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CHAPTER 28 The Life of a Flowering Plant PowerPoint® Lectures for Essential Biology, Third Edition – Neil Campbell, Jane Reece, and Eric Simon Essential Biology with Physiology, Second Edition – Neil Campbell, Jane Reece, and Eric Simon Lectures by Chris C. Romero Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Biology and Society: Plant Cloning—Feast and Famine • For the past ten thousand years, humankind has cultivated plants to ensure an adequate food supply. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Potatoes, introduced to Europe in the sixteenth century, provide a good example. – They can be cloned very easily, allowing extensive cultivation. • Cloned potatoes – Fed enormous numbers of people in Ireland in the 1800s. – Are more susceptible to environmental changes due to their lack of genetic diversity. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • In the 1840s, a funguslike organism began to infect Irish potatoes, resulting in a major famine. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.1 • In addition to their importance to humans, – Plants are vital to the well-being of the Earth’s biosphere. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Structure and Function of a Flowering Plant • Angiosperms – Have dominated the land for over 100 million years. – Account for nearly 90% of the plant kingdom. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Monocots and Dicots • Botanists have traditionally classified most angiosperms into two groups, monocots and dicots, on the basis of several structural features. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.2 • The names of the groups refer to cotyledons, or seed leaves found in the embryo. • Most angiosperms are dicots. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Plant Organs: Roots, Stems, and Leaves • A plant body consists of a root system and a shoot system, each depending on the other. How Plants Obtain Minerals from Soil Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.3 Roots • A plant’s root system – Anchors it in the soil. – Absorbs and transports minerals and water. – Stores food. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Root hairs – Are tiny projections near the root tips. – Increase the surface area of the root. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Large taproots, such as those found in carrots, turnips, sugar beets, and sweet potatoes, – Store food in the form of carbohydrates such as starch. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.4 Stems • The shoot system of a plant is made up of stems, leaves, and, in angiosperms, flowers. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • When a plant stem is growing in length, the terminal bud at the apex of the stem has developing leaves. • In many plants, the terminal bud produces hormones that cause a phenomenon called apical dominance. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • In many types of plants, removing the terminal bud stimulates growth of the axillary buds. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.5 • Stems take many forms. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.6 Leaves • The leaves – Are the primary sites of photosynthesis in most plants. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Plant leaves are highly varied in their arrangements. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.7 • Plant leaves also vary in their shapes. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.8 Plant Cells • Plant cells are unique in many ways. • Plant cells contain – Chloroplasts containing chlorophyll. – A large central vacuole. – Cell walls. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.9 • Parenchyma cells – Are the most abundant type of cell in most plants. – Perform a variety of functions, such as food storage and photosynthesis. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.10a • Collenchyma cells – Provide support for parts of the plant that are still growing. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.10b • Sclerenchyma cells – Have thick secondary cell walls that provide support to the plant. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.10c • Water-conducting cells – Convey water from the roots to the stems and leaves. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.10d • Food-conducting cells – Convey food throughout a plant. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.10e Plant Tissues and Tissue Systems • The cells of plants – Are grouped into tissues with characteristic functions. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Vascular tissue called xylem – Contains water-conducting cells. • Vascular tissue called phloem – Contains food-conducting cells. • Plant tissues – Are organized into tissue systems. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Roots, stems, and leaves are made up of three tissue systems: – The dermal tissue system, the vascular tissue system, and the ground tissue system Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.11 • The dermal tissue system – Covers and protects the leaves, stems, and roots. • The vascular tissue system – Is made up of xylem and phloem. • The ground tissue system – Makes up the bulk of a young plant. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • A cross section of a root shows what the three tissue systems look like under a microscope. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.12 • The three tissue systems in leaves Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.13 • Stomata, tiny pores that allow gas exchange, – Occur in the epidermis of leaves. • The mesophyll – Is the ground tissue system in a leaf. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Plant Growth • Most plants display indeterminate growth, continuing to grow as long as they live. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Species called annuals – Complete their life cycle in a single year or growing season. • Species called biennials – Complete their life cycle in two years. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.14a, b • Plants known as perennials – Live and reproduce for many years. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.14c Primary Growth: Lengthening • Growth in all plants – Is made possible by tissues called meristems. • A meristem – Consists of unspecialized cells that divide and generate new cells and tissues. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Apical meristems – Are found at the tips of roots and in the terminal and axillary buds of shoots. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.15 • Primary growth – Consists of cell division in the apical meristems of roots and shoots. – Produces the new cells that enable a plant to grow in length. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • A growing root – Is pushed through the soil by primary growth. – Contains a root cap that protects the actively dividing cells. Root Growth in a Radish Seed (time lapse) Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.16 Secondary Growth: Thickening • Secondary growth – Results in the thickening of stems and roots. – Involves division in two meristems, the vascular cambium and the cork cambium. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The vascular cambium – Gives rise to wood near its inner surface. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.17 part 1 Figure 28.17 part 2 Figure 28.17 part 3 • Over the years, a woody stem adds more layers, resulting in annual growth rings. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.18 • The cork cambium – Is outside the vascular cambium and produces cork, one component of bark. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Life Cycle of a Flowering Plant • Many flowering plants can reproduce both sexually and asexually. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Through asexual reproduction, a single plant can produce many offspring quickly and efficiently. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.19 The Flower • Sexual reproduction in plants produces genetically distinct offspring. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • In angiosperms, – The structure specific to sexual reproduction is the flower. Flower Blooming (time lapse) Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.20 • The flower’s reproductive organs are the stamen and the carpel. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The stamen – Consists of the filament and the anther. • In the anther – Meiosis occurs, producing pollen grains that house the cells that develop into sperm. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The carpel – Consists of the stigma, style, and ovary. • The stigma receives pollen grains. • The style leads to the ovary, which houses ovules that contain developing eggs, at the base of the stigma. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Pollination and Fertilization • The plant life cycle – Alternates between haploid and diploid generations. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The sexual life cycle of an angiosperm Time Lapse of Flowering Plant Life Cycle Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.21 • The diploid plant body – Is called the sporophyte. • The haploid plant body – Is called the gametophyte. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Fertilization – Occurs when the female and male gametes unite, producing a diploid zygote. • The life cycle is completed – When the zygote divides by mitosis and develops into a new sporophyte. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The formation of the male and female gametophytes Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.22 part 1 Figure 28.22 part 2 • The first step leading to fertilization is pollination, the delivery of pollen to the stigma of a carpel. Plant Fertilization Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.23 • Many angiosperms are dependent on animals to transfer their pollen. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • After pollination, – The pollen grain germinates on the stigma forming two sperm. • Each sperm fertilizes a cell in the ovule in a process called double fertilization: – One fertilizes the egg, and the other fertilizes a second cell in the ovule. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Seed Formation • After fertilization, – The ovule begins developing into a seed. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The zygote – Divides via mitosis into a ball of cells that becomes the embryo. • The endosperm also forms from the other fertilized cell and provides nourishment for the embryo. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The result of embryonic development is a mature seed with a tough protective seed coat. Fruit Development Seed Development Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.24 Fruit Formation • A fruit – Is a mature ovary that houses and protects seeds and aids in their dispersal. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Pea pods – Are a type of fruit. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.25 • Fruits are highly varied. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.26 Seed Germination • Germination – Usually begins when the seed takes up water. • The hydrated seed expands and bursts its seed coat. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Germination in a garden pea – Involves the formation of the root and then the shoot. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.27 Evolution Connection: The Interdependence of Angiosperms and Animals • Most angiosperms – Depend on various animals for pollination and seed dispersal. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The flowers of many angiosperms – Attract pollinators that rely entirely on the flowers’ nectar and pollen for food. Bat Pollinating Agave Plant Bee Pollinating Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 28.28 • Many animals – Have very defined relationships with various flower species. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings