroplast genes point to charophyceans as the closest living relatives of land plants Chara , a pond organism (a) 10 mm Coleochaete orbicularis , a disk- shaped charophycean (LM) (b) 40 m Figure 29.3a, b 5 of 18 of 18 Adaptations Enabling the Move to Adaptations Enabling the Move to Land 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 6 of 18 of 18 29.2: Land plants possess a set 29.2: Land plants possess a set of derived terrestrial adaptations of derived terrestrial adaptations Many adaptations emerged after land plants diverged from their charophycean relatives Some biologists think that the plant kingdom should be expanded to include some or all green algae This textbook retains the embryophyte definition of kingdom Plantae Systematists are currently debating the boundaries of the plant kingdom 7 of 18 of 18 Derived Traits of Plants...
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This note was uploaded on 04/07/2008 for the course BIO 103 taught by Professor Mannino during the Fall '08 term at Long Island U..

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Chapter 29 - CR - 1 of 18 of 18 Chapter 29 Chapter 29 Plant...

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