Chapter 16 Plants, Fungi, and the Move onto Land

Chapter 16 Plants, Fungi, and the Move onto Land
Laura Coronado Bio Chapter 16

Biology and Society: Will the Blight End the Chestnut?
American chestnut trees Once dominated forests of the eastern United States Were prized for their Rapid growth Huge size Rot-resistant wood Around 1900, an Asian fungus was accidentally introduced from China into North America, and in just 25 years, blight caused by the fungus killed virtually all adult American chestnut trees. Fortunately, this type of harmful interaction between plant and fungus is unusual. Many plants and fungi benefit from each other’s existence. Laura Coronado Bio Chapter 16

Laura Coronado Bio 10 Chapter 16
Bacteria Archaea Protists Eukarya Plants Figure 16.UN01 Plant tree orientation diagram Fungi Animals Laura Coronado Bio Chapter 16 Figure 16.UN01

Terrestrial Adaptations of Plants Structural Adaptations
Plants are terrestrial organisms that include forms that have returned to water, such as water lilies. A plant is A multicellular eukaryote A photoautotroph, making organic molecules by photosynthesis In terrestrial habitats, the resources that a photosynthetic organism needs are found in two very different places: Light and carbon dioxide are mainly available in the air Water and mineral nutrients are found mainly in the soil Laura Coronado Bio Chapter 16

Terrestrial Adaptations of Plants Structural Adaptations
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 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 Laura Coronado Bio Chapter 16

Reproductive structures (such as those in flowers) contain spores and gametes 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 Figure 16.1 Structural adaptations of algae and plants Surrounding water supports the alga Roots anchor plant; absorb water and minerals from the soil (aided by fungi) Laura Coronado Bio Chapter 16 Figure 16.1

Roots Fungus Figure 16.2 Mycorrhizae: symbiotic associations of fungi and roots. Root surrounded by fungus Laura Coronado Bio Chapter 16 Figure 16.2

Plant Structures 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 Vascular tissue in plants is also found in the Roots Shoots Two types of vascular tissue exist in plants: Xylem transports water and minerals from roots to leaves Phloem distributes sugars from leaves to the roots and other nonphotosynthetic parts of the plant Laura Coronado Bio Chapter 16

Leaves Gametangia Stomata Cuticle Lignin Shoot Vascular tissues Figure 16.UN07 Summary: Terrestrial Adaptations of Plants Roots Laura Coronado Bio Chapter 16 Figure 16.UN07

Phloem Vascular tissue Xylem Figure 16.3 Network of vascular tissue in a leaf. Oak leaf Laura Coronado Bio Chapter 16 Figure 16.3

Reproductive Adaptations
Plants produce their gametes in protective structures called gametangia, which have a jacket of protective cells surrounding a moist chamber where gametes can develop without dehydrating. The zygote develops into an embryo while still contained within the female parent in plants but not in algae. Laura Coronado Bio Chapter 16

LM Embryo Maternal tissue Figure 16.4 The protected embryo of a plant Laura Coronado Bio Chapter 16 Figure 16.4

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 Charophytes Are a modern-day lineage of green algae May resemble one of these early plant ancestors Laura Coronado Bio Chapter 16

Figure 16.5 Two species of charophytes, the closest algal relatives of plants LM LM Laura Coronado Bio Chapter 16 Figure 16.5

PLANT DIVERSITY & EVOLUTION
The history of the plant kingdom is a story of adaptation to diverse terrestrial habitats. The fossil record chronicles four major periods 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 Laura Coronado Bio Chapter 16

Charophytes (a group of green algae) Origin of first terrestrial adaptations (about 475 mya) Ancestral green algae Nonvascular plants (bryophytes) Bryophytes Land plants Origin of vascular tissue (about 425 mya) Ferns and other seedless vascular plants Seedless vascular plants Origin of seeds (about 360 mya) Vascular plants Gymnosperms Origin of flowers (about 140 mya) Angiosperms Seed plants Figure 16.6 Highlights of plant evolution 600 500 400 300 200 100 Millions of years ago Laura Coronado Bio Chapter 16 Figure 16.6

Bryophytes Ferns Gymnosperms Figure 16.UN02 Bryophytes tree orientation diagram Angiosperms Laura Coronado Bio Chapter 16 Figure 16.UN02

PLANT EVOLUTION (2) About 425 million years ago ferns evolved With vascular tissue hardened with lignin But without seeds (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. Today, conifers, consisting mainly of cone-bearing trees such as pines, are the most diverse and widespread gymnosperms. (4) About 140 million years ago angiosperms evolved with complex reproductive structures called flowers that bear seeds within protective chambers called ovaries. Laura Coronado Bio Chapter 16

Plant Diversity The great majority of living plants Are angiosperms Include fruit and vegetable crops, grains, grasses, and most trees Are represented by more than 250,000 species Laura Coronado Bio Chapter 16

(seedless vascular plants)
PLANT DIVERSITY Bryophytes (nonvascular plants) Ferns (seedless vascular plants) Gymnosperms (naked-seed plants) Angiosperms (flowering plants) Figure 16.7 The major groups of plants Laura Coronado Bio Chapter 16 Figure 16.7

Bryophytes Bryophytes, most commonly mosses Sprawl as low mats over acres of land Need water to reproduce because their sperm swim to reach eggs within the female gametangium Have two key terrestrial adaptations: A waxy cuticle that helps prevent dehydration The retention of developing embryos within the mother plant’s gametangium Laura Coronado Bio Chapter 16

Figure 16.8 A peat moss bog in Scotland Laura Coronado Bio Chapter 16 Figure 16.8

Spores Spore capsule Sporophyte Figure 16.9 The two forms of a moss Gametophytes Laura Coronado Bio Chapter 16 Figure 16.9

Mosses Mosses have two distinct forms: The gametophyte, which produces gametes The sporophyte, which produces spores The life cycle of a moss exhibits an alternation of generations shifting between the gametophyte and sporophyte forms. Mosses and other bryophytes are unique in having the gametophyte as the larger, more obvious plant. Laura Coronado Bio Chapter 16

osis Mit osis Mit Gametes: sperm and eggs (n) Spores (n) Gametophyte (n) MEIOSIS FERTILIZATION Spore capsule Zygote (2n) Sporophyte (2n) t o Mi sis Figure Alternation of generations (Step 5) Key Haploid (n) Diploid (2n) Laura Coronado Bio Chapter 16 Figure

Ferns Ferns are Seedless vascular plants By far the most diverse with more than 12,000 known species The sperm of ferns, like those of mosses Have flagella Must swim through a film of water to fertilize eggs Laura Coronado Bio Chapter 16

Figure Ferns (seedless vascular plants) Spore capsule “Fiddlehead” (young leaves ready to unfurl) Laura Coronado Bio Chapter 16 Figure 16.11

Carboniferous Period During the Carboniferous period, from about 360 to 300 million years ago, ferns Were part of a great diversity of seedless plants Formed swampy forests over much of what is now Eurasia and North America As they died, these forests formed coal. Fossil fuels Include coal, oil, and natural gas Formed from the remains of long-dead organisms Laura Coronado Bio Chapter 16

Figure A "coal forest" of the Carboniferous period Laura Coronado Bio Chapter 16 Figure 16.12

Gymnosperms At the end of the Carboniferous period, the climate turned drier and colder, favoring the evolution of gymnosperms, which can Complete their life cycles on dry land Withstand long, harsh winters The descendants of early gymnosperms include the conifers, or cone-bearing plants. Laura Coronado Bio Chapter 16

Conifers Cover much of northern Eurasia and North America Are usually evergreens, which retain their leaves throughout the year Include the tallest, largest, and oldest organisms on Earth Figure A coniferous forest in Banff National Park, in Alberta, Canada Laura Coronado Bio Chapter 16

Terrestrial Adaptations of Seed Plants
Conifers and most other gymnosperms have three additional terrestrial adaptations: Further reduction of the gametophyte Pollen Seeds Seed plants have a greater development of the diploid sporophyte compared to the haploid gametophyte generation. A pine tree or other conifer is actually a sporophyte with tiny gametophytes living in cones. Laura Coronado Bio Chapter 16

Gametophyte (n) Sporophyte (2n) Sporophyte (2n) Sporophyte (2n) Gametophyte (n) Gametophyte (n) (a) Sporophyte dependent on gametophyte (e.g., mosses) (b) Large sporophyte and small, Independent gametophyte (e.g., ferns) (c) Reduced gametophyte dependent on sporophyte (seed plants) Figure Three variations on alternation of generations in plants. Key Haploid (n) Diploid (2n) Laura Coronado Bio Chapter 16 Figure 16.14

Scale Ovule-producing cones; the scales contain female gametophytes Pollen-producing cones; they produce male gametophytes Figure A pine tree, the sporophyte, bearing two types of cones containing gametophytes Ponderosa pine Laura Coronado Bio Chapter 16 Figure 16.15

Terrestrial Adaptations of Seed Plants
A second adaptation of seed plants to dry land was the evolution of pollen. A pollen grain Is actually the much-reduced male gametophyte Houses cells that will develop into sperm The third terrestrial adaptation was the development of the seed, consisting of A plant embryo A food supply packaged together within a protective coat Laura Coronado Bio Chapter 16

Seeds Develop from structures called ovules, located on the scales of female cones in conifers Can remain dormant for long periods before they germinate, as the embryo emerges through the seed coat as a seedling Laura Coronado Bio Chapter 16

Haploid (n) Diploid (2n) Female cone, cross section Cross section of scale Integument Spore case (a) Ovule Spore Egg nucleus Spore case Female gametophyte (b) Fertilized ovule Pollen tube Discharged sperm nucleus Figure From ovule to seed (Step 3) Pollen grain (male gametophyte) Seed coat (derived from integument) (c) Seed Food supply (derived from female gametophyte tissue) Embryo (new sporophyte) Laura Coronado Bio Chapter 16 Figure

Angiosperms 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 Their success is largely due to A more efficient water transport The evolution of the flower Laura Coronado Bio Chapter 16

Flowers, Fruits, & the Angiosperm Life Cycle
Flowers help to attract pollinators who transfer pollen from the sperm-bearing organs of one flower to the egg-bearing organs of another. A flower is actually a short stem with four whorls of modified leaves: Sepals Petals Stamens Carpels Flowers are an essential element of the angiosperm life cycle & come in many forms Laura Coronado Bio Chapter 16

Petal Stigma Anther Stamen Carpel Style Filament Ovary Figure Structure of a flower Ovule Sepal Laura Coronado Bio Chapter 16 Figure 16.17

Figure A diversity of flowers Pansy Bleeding heart California poppy Water lily Laura Coronado Bio Chapter 16 Figure 16.18

Germinated pollen grain (male gametophyte) on stigma of carpel Anther at tip of stamen Pollen tube growing down style of carpel Mature sporophyte plant with flowers Ovary (base of carpel) Ovule FERTILIZATION Endosperm Embryo sac (female gametophyte) Egg Zygote Two sperm nuclei Sporophyte seedling Figure The angiosperm life cycle (Step 6) Embryo (sporophyte) Seed Germinating seed Key Haploid (n) Diploid (2n) Seed (develops from ovule) Fruit (develops from ovary) Laura Coronado Bio Chapter 16 Figure

Seed Types Although both have seeds Angiosperms enclose the seed within an ovary Gymnosperms have naked seeds Fruit Is a ripened ovary Helps protect the seed Increases seed dispersal Is a major food source for animals Laura Coronado Bio Chapter 16

Wind dispersal Animal transportation Animal ingestion Figure Fruits and seed dispersal Laura Coronado Bio Chapter 16 Figure 16.20

Angiosperms and Agriculture
Gymnosperms supply most of our lumber and paper. Angiosperms Provide nearly all our food Supply fiber, medications, perfumes, and decoration Agriculture is a unique kind of evolutionary relationship between plants and animals. Laura Coronado Bio Chapter 16

Plant Diversity as a Nonrenewable Resource
The exploding human population is Extinguishing plant species at an unprecedented rate Destroying fifty million acres, an area the size of the state of Washington, every year! Humans depend on plants for thousands of products including Food Building materials Medicines Laura Coronado Bio Chapter 16

Figure Clear-cutting of a tropical forest in Brazil Laura Coronado Bio Chapter 16 Figure 16.21

Table 16.1 A Sampling of Medicines Derived from Plants Laura Coronado Bio Chapter 16 Table 16.1

Plant Preservation Preserving plant diversity is important to many ecosystems and humans. Scientists are now rallying to Slow the loss of plant diversity Encourage management practices that use forests as resources without damaging them Laura Coronado Bio Chapter 16

FUNGI 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 Eukaryotes Typically multicellular More closely related to animals than plants, arising from a common ancestor about 1.5 billion years ago Come in many shapes and sizes Represent more than 100,000 species Laura Coronado Bio Chapter 16

Bud Colorized SEM Budding yeast A “fairy ring” Roundworm Body of fungus Mold Colorized SEM Orange fungi Figure A gallery of diverse fungi Colorized SEM Predatory fungus Laura Coronado Bio Chapter 16 Figure 16.22

Roundworm Body of fungus Figure 16.22f A gallery of diverse fungi Predatory fungus Colorized SEM Laura Coronado Bio Chapter 16 Figure 16.22f

Characteristics of Fungi
Fungi have unique Structures Forms of nutrition is chemoheterotrophs Acquire their nutrients by absorption A fungus Digests food outside its body Secretes powerful digestive enzymes to break down the food Absorbs the simpler food compounds Laura Coronado Bio Chapter 16

Fungal Structure 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 Hyphae branch repeatedly, forming an interwoven network called a mycelium (plural, mycelia), the feeding structure of the fungus. Laura Coronado Bio Chapter 16

Reproductive structure Hyphae Spore-producing structures Figure The fungal mycelium Mycelium Mycelium Laura Coronado Bio Chapter 16 Figure 16.23

Fungal Reproduction Mushrooms Arise from an underground mycelium Mainly function in reproduction Fungi reproduce by releasing billions and trillions of spores that are produced either sexually or asexually. Laura Coronado Bio Chapter 16

The Ecological Impact of Fungi
Fungi have An enormous ecological impact Many interactions with humans Fungi and bacteria Are the principal decomposers of ecosystems Keep ecosystems stocked with the inorganic nutrients necessary for plant growth Without decomposers, carbon, nitrogen, and other elements would accumulate in nonliving organic matter. Molds can destroy: Fruit, Grains, Wood, Human-made material Laura Coronado Bio Chapter 16

Parasitic Fungi Parasitic fungi absorb nutrients from the cells or body fluids of living hosts. Of the 100,000 known species of fungi, about 30% make their living as parasites, including Dutch elm disease Deadly ergot, which infests grain About 50 species of fungi are known to be parasitic in humans and other animals, causing Lung and vaginal yeast infections Athlete’s foot Laura Coronado Bio Chapter 16

Parasitic Fungi Figure 16.24a Dutch elm trees Figure 16.24b Rye seed heads with ergots (a) American elm trees killed by Dutch elm disease fungus (b) Ergots Laura Coronado Bio Chapter 16 Figure 16.24a

The Process of Science: Did a Fungus Lead to the Salem Witch Hunt?
Observation: In 1692, eight young girls were accused of being witches and had symptoms consistent with ergot poisoning. Question: Did an ergot outbreak cause the witch hunt? Hypothesis: The girls’ symptoms were the result of ergot poisoning. Prediction: The historical facts would be consistent with this hypothesis. Laura Coronado Bio Chapter 16

Figure Ergot and the Salem witch hunt Laura Coronado Bio Chapter 16 Figure 16.25

The Process of Science: Did a Fungus Lead to the Salem Witch Hunt?
Results: Agricultural records from 1691, before the symptoms appeared, indicated a particularly warm and wet year, in which ergot thrives. Records from the following year, when accusations of witchcraft died down, indicate a dry year consistent with an ergot die-off. This correlation is consistent with the hypothesis but not conclusive. Laura Coronado Bio Chapter 16

Commercial Uses of Fungi
Fungi are commercially important. Humans eat them and use them to Produce medicines such as penicillin Decompose wastes Produce bread, beer, wine, and cheeses Laura Coronado Bio Chapter 16

Truffles (the fungal kind, not the chocolates) Blue cheese Figure Fungi eaten by humans Chanterelle mushrooms Laura Coronado Bio Chapter 16 Figure 16.26

Penicillium Zone of inhibited growth Staphylococcus Figure Fungal production of an antibiotic Laura Coronado Bio Chapter 16 Figure 16.27

Evolution Connection: Mutually Beneficial Symbiosis
Symbiosis is the term used to describe ecological relationships between organisms of different species that are in direct contact. Mutually beneficial symbiotic relationships benefit both species. Examples of mutually beneficial symbiotic relationships involving fungi include Mycorrhizae, the association of fungi and plant roots Lichens, the association of fungi and algae Laura Coronado Bio Chapter 16

Algal cell Colorized SEM Figure Lichens: symbiotic associations of fungi and algae Fungal hyphae Laura Coronado Bio Chapter 16 Figure 16.28

Chapter 16 Plants, Fungi, and the Move onto Land

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Chapter 16 Plants, Fungi, and the Move onto Land

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