Lec17_PLants_handout

Lec17_PLants_handout - BioG1780 Evolution and Biodiversity...

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BioG1780 Fall 2010 Evolution and Biodiversity Today’s lecturer: Harry Greene Lectures 16: October 6, 2010 1. Seed plants. In today’s lecture we finish our coverage of the Plantae, first briefly recapping where we’ve already been in the plant TOL, then spending a bit more time on alternation of generations, and proceeding on to a survey of seed plants—the gymnosperms and angiosperms—as well as their biology and significance for humans. 2. What is alternation of generations? Throughout the five basal eukaryotic lineages and especially within the adaptive radiation in plants, we encounter a trend toward increasingly complex life cycles. “Green algae” exhibit a simple cycle in which a diploid (two sets of chromosomes) sporophyte generation through meiosis produces haploid (one set of chromosomes) spores; spores then through mitosis produce a gametophyte stage that makes gametes, gametes fuse to form a diploid zygote, and through mitosis that zygote forms a sporophyte. Unlike “green algae,” in which sporophyte and
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This note was uploaded on 12/20/2011 for the course BIOG 1440 taught by Professor Owens during the Spring '10 term at Cornell.

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