Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Chapter 17 Plants, Fungi, and the Colonization of Land

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Plants and Fungi—A Beneficial Partnership Orange groves in Florida, Texas, and California –Rely on associations between plants and fungi

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Mycorrhizae, mutually beneficial associations of plant roots and fungi –Are common, and may have enabled plants to colonize land A mycorrhizal fungus enveloping roots of a red pine tree

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PLANT EVOLUTION AND DIVERSITY 17.1 Plants evolved from green algae Molecular, physical, and chemical evidence –Indicates that green algae called charophyceans are the closest living relatives of plants LM 444  Figure 17.1A, B

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 17.2 Plants have adaptations for life on land Plants are multicellular photosynthetic eukaryotes

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Plants have some specific adaptations –That are not found in algae Plant Roots anchor plant; absorb water and minerals from the soil Reproductive structures, as in flowers, contain spores and gametes Cuticle covering leaves and stems reduces water loss; stomata in leaves allow gas exchange Leaf performs photosynthesis Surrounding water supports alga Stem supports plant and may perform photosynthesis Whole alga performs photosynthesis; absorbs water, CO 2, and minerals from the water Holdfast anchors alga Alga Figure 17.2A

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Obtaining Resources from Two Locations Apical meristems –Are the growth-producing regions of a plant –Help maximize exposure to the resources in the soil and air

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Plants have vascular tissue –Which helps distribute nutrients throughout the organism Figure 17.2B

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Supporting the Plant Body The cell walls of some plant tissues –Are thickened and strengthened by lignin

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Maintaining Moisture A waxy cuticle covers the stems and leaves of plants –And helps retain water Stomata –Are tiny pores in leaves that allow for gas exchange

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Reproducing on Land Many living plants –Produce gametes that are encased in protective structures

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 17.3 Plant diversity reflects the evolutionary history of the plant kingdom Some highlights of plant evolution Origin of vascular plants (about 420 mya) Origin of seed plants (about 360 mya) Origin of land plants (about 475 mya) Seed plants Land plants Bryophytes (nonvascular plants) Vascular plants Seedless vascular plants Liverworts Hornworts Mosses Lycophytes (club mosses and relatives) Pterophytes (ferns and relatives) Angiosperms Gymnosperms Figure 17.3A

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Bryophytes lack vascular tissue and include –The mosses, hornworts, and liverworts Figure 17.3B

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Vascular plants –Have supportive vascular tissues

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Ferns are seedless vascular plants –With flagellated sperm Figure 17.3C

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Seed plants –Have pollen grains that transport sperm –Protect their embryos in seeds

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Gymnosperms, such as pines –Produce seeds in cones Figure 17.3D

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The seeds of angiosperms –Develop within protective ovaries Figure 17.3E

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ALTERNATION OF GENERATIONS AND PLANT LIFE CYCLES 17.4 Haploid and diploid generations alternate in plant life cycles The haploid gametophyte – Produces eggs and sperm by mitosis

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The zygote develops into the diploid sporophyte –In which meiosis produces haploid spores Spores grow into gametophytes

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Alternation of generations Sporophyte plant (2n) Key Fertilization Gametophyte plant (n) Haploid (n) Diploid (2n) Sperm Egg Mitosis Zygote (2n) Gametes (n) Spores (n) Mitosis Meiosis Figure 17.4

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 17.5 Mosses have a dominant gametophyte A mat of moss is mostly gametophytes –Which produce eggs and swimming sperm The zygote develops on the gametophyte –Into the smaller sporophyte

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Life cycle of a moss Figure 17.5 Key Haploid (n) Diploid (2n) Spores (n) Egg (n) Sperm (n) (released from gametangium) Sporophytes (growing from gametophytes) Meiosis Sporangium Female Gametophytes (n) Fertilization Stalk Sporophyte (2n) Male Zygote (2n) Mitosis and development 3 4 5

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 17.6 Ferns, like most plants, have a dominant sporophyte Sperm, produced by the gametophyte –Swim to the egg

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Life cycle of a fern Figure 17.6 Key Haploid (n) Diploid (2n) Egg (n) Zygote (2n) Sperm (n) (released from male gametangium) Gametophyte (n) (underside) Fertilization Clusters of sporangia New sporophyte (2n) growing out of gametophyte Mature sporophyte (independent of gametophyte) Spores (n) Meiosis Female gametangium (n) 1 2 Mitosis and development 3 4 5

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 17.7 Seedless plants dominated vast “coal forests” Ferns and other seedless plants –Once dominated ancient forests Their remains formed coal Figure 17.7

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 17.8 A pine tree is a sporophyte with tiny gametophytes in its cones A sperm from a pollen grain –Fertilizes an egg in the female gametophyte The zygote develops into a sporophyte embryo –And the ovule becomes a seed, with stored food and a protective coat

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Figure 17.8 Life cycle of a pine tree Key Haploid (n) Diploid (2n) Zygote (2n) Fertilization Mature sporophyte Pollen grains (male gametophytes) (n) Meiosis Female gametophyte (n) Eggs (n) Sperm (n) Male gametophyte (pollen grain) Seed coat Embryo (2n) Food supply Seed Ovule Scale Meiosis Sporangium (2n) Spore mother cell (2n) Integument Female cone bears ovules. 1 Sporangia in male cone produce spores by meiosis; spores develop into pollen grains. 2 Pollination 3 A haploid spore cell in ovule develops into female gametophyte, which makes eggs. 4 Male gametophyte (pollen) grows tube to egg and makes and releases sperm. 5 Zygote develops into embryo, and ovule becomes seed. 6 Seed germinates, and embryo grows into seedling. 7

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 17.9 The flower is the centerpiece of angiosperm reproduction Flowers usually consist of –Sepals, petals, stamens (which produce pollen), and carpels (which produce eggs) Anther Filament Stamen Petal Receptacle Ovule Sepal Stigma Style Ovary Carpel Figure 17.9A, B

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The angiosperm plant is a sporophyte with gametophytes in its flowers In the angiosperm life cycle –Ovules become seeds, and ovaries become flowers

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Life cycle of an angiosperm Sperm Figure Pollen grains (n) Meiosis Stigma Pollen grain Pollen tube Egg (n) Ovule Fertilization Embryo (2n) Food supply Seed coat Seeds Key Haploid (n) Diploid (2n) Sporophyte (2n) Ovule Ovary Stigma Anther 1 Haploid spores in anthers develop into pollen grains: male gametophytes. 2 Haploid spore in each ovule develops into female gametophyte, which produces egg. 3 Pollination and growth of pollen tube 4 Zygote (2n) 5Seed 6 Fruit (mature ovary) 7Seed germinates, and embryo grows into plant.

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The structure of a fruit reflects its function in seed dispersal Fruits are adaptations that disperse seeds Figure 17.11A–C

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION Agriculture is based almost entirely on angiosperms Angiosperms provide most of our food –And other important commercial products

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Interactions with animals have profoundly influenced angiosperm evolution Angiosperms –Are a major source of food for animals

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Animals also aid plants in pollination Figure 17.13A–C

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION Plant diversity is a nonrenewable resource Many types of forests –Are being destroyed worldwide Figure 17.14

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Some plants in these forests –Can be used in medicinal ways Table 17.14