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Unformatted text preview: The Evolution and Diversity of Plants Lab # 3 Kingdom Plantae Characteristics of Plants o Form Multicellular o Nutrition Photosynthetic o Habitats Primarily adapted for life on land A number have acquired characteristics for life in aquatic habitats o Size Very large Diverse More than 280,000 species Characteristics of Plants in Common w/ Green Alga (Phylum Chlorophyta) o Pigments Chlorophyll a primary pigment Cholorphyll b, the carotenoids xanthophylls accessory pigment o Major Storage Product Excess carbohydrates in the form of starch Starch is stored within the chloroplasts o Cell Wall Cellulose o Reproduction Sporic meiosis A well-defined alternation of generations All plants pass through both a multicellular haploid stage and a multicellular diploid stage to reproduce sexually A multicellular diploid phase o (Termed the sporophyte generation) o Gives rise to haploid spores through the process of meiosis These spores o Grow into a multicellular haploid phase (termed the gametophyte generation) Gametophyes o Produce gametes o (Through process of mitosis and differentiation) Fertilization o When male gamete ( sperm ) combines w/ the females gamete (egg or ovum ) o Diploid zygote is formed Diploid zygote o Grows (via mitosis) into a multicellular sporophyte organism, and the process starts all over again o Plants are believed to have evolved from green alga Prior to Evolution of Plants o 550 million years ago o Life primarily aquatic Virtually no life on land o Terrestrial Environment Advantages No competition over habitat since there were no other life forms Resources From Plants Were More Abundant: o Light is not attenuated (reduced) in air as quickly as in water o CO diffuses more rapidly through air than water o Mineral elements were abundant in the primordial mineral soil Disadvantages Acquisition and maintenance of sufficient quantities of water o Loss of water was minimized by the evolution of a cuticle (a waxy coating covering the body) that prevented the evaporation of water from the cells o Cuticle also impedes movement of gases o Since plants need CO to absorb and O to release for photosynthesis, stomata (and, in some cases, pores ) evolved at about the same time to allow gas exchange To Understand Evolution of Plants o Examine extant (living) of plants o Purposes of lab: 1. To illustrate the diversity of extant plant live 2. To illustrate some of the more important characteristics and developments that arose in the plant kingdom over evolutionary time o Important to remember: Each group did not give rise to the subsequent group Each shared a common ancestor Yet, examining them in order will allow an understanding of the developments that took place over evolutionary time Groups of Plants o Bryophytes Size Small but diverse Relation Dont appear to be closely related Common Characteristics Btw Members:...
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