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Plants & Life Cycles Chapter 12 Slide 2 Major groups of plants zBlue-green bacteria zAlgae zFungi zMosses zFerns and allies zGymnosperms zAngiosperms Slide 3 Generalized Plant Life Cycle FERTILIZATION zygote (2N) SPOROPHYTE 2N spore mother cells MEIOSIS spore GAMETOPHYTE N diploid generation haploid generation antheridium archegonium sperm egg Slide 4 Slide 5 Slide 6 Slide 7 Slide 8 Slide 9 Slide 10 Slide 11 Life Cycle of a Flowering Plant Slide 12 Homospory and Heterospory Homospory All spore are the same, with regard to size and gender Each is capable of make a hermaphroditic, male or female gametophyte Heterospory The spore are different in size and gender Microspore = small, male Megaspore = large, female Each spore makes a specific gendered gametophyte Slide 13 Homosporous or Heterosporous? Slide 14 Slide 15 Slide 16 Slide 17 Slide 18 Slide 19 Slide 20 Summary of spore types in free-sporing and seed plants Bryophytes: Mosses & Liverworts Homosporous Ferns and allies Homosporous & Heterosporous Seed Plants: gymnosperms & angiosperms heterosporous Slide 21 Generalized Plant Life Cycle FERTILIZATION zygote (2N) SPOROPHYTE 2N Specialized diploid reproductive cells (spore mother cells) MEIOSIS spores GAMETOPHYTE (male or female) N Gametes (egg & sperm) cell division & growth cell division & growth diploid generation haploid generation Slide 22 1. What do the terms haploid and diploid refer to? A.Cell number B.Eye number C.Number of chromosomes D.Number of chromosome sets E.Number of nuclei Slide 23 2. A life cycle illustrates the reproductive stages for an organism. What process causes the haploid stage to become diploid? A.meiosis B.mitosis C.fertilization D.sterilization E.germination Slide 24 3. What process causes the diploid stage to become haploid? A.meiosis B.mitosis C.fertilization D.sterilization E.germination Slide 25 1. Zygotic Life Cycle FERTILIZATION zygote (2N) MEIOSIS Gametophyte (plant may act as gametes) Zygote is the only diploid portion of the sporophyte generation Presumably the original life cycle Slide 26 2. Gametic Life Cycle FERTILIZATION zygote (2N) SPOROPHYTE 2N Specialized diploid reproductive cells MEIOSIS Gametes (egg or sperm) cell division & growth Gametes are the only haploid portion of the gametophyte Zygote grows mitotically Slide 27 3. Sporic Life Cycle FERTILIZATION zygote (2N) SPOROPHYTE 2N Specialized diploid reproductive cells (spore mother cells) MEIOSIS spores GAMETOPHYTE (male or female) N Gametes (egg or sperm) cell division & growth cell division & growth Both generations (N and 2N) mitotic divisions Alternation of generations (sporophyte & gametophyte) Slide 28 4. What type of life cycle do most animals have (including humans)? A.zygotic B.gametic C.sporic Slide 29 Major Evolutionary Advances Flowers - 140 mya 5,000 mya 4,000 mya 3,000 mya 2,000 mya 1,000 mya Earth Forms Prokaryotic Cells Eukaryotic Cells Multicellular Plants Vascular tissue Seeds Flowers Life - 3,800 mya Prokaryotic cell/autotrophic Eukaryotic cell - 1,400 mya Multicellar plants - 1,000 mya Vascular tissue - 430 mya Needed on land - why? Seeds - 350 mya Place on the time scale, the following events: 1. Earth formation 2. Prokaryotes 3. Eukaryotes 4. Multicellular life 5. Vascular tissue 6. Seeds 7. Flowers