Plants & Life Cycles Chapter 12

Major groups of “plants” zBlue-green bacteria zAlgae zFungi zMosses zFerns and allies zGymnosperms zAngiosperms

Generalized Plant Life Cycle FERTILIZATION zygote (2N) SPOROPHYTE 2N spore mother cells MEIOSIS spore GAMETOPHYTE N diploid generation haploid generation antheridium archegonium sperm egg

Life Cycle of a Flowering Plant

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

Homosporous or Heterosporous?

Summary of spore types in free-sporing and seed plants Bryophytes: Mosses & Liverworts Homosporous Ferns and allies Homosporous & Heterosporous Seed Plants: gymnosperms & angiosperms heterosporous

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

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

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

3. What process causes the diploid stage to become haploid? A.meiosis B.mitosis C.fertilization D.sterilization E.germination

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

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

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)

4. What type of life cycle do most animals have (including humans)? A.zygotic B.gametic C.sporic

Major Evolutionary Advances Flowers 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 mya Needed on land - why? Seeds 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