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CHAPTER 16 Plants, Fungi, and the Move onto Land Figures 16.1 – 16.5 PowerPoint® Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Neil Campbell, Jane Reece, and Eric Simon Presentation prepared by Chris C. Romero Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Some giant sequoia trees weigh more than a dozen space shuttles • Flowering plants such as corn, rice, and wheat provide nearly all our food. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • A mushroom is probably more closely related to humans than it is to any plant • Every 2 seconds humans destroy an area of tropical rain forest equal to the area of 3 football fields. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 1 BIOLOGY AND SOCIETY: THE BALANCING ACT OF FOREST CONSERVATION • Coniferous forests are highly productive – They provide lumber for building and wood pulp for paper. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Our demand for wood and paper is so great that clear-cut areas have become commonplace. Figure 16.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The loss of coniferous forests – Threatens the trees and other organisms that live in forests – Can be minimized by conservation practices. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 2 COLONIZING LAND • Plants – Are terrestrial organisms – Are multicellular eukaryotes that make organic molecules by photosynthesis. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Terrestrial Adaptations of Plants Structural Adaptations • Living on land poses different problems from living in water – Plants require structural specializations – Roots and shoots. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Plant Leaf performs photosynthesis Cuticle reduces water loss; stomata allow gas exchange Shoot supports plant (and may perform photosynthesis) Alga Surrounding water supports the alga Whole alga performs Photosynthesis; absorbs water, CO2 , and minerals from the water Roots anchor plant; absorb water and minerals from the soil (aided by fungi) Figure 16.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 3 • Most plants have mycorrhizae, symbiotic fungi associated with their roots. Figure 16.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Leaves – Are the main photosynthetic organs of most plants – Have stomata for gas exchange – Contain vascular tissue for transporting vital materials. Figure 16.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Other types of vascular tissue are found in the roots and shoots of plants. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 4 Reproductive Adaptations • Plants produce their gametes in protective structures called gametangia. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • In plants, but not algae, the zygote develops into an embryo while still contained within the female parent. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Ovary of flower Embryo Maternal tissue Figure 16.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 5 The Origin of Plants from Green Algae • The move onto land and the spread of plants to diverse terrestrial environments were incremental Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Molecular comparisons and other evidence place a group of green algae called charophyceans closest to plants. Figure 16.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings PLANT DIVERSITY • The history of the plant kingdom is a story of adaptation to diverse terrestrial habitats. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 6 Highlights of Plant Evolution • The fossil record chronicles four major periods of plant evolution. Angiosperms Gymnosperms (e.g., conifers) Seedless vascular plants (e.g., ferns) Bryophytes (e.g., mosses) Mesozoic Paleozoic Charophyceans (a group of green algae) Cenozoic Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Diversification of flowering plants First seed plants Early vascular plants Origin of plants Figure 16.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The first period – Was the origin of plants from their aquatic ancestors, charophyceans • The second period – Was the diversification of vascular plants Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 7 • The third period – Began with the origin of the seed • The fourth period – Was the emergence of flowering plants, or angiosperms. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Bryophytes • Mosses – Are the most familiar bryophytes. Figure 16.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Mosses display two key terrestrial adaptations – A waxy cuticle that helps prevent dehydration – The retention of developing embryos within the mother’s gametangium. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 8 • Mosses have two distinct versions of the plant – The gametophyte, which produces gametes – The sporophyte, which produces spores. Figure 16.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The life cycle of a moss exhibits an alternation of generations. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Spores n M si ito Mi to s sis Gametes (sperm and eggs) n Gametophyte n Haploid Fertilization Meiosis Diploid Spore capsule Sporophyte 2n ito M s si Zygote 2n Figure 16.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 9 Ferns • Ferns – Are seedless vascular plants. Figure 16.11 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • During the Carboniferous period, about 290–360 million years ago, ferns formed swampy forests that covered much of what is now Eurasia and North America – These forests formed what would become fossil fuels. Figure 16.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Gymnosperms • A drier, colder climate at the end of the Carboniferous period favored the evolution of gymnosperms, the first seed plants. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 10 Conifers • Conifers – Cover much of northern Eurasia and North America – Are usually evergreens, which retain their leaves throughout the year. Figure 16.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Terrestrial Adaptations of Seed Plants • Conifers and most other gymnosperms have three terrestrial adaptations – Further reduction of the gametophyte – The evolution of pollen – The advent of the seed. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The first adaptation is a greater development of the diploid sporophyte compared to the haploid gametophyte generation. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 11 Haploid (n) Gametophyte (n) Sporophyte (2n) Gametophyte (n) Sporophyte (2n) (a) Sporophyte dependent on gametophyte (e.g., mosses) Sporophyte (2n) (b) Large sporophyte and small, independent gametophyte (e.g., ferns) Diploid (2n) Gametophyte (n) (c) Reduced gametophyte dependent on sporophyte (seed plants) Figure 16.14 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • A pine tree of other conifer is actually a sporophyte with tiny gametophytes living in cones. Figure 16.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • A second adaptation of seed plants to dry land was the evolution of pollen • A pollen grain – Is actually the much-reduced male gametophyte – Fertilizes the female gametophyte. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 12 • The third terrestrial adaptation was the development of the seed • A seed consists of a plant embryo packaged along with a food supply within a protective coat. Seed coat (derived from integuments) Female gametophyte Integuments Spore case Food supply (derived from female gametophyte tissue) Spore Haploid (n) Pollen tube Egg nucleus Pollen grain (male gametophyte) Discharged sperm nucleus Embryo (new sporophyte) Diploid (2n) (a) Ovule (b) Fertilized ovule (c) Seed Figure 16.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Angiosperms • Angiosperms – Supply nearly all our food and much of our fiber for textiles • More efficient water transport and the evolution of the flower help account for the success of the angiosperms. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Flowers, Fruits, and the Angiosperm Life Cycle • The dominant stage of the angiosperms is a sporophyte with gametophytes in its flowers. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 13 Petal Stamen Carpel Stigma Anther Filament Style Ovary Ovule Sepal Figure 16.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The life cycle of an angiosperm. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 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 Embryo sac (female gametophyte) Endosperm Egg Zygote Sperm nuclei Sporophyte seedling Embryo (sporophyte) Seed Germinating seed Seed (develops from ovule) Figure 16.18 Fruit (develops from ovary) Haploid (n) Diploid (2n) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 14 • The seed being enclosed within an ovary distinguishes angiosperms from gymnosperms. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • A fruit – Is a ripened ovary – Helps protect the seed and increase seed dispersal – Is a major food source for animals. Figure 16.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Angiosperms and Agriculture • Angiosperms – Supply fiber, medications, perfumes, and decoration • Agriculture – Is a unique kind of evolutionary relationship between plants and animals. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 15 Plant Diversity as a Nonrenewable Resource • The exploding human population is extinguishing plant species at an unprecedented rate. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Humans depend on plants for thousands of products including food, building materials, and medicines. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Table 16.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 16 • Preserving plant diversity is important to many ecosystems as well as humans. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings FUNGI • Fungi are extremely important to ecosystems because they decompose and recycle organic materials. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Fungi – Are eukaryotes, and most are multicellular – Are more closely related to animals than plants. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 17 • A gallery of diverse fungi Figure 16.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Characteristics of Fungi • In this section, the structure and function of fungi are described. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fungal Nutrition • Fungi are heterotrophs – They digest their food externally and acquire the nutrients by absorption. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 18 Fungal Structure • The bodies of most fungi are constructed of structures called hyphae. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The hyphae – Form an interwoven mat called a mycelium – Are separated into cells by cross-walls made mainly of chitin. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Reproductive structure Sporeproducing structures Hyphae Mycelium Figure 16.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 19 Fungal Reproduction • Fungi reproduce by releasing spores that are produced either sexually or asexually. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The Ecological Impact of Fungi • Fungi – Have an enormous ecological impact. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fungi as Decomposers • Fungi and bacteria – Are the principal decomposers of ecosystems – Keep ecosystems stocked with nutrients necessary for plant growth. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 20 • Molds – Can destroy fruit, wood, and human-made materials. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Parasitic Fungi • Of the 100,000 known species of fungi, about 30% make their living as parasites. Figure 16.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • About 50 species of fungi are known to be parasitic in humans and other animals. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 21 Commercial Uses of Fungi • Fungi are commercially important – As food and in baking – In beer and wine production. Figure 16.23 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Some fungi produce antibiotics. Figure 16.24 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings EVOLUTION CONNECTION: MUTUAL SYMBIOSIS • Interdependence between species, or symbiosis, is an evolutionary product – Mutualism is symbiosis that benefits both species. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 22 • Lichens – Are symbiotic associations between fungi and algae. Figure 16.25 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings SUMMARY OF KEY CONCEPTS Leaves are main photosynthetic organs • Terrestrial Adaptations of Plants. Gametangia protect gametes from dehydration; female gametangia protect developing embryos Cuticle reduces water loss Stomata allow gas exchange between plant and atmosphere Lignin hardens cell walls Shoot supports plant; may perform photosynthesis Vascular tissues transport water, minerals, and sugars; provide support Roots anchor plant; mycorrhizae (root/fungus associations) help absorb water and minerals from the soil) Visual Summary 16.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Highlights of Plant Evolution. Origin of gametangia (protect gametes and embryos) Diversification of seedless vascular plants (vascular tissue conducts water and nutrients) Origin of seeds (protect embryos from desiccation and other hazards) Origin of flowers (bear ovules within protective chambers called ovaries) Visual Summary 16.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 23