Ch 30 Material

Ch 30 Material - CHAPTER 30 PLANT DIVERSITY II: THE...

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1 CHAPTER 30 PLANT DIVERSITY II: THE EVOLUTION OF SEED PLANTS The evolution of seeds The emergence of the importance of seed plants to animals Two important landmarks in the evolution of plants The cultivation and harvest of plants (primarily seed plants), began approximately 13,000 years ago in Asia, Europe, and the Americas. 8-10 thousand year old domesticated squash seed from cave in Mexico Anatomy of a Seed Embryo Food Supply Seed coat Enhanced the ability of plants to survive and reproduce in diverse, terrestrial environments . The importance of the evolution of seed production 1. continued reduction of the gametophyte form of the life cycle 2. the advent of the seed 3. the evolution of pollen 4. Heterospory Adaptations contributing to the success of seed plants as terrestrial organisms
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Reduction of the Gametophyte Bryophytes > Seedless Vascular Plants > Seed Plants Progressively smaller gametophyte stage of life cycle Microspores (male) become pollen grains Female megaspores produce egg cells Nonvascular or Vascular Seedless Plants (HOMOSPOROUS PLANTS) Seed Plants (HETEROSPOROUS PLANTS) Sporophyte Female Gametophyte Gametophytes of Seed Plants are Tiny! Microscopic male gametophyte inside a pollen grain Microscopic female gametophyte dependent upon the sporophyte Bryophyta (nonvascular plant) Pterophyta (fern) Seedless vascular plant Seed Plants So, why hasn’t the gametophyte generation been completely
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This note was uploaded on 04/02/2008 for the course BIOL 112 taught by Professor Vaughn during the Spring '08 term at Texas A&M.

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Ch 30 Material - CHAPTER 30 PLANT DIVERSITY II: THE...

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