BIO 102

What will we study in BIO 102?

Single Cell Life v. Multicellular Life

OVERVIEW OF EVOLUTION… OVERVIEW OF EVOLUTION…..How did life begin and get to the multicellular stage? https://www.youtube.com/watch?v=H2_6cqa2cP4

Table 15.6-2 The geologic record (part 2)

Table 15.6-1 The geologic record (part 1)

Key events in life’s history 4.6 bya 3.5 bya 1.8 bya 1 bya 500 mya

Evolution of Plants and Fungal Diversity Chapter 17 Evolution of Plants and Fungal Diversity

What were the challenges to plants as they moved onto land? Think about… What were the challenges to plants as they moved onto land?

Introduction Mutually beneficial symbioses between plants and fungi began 500 million years ago, when plants first occupied land. These intimate associations allow plants to tap a vast underground network of fungal filaments into which water and mineral nutrients flow. Plants supply mycorrhizae with sugars and other organic molecules. At least 90% of all plants form such relationships.

17.1 Plants have adaptations for life on land More than 500 million years ago, the algal ancestors of plants may have carpeted moist fringes of lakes and coastal salt marshes. Plants, and green algae called charophytes are thought to have evolved from a common ancestor, have complex multicellular bodies, and are photosynthetic eukaryotes. Student Misconceptions and Concerns Students often mistakenly conceive of evolution as a deliberate and directed process, in which organisms somehow acquire adaptations out of want or need. This chapter provides good examples of how evolution actually occurs. During the period when plants first moved onto land, the demands of a terrestrial environment selected among the diversity already existing within the various marginal plant species. For example, plants that produced structures that provided some physical support outside of water had an advantage over those without such structures. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations in existing aquatic plants conveyed advantages in this new environment and were therefore favored. (17.1–17.2) The text notes that the modern day alga Coleochaete may resemble one of the early plant ancestors. Students might misinterpret this to mean that this alga may be a direct ancestor of plants. Instead, the alga Coleochaete and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Although such distinctions may be clear to us as instructors, beginning students with little experience can easily be confused. (17.1–17.2) Teaching Tips Point out to your students that in an aquatic environment, resources such as nutrients and water are accessible to the entire plant. However, structural adaptations such as roots and shoots have evolved in plants that live on land, where such resources are less accessible. (17.1) Consider an analogy between vascular systems in plants and a major interstate highway, with traffic running in opposite directions. Highways, like vascular tissues, permit the widespread distribution of concentrated resources. (17.1) Have your students discuss the specific advantages of similar adaptations in the reproductive systems of plants and viviparous mammals. What are the advantages of housing a developing embryo with the parent? (One example: The embryonic environment can be carefully regulated by the parent, and the parent can better protect the young from damage, disease, or predation.) (17.1) Active Lecture Tips Before addressing plant evolution, have your students work in small groups to list the demands of living on land versus in water. Ask them to consider the challenges that plants faced when they moved onto land. Adaptations that addressed these challenges are discussed in Chapter 17. In part, we all are made curious by such exercises to learn what we figured out on our own! (17.1–17.2)

17.1 Plants have adaptations for life on land Life on land offered many opportunities for plant adaptations that took advantage of bright and abundant sunlight, abundant atmospheric CO2, and initially, few pathogens or plant-eating animals. Student Misconceptions and Concerns Students often mistakenly conceive of evolution as a deliberate and directed process, in which organisms somehow acquire adaptations out of want or need. This chapter provides good examples of how evolution actually occurs. During the period when plants first moved onto land, the demands of a terrestrial environment selected among the diversity already existing within the various marginal plant species. For example, plants that produced structures that provided some physical support outside of water had an advantage over those without such structures. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations in existing aquatic plants conveyed advantages in this new environment and were therefore favored. (17.1–17.2) The text notes that the modern day alga Coleochaete may resemble one of the early plant ancestors. Students might misinterpret this to mean that this alga may be a direct ancestor of plants. Instead, the alga Coleochaete and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Although such distinctions may be clear to us as instructors, beginning students with little experience can easily be confused. (17.1–17.2) Teaching Tips Point out to your students that in an aquatic environment, resources such as nutrients and water are accessible to the entire plant. However, structural adaptations such as roots and shoots have evolved in plants, that live on land, where such resources are less accessible. (17.1) Consider an analogy between vascular systems in plants and a major interstate highway, with traffic running in opposite directions. Highways, like vascular tissues, permit the widespread distribution of concentrated resources. (17.1) Have your students discuss the specific advantages of similar adaptations in the reproductive systems of plants and viviparous mammals. What are the advantages of housing a developing embryo with the parent? (One example: The embryonic environment can be carefully regulated by the parent, and the parent can better protect the young from damage, disease, or predation.) (17.1) Active Lecture Tips Before addressing plant evolution, have your students work in small groups to list the demands of living on land versus in water. Ask them to consider the challenges that plants faced when they moved onto land. Adaptations that addressed these challenges are discussed in Chapter 17. In part, we all are made curious by such exercises to learn what we figured out on our own! (17.1–17.2)

17.1 Plants have adaptations for life on land But life on land had disadvantages, too. On land, plants must 1. 2. 3. 4. 5. Some species accumulated adaptations that made life on dry land possible. Student Misconceptions and Concerns Students often mistakenly conceive of evolution as a deliberate and directed process, in which organisms somehow acquire adaptations out of want or need. This chapter provides good examples of how evolution actually occurs. During the period when plants first moved onto land, the demands of a terrestrial environment selected among the diversity already existing within the various marginal plant species. For example, plants that produced structures that provided some physical support outside of water had an advantage over those without such structures. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations in existing aquatic plants conveyed advantages in this new environment and were therefore favored. (17.1–17.2) The text notes that the modern day alga Coleochaete may resemble one of the early plant ancestors. Students might misinterpret this to mean that this alga may be a direct ancestor of plants. Instead, the alga Coleochaete and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Although such distinctions may be clear to us as instructors, beginning students with little experience can easily be confused. (17.1–17.2) Teaching Tips Point out to your students that in an aquatic environment, resources such as nutrients and water are accessible to the entire plant. However, structural adaptations such as roots and shoots have evolved in plants that live on land, where such resources are less accessible. (17.1) Consider an analogy between vascular systems in plants and a major interstate highway, with traffic running in opposite directions. Highways, like vascular tissues, permit the widespread distribution of concentrated resources. (17.1) Have your students discuss the specific advantages of similar adaptations in the reproductive systems of plants and viviparous mammals. What are the advantages of housing a developing embryo with the parent? (One example: The embryonic environment can be carefully regulated by the parent, and the parent can better protect the young from damage, disease, or predation.) (17.1) Active Lecture Tips Before addressing plant evolution, have your students work in small groups to list the demands of living on land versus in water. Ask them to consider the challenges that plants faced when they moved onto land. Adaptations that addressed these challenges are discussed in Chapter 17. In part, we all are made curious by such exercises to learn what we figured out on our own! (17.1–17.2)

Leaves carry out photosynthesis Reproductive structures, as in flowers, contain spores and gametes Cuticle covering leaves and stems reduces water loss Stomata in leaves allow gas exchange between plant and atmosphere Lignin hardens cell walls of some plant tissues Stem supports plant; may perform photosynthesis Vascular tissues in shoots and roots transport water, minerals, and sugars; provide support Figure 17.UN01 Reviewing the concepts, 17.1 Roots anchor plant; mycorrhizae (root- fungus associations) help absorb water and minerals from the soil

17.2 Plant diversity reflects the evolutionary history of the plant kingdom Three key events occurred in the history of the plant kingdom. Origin of land plants Origin of vascular plants Origin of seed plants Student Misconceptions and Concerns Students often mistakenly conceive of evolution as a deliberate and directed process, in which organisms somehow acquire adaptations out of want or need. This chapter provides good examples of how evolution actually occurs. During the period when plants first moved onto land, the demands of a terrestrial environment selected among the diversity already existing within the various marginal plant species. For example, plants that produced structures that provided some physical support outside of water had an advantage over those without such structures. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations in existing aquatic plants conveyed advantages in this new environment and were therefore favored. (17.1–17.2) The text notes that the modern day alga Coleochaete may resemble one of the early plant ancestors. Students might misinterpret this to mean that this alga may be a direct ancestor of plants. Instead, the alga Coleochaete and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Although such distinctions may be clear to us as instructors, beginning students with little experience can easily be confused. (17.1–17.2) Teaching Tips Consider an analogy between a chicken egg and the first seeds to evolve. Although the parallels are limited, each consists of a developing embryo enclosed in a water-resistant packet, along with a store of food. (17.2) The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. Each fiber of carpet and each individual moss plant might easily collapse without the support of its neighbor. (17.2) Active Lecture Tips Before addressing plant evolution, have your students work in small groups to list the demands of living on land versus in water. Ask them to consider the challenges that plants faced when they moved onto land. Adaptations that addressed these challenges are discussed in Chapter 17. In part, we all are made curious by such exercises to learn what we figured out on our own! (17.1–17.2)

Origin of vascular plants (about 425 mya) (bryophytes) plants Nonvascular Land plants Liverworts Origin of land plants (about 470 mya) Ancestral green alga 1 Mosses Hornworts Lycophytes (club mosses, spike mosses, quillworts) plants vascular Seedless Vascular plants Origin of vascular plants (about 425 mya) 2 Monilophytes (ferns, horsetails, whisk ferns) Figure 17.2a Some highlights of plant evolution Gymnosperms Origin of seed plants (about 360 mya) plants Seed 3 Angiosperms 500 450 400 350 300 Millions of years ago (mya)

17.2 Plant diversity reflects the evolutionary history of the plant kingdom Nonvascular plants (bryophytes) include the mosses, hornworts, and liverworts. Student Misconceptions and Concerns Students often mistakenly conceive of evolution as a deliberate and directed process, in which organisms somehow acquire adaptations out of want or need. This chapter provides good examples of how evolution actually occurs. During the period when plants first moved onto land, the demands of a terrestrial environment selected among the diversity already existing within the various marginal plant species. For example, plants that produced structures that provided some physical support outside of water had an advantage over those without such structures. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations in existing aquatic plants conveyed advantages in this new environment and were therefore favored. (17.1–17.2) The text notes that the modern day alga Coleochaete may resemble one of the early plant ancestors. Students might misinterpret this to mean that this alga may be a direct ancestor of plants. Instead, the alga Coleochaete and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Although such distinctions may be clear to us as instructors, beginning students with little experience can easily be confused. (17.1–17.2) Teaching Tips Consider an analogy between a chicken egg and the first seeds to evolve. Although the parallels are limited, each consists of a developing embryo enclosed in a water-resistant packet, along with a store of food. (17.2) The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. Each fiber of carpet and each individual moss plant might easily collapse without the support of its neighbor. (17.2) Active Lecture Tips Before addressing plant evolution, have your students work in small groups to list the demands of living on land versus in water. Ask them to consider the challenges that plants faced when they moved onto land. Adaptations that addressed these challenges are discussed in Chapter 17. In part, we all are made curious by such exercises to learn what we figured out on our own! (17.1–17.2)

17.2 Plant diversity reflects the evolutionary history of the plant kingdom Vascular plants have lignin-hardened vascular tissues that provide strong support. Ferns are seedless vascular plants. with flagellated sperm. Student Misconceptions and Concerns Students often mistakenly conceive of evolution as a deliberate and directed process, in which organisms somehow acquire adaptations out of want or need. This chapter provides good examples of how evolution actually occurs. During the period when plants first moved onto land, the demands of a terrestrial environment selected among the diversity already existing within the various marginal plant species. For example, plants that produced structures that provided some physical support outside of water had an advantage over those without such structures. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations in existing aquatic plants conveyed advantages in this new environment and were therefore favored. (17.1–17.2) The text notes that the modern day alga Coleochaete may resemble one of the early plant ancestors. Students might misinterpret this to mean that this alga may be a direct ancestor of plants. Instead, the alga Coleochaete and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Although such distinctions may be clear to us as instructors, beginning students with little experience can easily be confused. (17.1–17.2) Teaching Tips Consider an analogy between a chicken egg and the first seeds to evolve. Although the parallels are limited, each consists of a developing embryo enclosed in a water-resistant packet, along with a store of food. (17.2) The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. Each fiber of carpet and each individual moss plant might easily collapse without the support of its neighbor. (17.2) Active Lecture Tips Before addressing plant evolution, have your students work in small groups to list the demands of living on land versus in water. Ask them to consider the challenges that plants faced when they moved onto land. Adaptations that addressed these challenges are discussed in Chapter 17. In part, we all are made curious by such exercises to learn what we figured out on our own! (17.1–17.2)

3 Challenges Vascular tissue Spores 1.Support 2.Reproduction 3. Water Leaf Spores Flagellated sperm Alga Surrounding water supports alga. Whole alga performs photo- synthesis; absorbs water, CO2, and minerals from the water. Flagellated sperm Leaf Stem Stem Roots Fern Roots Stomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue; fertilization requires moisture Figure 17.1c_1 Comparing the aquatic adaptations of Chara, a multicellular green alga, with the terrestrial adaptations of moss, fern, and pine (part 1) Moss Flagellated sperm Stomata only on sporophytes; primitive roots anchor plants; no lignin; no vascular tissue; fertilization requires moisture Holdfast (anchors alga)

17.2 Plant diversity reflects the evolutionary history of the plant kingdom Seed plants have sperm-transporting pollen grains and protect embryos in seeds. Gymnosperms, such as pines, produce seeds in cones. The seeds of angiosperms develop within protective ovaries. Student Misconceptions and Concerns Students often mistakenly conceive of evolution as a deliberate and directed process, in which organisms somehow acquire adaptations out of want or need. This chapter provides good examples of how evolution actually occurs. During the period when plants first moved onto land, the demands of a terrestrial environment selected among the diversity already existing within the various marginal plant species. For example, plants that produced structures that provided some physical support outside of water had an advantage over those without such structures. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations in existing aquatic plants conveyed advantages in this new environment and were therefore favored. (17.1–17.2) The text notes that the modern day alga Coleochaete may resemble one of the early plant ancestors. Students might misinterpret this to mean that this alga may be a direct ancestor of plants. Instead, the alga Coleochaete and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Although such distinctions may be clear to us as instructors, beginning students with little experience can easily be confused. (17.1–17.2) Teaching Tips Consider an analogy between a chicken egg and the first seeds to evolve. Although the parallels are limited, each consists of a developing embryo enclosed in a water-resistant packet, along with a store of food. (17.2) The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. Each fiber of carpet and each individual moss plant might easily collapse without the support of its neighbor. (17.2) Active Lecture Tips Before addressing plant evolution, have your students work in small groups to list the demands of living on land versus in water. Ask them to consider the challenges that plants faced when they moved onto land. Adaptations that addressed these challenges are discussed in Chapter 17. In part, we all are made curious by such exercises to learn what we figured out on our own! (17.1–17.2)

Pine tree Pollen Seed Leaf Stem Roots Stomata; Figure 17.1c_2 Comparing the aquatic adaptations of Chara, a multicellular green alga, with the terrestrial adaptations of moss, fern, and pine (part 2) Roots Pine tree Stomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue; fertilization does not require moisture

17.3 Haploid and diploid generations alternate in plant life cycles Plants have an alternation of generations in which the haploid and diploid stages are distinct, multicellular bodies. The haploid generation of a plant produces gametes and is called the ____________________. The diploid generation produces spores and is called the ________________. Student Misconceptions and Concerns Students can easily confuse animal and plant reproductive cycles. The unique features of alternation of generations in plants can make analogies and parallels challenging and potentially confusing when referencing animal life cycles. One possible relevant exercise would be to compare the timing of mitosis and meiosis in plant and animal life cycles. (17.3–17.4) Teaching Tips The authors describe key adaptations of life on land in Module 17.1. Modules 17.2–17.8 describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). (17.3–17.8) Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid stage does not include multicellular individuals. (17.3–17.4) Active Lecture Tips See the Activity “Concept Mapping the Alternation of Generations in Angiosperms” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (17.3–17.11)

Alternation of Generations THE PLANT LIFE CYCLE Haploid (n) Diploid (2n) Alternation of Generations Gametophyte plant (n) Sperm (n) Spores (n) Egg (n) Meiosis Fertilization Zygote (2n) Figure 17.3_1_5 The plant life cycle (step 5) Sporophyte plant (2n)

A Moss Life Cycle A Moss Life Cycle Haploid (n) Diploid (2n) Mitosis Male gametangium Sperm Spores (n) Egg Female gametangium Gametophyte plants (n) Sporangium Sporophyte Fertilization Figure 17.3_2_5 The moss life cycle (step 5) Zygote Meiosis Gametophyte

A Fern Life Cycle Gametophyte plant (n) Male gametangium Spores Sperm Cluster of sporangia Female gametangium Egg Mature sporophyte Meiosis Fertilization Zygote Figure 17.3_6_5 Fern life cycle (step 5) Haploid (n) Diploid (2n)

Anther Pollen grains (n) (male gametophytes) 1 Meiosis 3 Stigma Egg within a female gametophyte (n) Pollen grain 2 Pollen tube Meiosis Ovary Sporo- phyte (2n) Ovule Ovule containing female sporangium (2n) Sperm Germination 7 Figure 17.7_5 Life cycle of an angiosperm (step 5) Seeds 6 Food supply Fertilization Seed coat Fruit (mature ovary) 4 Zygote (2n) Haploid (n) 5 Embryo (2n) Diploid (2n) Seed

17.5 Pollen and seeds are key adaptations for life on land Gymnosperms have pollen grains that carry their sperm-producing cells through the air. Angiosperms use the air or other organisms for pollen dispersal. If a pollen grain lands on a compatible female structure, an event known as pollination, it undergoes mitosis to produce a sperm. In seed plants, the sperm is reduced to a nucleus. The zygote develops into a sporophyte embryo, and the ovule becomes a seed, with stored food and a protective seed coat. Teaching Tips The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, which is commonly provided as part of weather reports. It might be interesting to track the pollen counts as you go through the semester. (17.4–17.5) As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. As the text notes, gymnosperm cones are modified shoots and angiosperm flowers represent the remodeling of leaves. These examples of remodeling might be a subject to explore in additional detail as an important lesson in evolution. (17.5–17.6) The authors describe key adaptations of life on land in Module 17.1. Modules 17.2–17.8 describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). (17.3–17.8) Active Lecture Tips See the Activity “Concept Mapping the Alternation of Generations in Angiosperms” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (17.3–17.11)

Longitudinal section of ovulate cone Sporangia Longitudinal section Figure 17.5a Male and female pine cones Longitudinal section of pollen cone

Animation: Pine Life Cycle © 2018 Pearson Education, Inc.

How do pollen and seeds increase the reproductive success of seed plants? Checkpoint Question Response Pollen transfers sperm to eggs without the need for water. Seeds protect, nourish, and help disperse plant embryos. Teaching Tips The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, which is commonly provided as part of weather reports. It might be interesting to track the pollen counts as you go through the semester. (17.4–17.5) As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. As the text notes, gymnosperm cones are modified shoots and angiosperm flowers represent the remodeling of leaves. These examples of remodeling might be a subject to explore in additional detail as an important lesson in evolution. (17.5–17.6) The authors describe key adaptations of life on land in Module 17.1. Modules 17.2–17.8 describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). (17.3–17.8) Active Lecture Tips See the Activity “Concept Mapping the Alternation of Generations in Angiosperms” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (17.3–17.11)

17.6 The flower is the centerpiece of angiosperm reproduction Flowers usually consist of sepals, which enclose the flower before it opens, petals, which often attract animal pollinators, stamens, which include a filament and anther, a sac at the top of each filament that contains male sporangia and releases pollen, and carpels, the female reproductive structures, which include the stigma, the style, and the ovary, a unique angiosperm adaptation that encloses the ovules. Teaching Tips As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. As the text notes, gymnosperm cones are modified shoots and angiosperm flowers represent the remodeling of leaves. These examples of remodeling might be a subject to explore in additional detail as an important lesson in evolution. (17.5–17.6) The authors describe key adaptations of life on land in Module 17.1. Modules 17.2–17.8 describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). (17.3–17.8) Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain free discards by contacting local floral shops and noting educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. (17.6–17.7) Active Lecture Tips See the Activity “Concept Mapping the Alternation of Generations in Angiosperms” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (17.3–17.11) © 2018 Pearson Education, Inc.

Stigma Style Carpel Ovary Anther Stamen Filament Petal Sepal Ovule Figure 17.6b Stigma Style Carpel Ovary Anther Stamen Filament Petal Sepal Figure 17.6b The parts of a flower Ovule Receptacle

17.7 The angiosperm plant is a sporophyte with gametophytes in its flowers The sporophyte is independent, with tiny, dependent gametophytes protected in flowers. Ovules become seeds, and ovaries become fruits. Figure 17.7 illustrates the life cycle of a flowering plant and highlights features that have been especially important in angiosperm evolution. Teaching Tips The authors describe key adaptations of life on land in Module 17.1. Modules 17.2–17.8 describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). (17.3–17.8) Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain free discards by contacting local floral shops and noting educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. (17.6–17.7) Active Lecture Tips See the Activity “Concept Mapping the Alternation of Generations in Angiosperms” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (17.3–17.11) © 2018 Pearson Education, Inc.

Video: Flowering Plant Life Cycle (time lapse) © 2018 Pearson Education, Inc.

Animation: Seed Development © 2018 Pearson Education, Inc.

Animation: Plant Fertilization © 2018 Pearson Education, Inc.

17.8 The structure of a fruit reflects its function in seed dispersal Fruits are ripened ovaries of flowers and adaptations that help disperse seeds. Seed dispersal mechanisms include wind, hitching a ride on animals, or fleshy, edible fruits that attract animals, which then deposit the seed in a supply of natural fertilizer at some distance from the parent plant. Teaching Tips The inspiration for the invention of Velcro came from the attachment mechanism of seeds to a dog like those in Figure 17.8. Search “Velcro biomimicry” on the Internet to find many related sites. (17.8) The authors describe key adaptations of life on land in Module 17.1. Modules 17.2–17.8 describe how these adaptations distinguish the main lineages of the plant kingdom. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). (17.3–17.8) The symbiotic relationships between angiosperms and animals are extensive. Challenge students to list all of the ways that plant reproduction benefits from animals (examples include the role of nectar in attracting pollinators, seed dispersal in fruit, and hitchhiker strategies such as that revealed in Figure 17.8). Not all animals benefit from these relationships. (17.8, 17.10) Active Lecture Tips See the Activity “Concept Mapping the Alternation of Generations in Angiosperms” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (17.3–17.11) Before lecturing on the examples of angiosperm and animal cooperation, let your students work in pairs to try to name as many as they can. (17.8–17.10)

Fruit Seed dispersal Figure 17.8a–c Seed dispersal

Animation: Fruit Development © 2018 Pearson Education, Inc.

17.12 Fungi absorb food after digesting it outside their bodies Fungi are heterotrophic eukaryotes that acquire their nutrients by absorption. A fungus usually consists of a mass of threadlike filaments called hyphae, which branch repeatedly as they grow, forming a mycelium. The symbiosis between fungi and plant roots, called a mycorrhiza (plural, mycorrhizae), absorbs phosphorus and other essential minerals from the soil and makes them available to the plant. Student Misconceptions and Concerns Students often view fungi as some type of plant. However, plants and fungi differ in many ways (for example, fungi are not photosynthetic and typically have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group. (17.12–17.19) Teaching Tips The physical relationship between a fungus and its hyphae is generally analogous to a fire hydrant and the underground water pipes. Only the fire hydrant emerges above the surface of the ground. (17.12) Ask your students to distinguish between fungi and animals. Both are multicellular heterotrophs lacking cellulose. Students will have to dig a little deeper to discover that fungi have cell walls composed of chitin. You might further challenge them to identify animals that also absorb their nutrients directly from their environments (for example, tapeworms). (17.12) The mechanism of natural selection depends in part on the overproduction of offspring. A single mushroom can release as many as 1 billion spores. In addition to facilitating reproduction, such overproduction also increases the likelihood of dispersal. (17.12) Active Lecture Tips The ecological and medical significance of fungi is often underappreciated by students. Ask your students to work in pairs to create a list of the many medical and ecological relationships fungi have with humans. Such assessments can generate increased student interest and help you evaluate their background knowledge. (17.12–17.19)

Reproductive structure Hyphae Spore-producing structures Figure 17.12b Reproductive structure Hyphae Spore-producing structures (tips of hyphae) Figure 17.12b Fungal reproductive and feeding structures Mycelium

FUNGI DIVERSITY Mushrooms A puffball Shelf fungi Figure 17.14e Basidiomycetes (club fungi) Shelf fungi

17.15 Fungi have enormous ecological benefits supply essential nutrients to plants through symbiotic mycorrhyizae, along with prokaryotes are essential decomposers in ecosystems, breaking down organic matter and restocking the environment with vital nutrients essential for plant growth, and may also be used to digest petroleum products to clean up oil spills and other chemical messes. Student Misconceptions and Concerns Students often view fungi as some type of plant. However, plants and fungi differ in many ways (for example, fungi are not photosynthetic and typically have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group. (17.12–17.19) Active Lecture Tips The ecological and medical significance of fungi is often underappreciated by students. Ask your students to work in pairs to create a list of the many medical and ecological relationships fungi have with humans. Such assessments can generate increased student interest and help you evaluate their background knowledge. (17.12–17.19) Students are unlikely to appreciate the many roles that fungi play in natural environments including causing human diseases, bioremediation, and the production of drugs, alcoholic beverages, baked goods, and fuel. To increase student interest, consider starting your lectures on fungi by noting some of the ways that fungi impact human life. Also, consider outside-of-class student assignments to investigate specific roles of fungi that may be of particular interest to students with medical, agricultural, environmental, or industrial majors. (17.15–17.19)

17.17 Lichens are symbiotic associations of fungi and photosynthetic organisms Lichens are symbiotic associations of millions of microscopic green algae or cyanobacteria held in a mass of fungal hyphae. Student Misconceptions and Concerns Students often view fungi as some type of plant. However, plants and fungi differ in many ways (for example, fungi are not photosynthetic and typically have cell walls made of chitin instead of cellulose). Emphasize these basic differences early in your lectures to clearly distinguish fungi as a separate group. (17.12–17.19) Teaching Tips Wonderful coverage of lichens can be found at the aptly named www.lichen.com/. (17.17) In the 21 July 2016 issue of Science, Spribille et al. note that the assumed one lichen-one fungus relationship may not be typical. They found that in addition to the expected ascomycete and photosynthesizing partner, lichens also typically include a basidiomycete yeast. The title of the article is “Basidiomycete yeasts in the cortex of ascomycete macrolichens.” http://science.sciencemag.org/content/early/2016/07/20/science.aaf8287 (17.17) Active Lecture Tips The ecological and medical significance of fungi is often underappreciated by students. Ask your students to work in pairs to create a list of the many medical and ecological relationships fungi have with humans. Such assessments can generate increased student interest and help you evaluate their background knowledge. (17.12–17.19) Students are unlikely to appreciate the many roles that fungi play in natural environments including causing human diseases, bioremediation, and the production of drugs, alcoholic beverages, baked goods, and fuel. To increase student interest, consider starting your lectures on fungi by noting some of the ways that fungi impact human life. Also, consider outside-of-class student assignments to investigate specific roles of fungi that may be of particular interest to students with medical, agricultural, environmental, or industrial majors. (17.15–17.19)

OBJECTIVES You should now be able to Describe the key plant adaptations to life on land. Describe three key events in the evolutionary history of the plant kingdom. Describe the alternation of generations life cycle. Compare the life cycles of a moss and a fern. Explain how pollen and seeds are key adaptations to life on land. Describe the parts of a flower and their functions. Describe the stages of the angiosperm life cycle.

You should now be able to Describe angiosperm adaptations that promote seed dispersal. Explain how flowers are adapted to attract pollinators. Describe the positive ecological and practical roles of fungi. Describe the characteristics of lichens. Explain how fungi help plants.