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1. Announcements ● Tutoring Center SCI I, 407 M 12-3, 5:30-6:30; W 8-9, 5:30-6:30, Th 8-12, 6-7; F 8-9 ● MasteringBiology Assignment due Thursday 6/2 ● Today’s Lecture: Chapter 16 ● Canned food drive – donation worth 5 extra credit points

2. Prokaryotes Bacteria Prokaryotes Archaea Protists Eukarya Plants Fungi Animals Are smaller than eukaryotic cells Lack internal structures surrounded by membranes Lack a nucleus Have a rigid cell wall

3. Protists • Are eukaryotic • Evolved from prokaryotic ancestors • Are ancestral to all other eukaryotes, which are • Plants • Fungi • Animals Bacteria Prokaryotes Archaea Protists Plants Eukarya Fungi Animals

4. Plants • A plant is: • A multicellular eukaryote • A photoautotroph, making organic molecules by photosynthesis Bacteria Archaea Protists Eukarya Plants Fungi Animals

5. The Origin of Plants from Green Algae • Plants are terrestrial organisms that include forms that have returned to water, such as water lilies. • The algal ancestors of plants • Carpeted moist fringes of lakes or coastal salt marshes • First evolved over 500 million years ago

6. The Origin of Plants from Green Algae • Charophytes • Are amodern-day lineage of green algae • May resemble one of these early plant ancestors LM LM

7. Plants • The complex bodies of plants are specialized to take advantage of these two environments by having: • Aerial leaf-bearing organs called shoots • Subterranean organs called roots

8. Plants Reproductive structures (such as those in flowers) contain spores and gametes Structural Adaptations Plant Leaf performs photosynthesis Cuticle reduces water loss; stomata regulate gas exchange Shoot supports plant (and may perform photosynthesis) Alga Whole alga performs photosynthesis; absorbs water, CO2, and minerals from the water Surrounding water supports the alga Roots anchor plant; absorb water and minerals from the soil (aided by fungi)

9. Plants: Structural Adaptations • Most plants have mycorrhizae, symbiotic fungi associated with their roots, in which the fungi: • Absorb water and essential minerals from the soil • Provide these materials to the plant • Are nourished by sugars produced by the plant Roots Fungus Root surrounded by fungus

10. Plants: Structural Adaptations Phloem Vascular tissue Xylem • Leaves are the main photosynthetic organs of most plants, with • Stomata for the exchange of carbon dioxide and oxygen with the atmosphere • Vascular tissue for transporting vital materials • A waxy cuticle surface that helps the plant retain water Oak leaf

11. Plants: Reproductive Adaptations • The zygote develops into an embryo while still contained within the female parent in plants but not in algae. • The zygote develops into an embryo while still contained within the female parent in plants but not in algae. • The zygote develops into an embryo while still contained within the female parent in plants but not in algae. LM Embryo Maternal tissue

12. Highlights of Plant Evolution • The fossil record chronicles four major periods of plant evolution. Charophytes (a group of green algae) Origin of first terrestrial adaptations (about 475 mya) Ancestral green algae Bryophytes Origin of vascular tissue (about 425 mya) Ferns and Other seedless Vascular plants Origin of seeds (about 360 mya) Gymnosperms Origin of flowers (about 140 mya) Angiosperms 600 500 400 300 200 100 0 Millions of years ago

13. Highlights of Plant Evolution (1) About 475 million years ago plants originated from an algal ancestor giving rise to bryophytes, nonvascular plants, including mosses, liverworts, and hornworts that are nonvascular plants without: • Lignified walls • True roots • True leaves Bryophytes Ferns Gymnosperms Angiosperms

14. Highlights of Plant Evolution • (2) About 425 million years ago ferns evolved • With vascular tissue hardened with lignin • But without seeds Bryophytes Ferns Gymnosperms Angiosperms

15. Highlights of Plant Evolution • (3) About 360 million years ago gymnosperms evolved with seeds that consisted of an embryo packaged along with a store of food within a protective covering but not enclosed in any specialized chambers. Bryophytes Ferns Gymnosperms Angiosperms

16. Highlights of Plant Evolution • (4) About 140 million years ago angiosperms evolved with complex reproductive structures called flowers that bear seeds within protective chambers called ovaries. Bryophytes Ferns Gymnosperms Angiosperms

17. Highlights of Plant Evolution Highlights of Plant Evolution • Angiosperms • Dominate the modern landscape • Are represented by about 250,000 species • Supply nearly all of our food and much of our fiber for textiles Petal Stigma Anther Stamen Carpel Style Filament Ovary Sepal Ovule

18. Fungi • Recycle vital chemical elements back to the environment in forms other organisms can assimilate • Form mycorrhizae, fungus-root associations that help plants absorb from the soil • Minerals • Water Bacteria Archaea Protists Eukarya Plants Fungi Animals

19. Fungi • Come in many shapes and sizes • Represent more than 100,000 species Bud Colorized SEM Budding yeast A “fairy ring” Roundworm Body of fungus Mold Colorized SEM Orange fungi Colorized SEM Predatory fungus

20. Fungal Structure Reproductive structure Hyphae Spore-producing structures Mycelium • The bodies of most fungi are constructed of threadlike filaments called hyphae. • Hyphae are minute threads of cytoplasm surrounded by a: • Plasma membrane • Cell wall mainly composed of chitin