ECOL 182R 1st Edition Lecture 9 Outline of Last Lecture I Protist families II Fungi A Ecological roles B Diseases C Structure Outline of Current Lecture I Plantae II Land plants A History B Gametophytes vs sporophytes III Nonvascular plants IV Vascular plants V Angiosperms Current Lecture Plantae Major group of eukaryotes includes small group of unicellular algae red algae green algae the land plants Green algae land plants green plants This group excluding the algae land plants In plant evolution innovations of each new group lead to domination by that group Land plants Photosynthetic eukaryotes that use chlorophyll a and b and store carbs as starch They all have a resting embryo The conquest of the land History of plants on land 500 mya a few algae lichens By 460 mya primitive land plants By about 300 mya great forests How does it happen Obstacles Varying temperatures the atmosphere didn t have that layer of ozone There was more UV light reaching the earth s surface Early innovations in land plant evolution Waxy cuticle that protects against drying temp fluctuations Protected embryo Association with fungi for nutrient and water uptake Might be necessary because there was initially rocky land and very little soil What causes soil Organic materials In the process of meiosis chromosome number is halved Mitosis simple cell division preserves chromosome number How to remember the diff between gametophyte sporophyte Sporophyte makes spores Gametophyte makes gametes Both are haploid Gametophyte is involved in fertilization formation of a zygote Meiosis is involved in making spores Mitosis is involved in making gametes Nonvascular Plants Protected embryos Liverworts Hornworts Mosses Small plants compared to present day shrubs trees Lack tracheids specialized water food conducting tubes of the vascular plants Collect water on leaves rely on direct absorption and diffusion of water and minerals Why are they small Stomata pores that open and close that regulate CO2 uptake Vascular plants Have tracheids thick walled dead water conducting cells More efficient water movement and support for tall plants Club Mosses Ferns have complex true leaves Ferns in particular have spores in sacs clustered on the bottom of the leaf Those missing blanks are the flowering plants Seed plants Evolution of seeds and pollen Seeds are protected resting stage that may persist in soil for years Seeds a key adaptation long lived resistant to drying heat Longest lived seed on record 2000 years Angiosperms Highly diverse 80 of plant life on earth Unique straits flowers fruits Virtually all plant material we eat comes from angiosperms Pollen tube grows down to deliver sperm to egg In general seeds don t do well under parent plant zone of death Animal pollination is better than wind pollination
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