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

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

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

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

LM –Charophytes Are a modern-day lineage of green algae May resemble one of these early plant ancestors The Origin of Plants from Green Algae

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 Plants

Reproductive structures (such as those in flowers) contain spores and gametes Leaf performs photosynthesis Cuticle reduces water loss; stomata regulate gas exchange Shoot supports plant (and may perform photosynthesis) Surrounding water supports the alga Roots anchor plant; absorb water and minerals from the soil (aided by fungi) Whole alga performs photosynthesis; absorbs water, CO 2, and minerals from the water Alga Plant 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 Plants: Structural Adaptations Roots Fungus Root surrounded by fungus

–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 Plants: Structural Adaptations Oak leaf Phloem Xylem Vascular tissue

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

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

Bryophytes Ferns Gymnosperms Angiosperms (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

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

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

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

Highlights of Plant Evolution Petal Carpel Stamen Sepal Ovule Anther Filament Stigma Style Ovary 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

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 Eukarya Protists Plants Fungi Animals

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

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