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CHAPTER 23 Introduction to Plants Quick Review Answer the following without referring to earlier sections of your book. 1. Describe the process of mitosis. (Chapter 6, Section 3) 6E 2. Describe the process of meiosis. (Chapter 7, Section 1) 6E 3. Identify life cycles that have a gametophyte and life cycles that have a sporophyte. (Chapter 7, Section 2) 13B 4. Describe the role of mycorrhizae. (Chapter 12, Section 3 and Chapter 22, Section 3.) 5. List the characteristics of the kingdom Plantae. (Chapter 19, Section 3) 8C TAKS 2 Did you have difficulty? For help, review the sections indicated. Reading Activity Before you begin to read this chapter, survey each section and identify any subtitles, headings, and captions that signal the topic of discussion. As you read, locate other words in the body of the text that signal the sequential pattern. Looking Ahead Show students pictures or live specimens of several plants from different phyla. Ask students to point out the similarities and differences between the groups of plants. On the board or overhead projector, develop a chart organizing the characteristics that students point out. Quick Review Answers Section 1 Adaptations of Plants Establishment of Plants on Land Vascular Tissue, Seeds, and Flowers Plant Life Cycles Section 2 Kinds of Plants Nonvascular Plants Seedless Vascular Plants Gymnosperms Angiosperms Section 3 Plants in Our Lives Plants as Food Cereals Nonfood Uses of Plants www.scilinks.org National Science Teachers Association sci LINKS Internet resources are located throughout this chapter. Plants provide us with the food and oxygen that make life possible. They enrich our lives with beauty and sweet scents. Plants also provide buildings, paper, furniture, clothing, and medicines. Opening Activity 501 Bio 3D Describe the connection between biology and Bio 8A Collect and classify organisms at several taxo- future careers. Bio 3F Research and describe the history of biology and contributions of scientists. Bio 5A Compare cells from different parts of plants and animals including roots, stems, leaves, epithelia, muscles, and bones to show specialization of structure and function. Bio 6E Compare the processes of mitosis and meiosis and their significance to sexual and asexual reproduction. nomic levels such as species, phylum, and kingdom using dichotomous keys. Bio 10C Analyze and identify characteristics of plant systems and subsystems. Bio 11C Analyze the importance of nutrition, environmental conditions, and physical exercise on health Bio 13B Survey and identify methods of reproduction, growth, and development of various types of plants. 1. During mitosis, chromosomes line up along the equator of the dividing cell and the chromatids are pulled apart, with matching chromosomes going to each new cell. Bio 6E 2. In meiosis, a single cell undergoes two divisions to produce four gamete cells, each with only one set of chromosomes. During the first division of meiosis, homologous chromosome pairs line up side-by-side at the equator. These pairs are separated in the first division. The rest of the process is like mitosis. Bio 6E 3. Plants, algae, and some protists have life cycles with a diploid phase called the sporophyte and a haploid phase called the gametophyte. Bio 13B 4. Mycorrhizae obtain mineral nutrients from the soil that are used by the plant, and the plant provides carbohydrates that are used by the mycorrhizae. 5. Plants are photosynthetic organisms with vascular tissue. Plant cells have walls containing cellulose. Individual plants cannot move from place to place. Plants are the primary producers in terrestrial ecosystems. TAKS 2 Bio 8C Reading Activity Answers Answers will vary but should include general characteristics shared by all plants, the unique features of different groups of plants, and the many ways that humans use plants. Chapter 23 • Introduction to Plants 501 Section 1 Section 1 Adaptations of Plants Focus Establishment of Plants on Land Objectives Overview Before beginning this section review with your students the objectives listed in the Student Edition. This section introduces the adaptations that plants have made to life on land. Students will learn how groups of plants become increasingly well suited for dryer conditions. They will learn the common characteristics of all plants, as well as the characteristics that differentiate vascular from nonvascular plants. Bellringer Ask students to write three things that are important for the survival of an organism on land. (Students should recognize the need for obtaining water and nutrients, the need for maintaining homeostasis in a dry, sunny environment, and the need for reproduction out of water.) Bio 11C Plants are the dominant group of organisms on land, based on weight. The kingdom Plantae is a very diverse group. Individuals range from less than 2 mm across to more than 100 m tall. Most plants are photosynthetic; they produce organic materials from ● Distinguish nonvascular inorganic materials by photosynthesis. A few plant species, like plants from vascular the one shown in Figure 1, live as parasites. Many parasitic plants 13A TAKS 3 plants. cannot photosynthesize. ● Relate the success of Plants probably evolved from multicellular aquatic green algae plants on land to seeds and flowers. 7A 13A TAKS 3 that could not survive on land. Multicellularity enabled plants to develop features that helped them live more successfully on land. ● Describe the basic strucBefore plants could thrive on land, they had to be able to do three ture of a vascular plant things: absorb nutrients from their surroundings, prevent their bod13A TAKS 3 sporophyte. ies from drying out, and reproduce without water to transmit sperm. ● Summarize how plants are adapted to living on land. 7A 13A TAKS 3 Key Terms Absorbing Nutrients cuticle stoma guard cell vascular system nonvascular plant vascular plant seed embryo seed plant flower phloem xylem shoot root meristem Aquatic algae and plants take nutrients from the water around them. On land, most plants take nutrients from the soil with their roots. Although the first plants had no roots, fossils show that fungi lived on or within the underground parts of many early plants. So botanists think that fungi may have helped early land plants to get nutrients from Earth’s rocky surface. Symbiotic relationships between fungi and the roots of plants are called mycorrhizae. Today, about 80 percent of all plant species form mycorrhizae. Preventing Water Loss The first plants lived at the edges of bodies of water, where drying out was not a problem. A watertight covering, which reduces water loss, made it possible for plants to live in drier habitats. This covering, called the cuticle, is a waxy layer that covers the nonwoody aboveground parts of most plants. But like the wax on a shiny car, the cuticle does not let oxygen or carbon dioxide pass through it. Pores called stomata (STOH muh tuh) (singular, stoma) permit plants to exchange oxygen and carbon dioxide. Stomata, which extend through the cuticle and the outer layer of cells, are found on at least some parts of most Figure 1 Rafflesia. The flowers of Rafflesia keithii, of Malaysia, measure almost 1 m across and weigh up to 11 kg (24 lb). The plant, which has no stems or leaves, is parasitic on the roots of grape vines. 502 Chapter Resource File pp. 502–503 Student Edition TAKS Obj 1 Bio/IPC 2B, 2C TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7A TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 12B TAKS Obj 3 Bio 13A TEKS Bio 5A, 7A, 7B, 8C, 12B, 13A TEKS Bio/IPC 2B, 2C Teacher Edition TAKS Obj 1 Bio/IPC 2B, 2C TEKS Bio 5A, 10C, 11C TEKS Bio/IPC 2C 502 • Lesson Plan GENERAL • Directed Reading • Active Reading GENERAL • Datasheet for Quick Lab GENERAL Transparencies TT Bellringer TT Stomata and Guard Cells Chapter 23 • Introduction to Plants Planner CD-ROM • Reading Organizers • Reading Strategies • Occupational Application Worksheet Botanist GENERAL Figure 2 Stomata and guard cells The surface of a leaf has numerous stomata, each of which is surrounded by a pair of guard cells. Teach Guard cells Using the Figure GENERAL Draw students’ attention to Figure 2. Point out the guard cells and the stoma of the leaf. Be sure students understand that the guard cells form the opening that is called a stoma. Tell students that in many species, the majority of stomata are on the lower leaf surfaces. Ask students how this benefits plants. (The lower surface is usually not exposed to direct sunlight. This helps reduce water loss.) Bio 5A, 10C Stoma Spiderwort leaves plants. A pair of specialized cells called guard cells border each stoma, as seen in Figure 2. Stomata open and close as the guard cells change shape. Reproducing on Land SKILL Aquatic algae reproduce sexually when sperm swim through the water and fertilize eggs. The sperm of most plants, however, must be able to move without water. In most plants, sperm are enclosed in a structure that keeps them from drying out. The structures that contain sperm make up pollen. Pollen permits the sperm of most plants to be carried by wind or animals rather than by water. Vocabulary Have students use a dictionary to find the origin of the term stoma. (Stoma comes from the Greek word English Language Learners meaning “mouth.”) Observing the Behavior of Stomata 2B 2C 5A TAKS 1 Observing the Behavior of Stomata You can use nail polish to see that a leaf has many stomata. TAKS 1 Bio/IPC 2B, 2C; Bio 5A, 10C Skills Acquired Analyzing results, making comparisons, drawing conclusions Materials clear nail polish, plant kept in light, plant kept in darkness, two 4–5 cm strips of clear tape, 2 microscope slides, compound microscope Procedure 1. Paint a thin layer of clear nail polish on a 1 ⫻ 1 cm area of a leaf on a plant kept in light. Do the same using a plant kept in darkness. Let the nail polish dry for 5 minutes. 2. Place a 4–5 cm strip of clear tape over the nail polish on each leaf. Press the tape firmly to the nail polish. 3. Carefully pull the tape off each leaf. Stick each piece of tape to a microscope slide. Label it appropriately. 4. View each slide with a microscope, first under low power and then under high power. Analysis 1. Describe any differences in the stomata of the two plants. 2. Critical Thinking Drawing Conclusions Which plant will lose water more quickly? Explain. 5. Draw and label what you see on each slide. 503 IPC Benchmark Mini-Lesson Biology/IPC Skills TAKS 1 Bio/IPC 2C Organize, analyze, evaluate ... data. Activity Have students create a dichotomous key for identifying the different types of plants found in this chapter. BUILDER did you know? Pine Stomata Pine trees often have sunken stomata. This adaptation helps them conserve water, an important ability for plants growing in cold climates. Many pine trees grow where the soil freezes and the winds are dry. Bio 5A, 10C Teacher’s Notes Instruct students to put the nail polish on the lower leaf surface because there will likely be more stomata there. Tell students that the nail polish is used to make an impression of the leaf surface and may also remove some of the cells on the leaf’s surface. Answers to Analysis 1. The students should note that the plant kept in the light has more open stomata. 2. The plant kept in the light will lose water more quickly because it has more open stomata. While this seems inefficient for for preventing water loss, the stomata must be open during the day to allow photosynthesis to occur. Chapter 23 • Introduction to Plants 503 Vascular Tissue, Seeds, and Flowers Teach Teaching Tip GENERAL www.scilinks.org Topic: Vascular Plants Keyword: HX4182 Tall Tendencies Ask students to brainstorm and suggest characteristics that would enable plants to grow tall. (a vascular system to carry water and nutrients; rigid cell walls to provide support; thickened stems) Ask students to speculate on the advantages of increased plant height. (Tall plants are able to obtain more sunlight due to reduced competition and shade. Tall plants are also able to send their pollen and fruit/seeds over greater distances than shorter plants.) Advantages of Conducting Tissue The first plants were small. Materials were transported within their bodies by osmosis and diffusion. Today, most plants have strands of specialized cells that transport materials. These specialized cells are connected end to end like the sections in a pipeline, as shown in Figure 3. Some strands carry water and mineral nutrients from the roots to the leaves. Other strands carry organic nutrients from the leaves to wherever they are needed. Specialized cells that transport water and other materials within a plant are found in vascular tissues. The existence of vascular tissue allowed for larger and more-complex plants. The larger, morecomplex plants have a vascular system, a system of well-developed vascular tissues that distribute materials more efficiently. Three groups of plants alive today lack a vascular system. These relatively small plants that have no vascular system are called nonvascular plants. Plants that have a vascular system are called vascular plants. LS Intrapersonal Co-op Learning TAKS 3 Bio 13A, 13B; Bio 5A, 10C Activity GENERAL Seed Dispersal Bring a variety of fruits and cones containing seeds to class. Include some large colorful fruits (apples, oranges, grapes); some small fruits with wings (elm, maple) or umbrella-like appendages (dandelion); some cones with scales (pine, spruce, fir); and a coconut. Ask students to examine the fruits and cones and identify which of the fruits are dispersed by the wind. (winged fruits or small fruits with appendages, conifer seeds) Ask students which seeds are likely dispersed by animals. (showy, fleshy fruits) Ask students how the coconut is dispersed. (By water, since the coconut can float along coasts and from island to island.) LS Visual As plants adapted to land, they developed many features that helped in their success. There was no basic difference in structure between the aboveground and underground parts of the earliest plants. Later plants, however, had roots, stems, and leaves. One of the most important changes in plants was the development of conducting tissues that move water and other materials through the plant body. Advantages of Seeds After vascular tissue, the seed was the next important adaptation to appear in plants. A seed is a structure that contains the embryo of a plant. An embryo is an early stage in the development of plants and animals. Most plants living today are seed plants —vascular plants that produce seeds. The first seed plants appeared about 380 million years ago. Seeds offer a plant’s offspring several survival advantages, which are summarized in Figure 4. Figure 3 Vascular tissue. Thick-walled, tubular cells like these carry water from the tips of roots to the tips of leaves. Stacked end to end, these cells form tiny pipes called vessels. TAKS 2 Bio 8C; TAKS 3 Bio 13A Transparencies TT Vascular Tissue TT Structure of a Vascular Plant TT Structure and Function of Seeds pp. 504–505 Student Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 13A TEKS Bio 7B, 8C, 13A Teacher Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7A, 13A TEKS Bio 5A, 7A, 8C, 10C, 13A, 13B 504 504 EARTH SCIENCE CONNECTION Students may be surprised to learn that the tallest trees on Earth are in California. They are the coast redwoods (Sequoia sempevirens), which can grow more than 110 m (360 ft). The tallest flowering plant is the Australian eucalyptus (Eucalyptus regnans), which has been measured at 84 m (275 ft). The next tallest tree is the giant sequoia (Sequiadendron giganteum) of California, which can reach 76 m (250 ft). TAKS 2 Bio 8C Chapter 23 • Introduction to Plants The seedless vascular plants were the most common plants on Earth about 300 million years ago. Many of these were very large trees, including a number of different tree ferns. When these plants died, their bodies became buried and only partly decomposed. The remains of their tissues formed underground coal deposits. People have dug up many of these carbon-rich deposits and burned the coal as a fossil fuel. The period of time in Earth’s history when these plants were most abundant is called the Carboniferous period. Figure 4 Structure and function of seeds The structure of a seed helps it to perform its functions. Pine seedling Teaching Tip Stored food Wing Pine cone Pine seed Seed coat Embryo Seeds The seed coat of a pine seed covers and protects the embryo. The stored food supply will nourish the embryo as it starts to grow. A wing helps pine seeds disperse. 1. Protection. Seeds are surrounded by a protective cover called the seed coat. The seed coat protects the embryo from drying out and from mechanical injury and disease. 2. Nourishment. Most kinds of seeds have a supply of nutrients stored in them. These nutrients are a ready source of nourishment for a plant embryo as it starts to grow. Pine seeds may not germinate for several years. www.scilinks.org Topic: Structure and Function of Seeds Keyword: HX4169 TAKS 2 Bio 8C; TAKS 3 Bio 13A; Bio 13B Group Activity 3. Plant dispersal. Seeds disperse (spread) the offspring of seed plants. Many seeds have structures that help wind, water, or animals carry them away from their parent plant. Dispersal prevents competition for water, nutrients, light, and living space between parents and offspring. 4. Delayed growth. The embryo in a seed is in a state of suspended animation. Most seeds will not sprout until conditions are favorable, such as when moisture is present and the weather is warm. Thus, seeds make it possible for plant embryos to survive through unfavorable periods such as droughts or cold winters. Advantages of Flowers The last important adaptation to appear as plants evolved was the flower, a reproductive structure that produces pollen and seeds. Flowers make plant reproduction more efficient. The pollen of the first seed plants was carried by wind. Large amounts of pollen are needed to ensure cross-pollination by wind—an inefficient system. Most plants living today are flowering plants—seed plants that produce flowers. The first flowering plants appeared more than 130 million years ago. Many flowers attract animals, such as insects, bats, and birds. As Figure 5 shows, tiny pollen grains stick to animals, which carry pollen directly from one flower to another. Flowering plants that are pollinated by animals produce less pollen, and cross-pollination can occur between individuals that live far apart. GENERAL Durability of Seeds Tell students that seeds are adapted for survival in a wide variety of climates. Emphasize that seeds can survive in a dormant state if conditions are unfavorable for growth. Have students speculate about why so many seedlings appear after forest fires. (Fire clears the accumulated leaf litter on the forest floor. Many seeds need contact with bare mineral soil to germinate. Fire also opens some cones to allow seeds to fall out and germinate. Fire may also eliminate shade, allowing light to reach the forest floor and stimulate germination.) Figure 5 Pollination. This honeybee is covered with pollen grains containing the sperm of the plant it has just visited. The bee will transfer some of the pollen to the next flower it visits. Observing Pollen Grain Have students work in groups of two or three. Have students make wetmount slides of pollen from pine trees or observe prepared slides of pine pollen. Then have them draw and label the pollen grains and estimate their size based on the field of view. If possible, have students compare the pollen from several different species. Then have students examine the pollen from angiosperms, and compare the pollen structure of different groups. If pollen is not in season, use prepared slides or pollen from nursery grown flowers. Have groups prepare posters of the different pollen structures. LS Visual TAKS 2 Bio 8C; Bio 13B 505 IPC Benchmark Review To prepare students for the TAKS and accompany the discussion of stomata, have students review Response to Pressure and Temperature TAKS 4 IPC 7A on p. 1049 of the IPC Refresher in the Texas Assessment Appendix of this book. did you know? Attractive Orchids Orchids have highly elaborate ways of attracting pollinators. One orchid species has a flower that resembles a female wasp. Male wasps pick up some pollen while trying to mate with the modified petals. In another species, the flower holds a small pool of water. When a bee tries to collect nectar, it falls into the water and can escape only through a narrow passageway that forces the bee to brush against the pollen-bearing anthers. TAKS 3 Bio 7A (grade 11 only); Bio 13B Chapter 23 • Introduction to Plants 505 Plant Life Cycles Teach, continued continued Teaching Tip Life Cycle Review Ask students the following questions: How do scientists represent the chromosome number of a gametophyte? (n, or haploid) How do scientists denote the chromosome number of the sporophyte? (2n, or diploid) What is the name of the first sporophyte cell? (zygote) What process produces a zygote? (fertilization) What is the name of the first gametophyte cell? (spore) What process produces spores? (meiosis) TAKS 2 Bio 8C; Bio 6E, 13B Using the Figure GENERAL Draw students’ attention to Figure 7. Have students compare the relative sizes of sporophytes and gametophytes in the moss and the flowering plant. (Students should notice that the moss sporophyte is smaller than the gametophyte, while the flowering-plant gametophyte is considerably smaller than the flowering-plant sporophyte.) In many algae, the zygote is the only diploid (2n) cell. It undergoes meiosis right after fertilization. So the bodies of these algae consist of haploid cells. In the ancestors of plants, however, meiosis was delayed. The zygote divided by mitosis and grew into a multicelled sporophyte that was diploid and produced haploid (n) spores by Figure 6 Alternation of meiosis. The spores grew into multicelled gametophytes that were generations. In the life cycle haploid and produced gametes by mitosis. As a result, plants have of a plant, a diploid sporophyte life cycles in which haploid plants that make gametes (gametogeneration alternates with a haploid gametophyte phytes) alternate with diploid plants that make generation. spores (sporophytes). A life cycle in which a gametophyte alternates with a sporophyte is called alterDiploid (2n) Haploid (n) nation of generations. The basic plant life cycle is shown in Figure 6. n Spore-forming cell Unlike the green algae with alternation of generan Spores Meiosis tions, plants have gametophytes and sporophytes n 2n that look very different. In addition, the relative n sizes of gametophytes and sporophytes changed as plants evolved, as Figure 7 shows. In nonvascular 2n n n plants, such as mosses, the gametophyte generation Sporophyte Gametophytes is dominant (most noticeable). In vascular plants, such as the flowering plants, the sporophyte genMitosis eration is dominant. Like the presence of a vascular 2n system, the relative sizes of gametophytes and n Zygote sporophytes is a fundamental difference between n Fertilization Gametes the nonvascular plants and the vascular plants. Figure 7 Nonvascular plants versus vascular plants Gametophytes and sporophytes vary greatly in size. The gametophytes form inside a flower. LS Visual Bio 13B Sphagnum moss A sporophyte grows atop a gametophyte. C24 000 007b 506 REAL WORLD CONNECTION pp. 506–507 Student Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7A TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 13A TEKS Bio 7A, 7B, 8C, 13A Teacher Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 13A TEKS Bio 6E, 7A, 7B, 8C, 13A, 13B 506 Pollen allergies are commonly known as “hay fever.” Such allergies are actually reactions to proteins found on the outside of the pollen grains. Different pollens cause allergies in different people because each type of pollen has a different protein in the coats of its pollen grains. Chapter 23 • Introduction to Plants Tomato sporophytes The Vascular-Plant Sporophyte As the size of plant sporophytes increased, so did the complexity of their structure. An increase in size enables cell specialization and, therefore, the development of complex tissues and specialized structures. The following features characterize the sporophytes of most vascular plants. Close Reteaching Vascular System Larger bodies require an efficient vascular system for transporting materials internally. The sporophytes of vascular plants have a vascular system with two types of vascular tissue. Each type of vascular tissue contains strands of long, tubelike cells that are lined up end to end like sections of pipe. These strands of cells transport water and nutrients within a plant’s body. Relatively soft-walled cells transport organic nutrients in a kind of tissue called phloem (FLOH uhm). Hard-walled cells transport water and mineral nutrients in a kind of tissue called xylem (ZIE luhm). The walls of the water-conducting cells in xylem are thickened, which helps support the Shoot meristem plant body. This makes it possible for vascular plants to grow to great heights. Co-op Learning English Language Learners Quiz GENERAL 1. True or false: nonvascular plants Leaf Distinctive Body Form Nearly all plants have a body that consists of a vertical shaft from which specialized structures branch, as shown in Figure 8. The part of a plant’s body that grows mostly upward is called the shoot . In most plants, the part of the body that grows downward is called the root. Zones of actively dividing plant cells, called meristems (MEHR uh stehmz), produce plant growth. The vertical body form results as new cells are made at the tips of the plant body. As vascular plants became better adapted to life on land, most developed the familiar plant structures—roots, stems, and leaves—which are complex structures made of several different types of specialized tissues. Figure 8 Vascular plant sporophyte. The sporophytes of the vast majority of vascular plants have an aboveground shoot with stems and leaves and an underground root. Growth occurs in regions called meristems. Have students work in pairs to review the key terms for this section. Encourage each pair of students to take turns asking and answering questions about the definitions of the terms. LS Verbal contain a well-developed system of tissues that transport water and nutrients. (False. Vascular plants contain transporting tissues.) 2. What is the primary role of flowers? (to promote pollination by increasing its efficiency) Stem Alternative Assessment GENERAL Students should work in pairs to design and create a single poster that illustrates the advantages of vascular seedless plants over nonvascular plants; the advantages of seeds over spores; and the advantages of flowering plants over non-flowering seed plants. Root Root meristem Section 1 Review LS Visual Co-op Learning TAKS 2 Bio 8C; TAKS 3 Bio 13A Summarize how plants are adapted to living Critical Thinking Evaluating Conclusions successfully on land. Why do you think vascular plants are more successful as land plants than are nonvascular 7B 13A plants? 7B 13A Describe two basic differences between nonvas13A cular plants and vascular plants. Critical Thinking Relating Concepts How have seeds and flowers made plants more 7B 13A successful on land? TAKS Test Prep Water loss from most plants is reduced by a waxy layer called the 13A A xylem. C stomata. B phloem. D cuticle. 507 Answers to Section Review 1. The formation of a waxy cuticle, vascular tissues, drought-resistant reproductive structures and seed development are adaptations that enable plants to live on land. TAKS 3 Bio 7B, 13A 2. Vascular plants have a vascular system that transports water, minerals, and sugars throughout the plant; nonvascular plants do not. Nonvascular plant life cycles are dominated by the gametophyte; vascular plants have a dominant sporophyte. TAKS 3 Bio 13A 3. Seeds and flowers have enabled plants to reproduce and disperse offspring without the aid of water. Flowers have enabled plants to produce offspring from fewer numbers of gametes because animals often aid in fertilization. TAKS 3 Bio 7A (grade 11 only), 7B, 13A 4. Vascular plants are more successful on land because adaptations have allowed them to reduce their dependence on water. These include cuticle protected leaves, vascular tissue, roots, taller stems, and drought resistant spores or seeds. TAKS 3 Bio 7B, 13A 5. A. Incorrect. The xylem carries water and minerals throughout vascular plants. B. Incorrect. The phloem carries sugars and organic compounds in vascular plants. C. Incorrect. Stomata are small holes in the leaves of a plant that open to allow gas exchange and close to limit water loss. D. Correct. The waxy cuticle limits evaporation. TAKS 3 Bio 13A Chapter 23 • Introduction to Plants 507 Section 2 Section 2 Kinds of Plants Focus Overview Before beginning this section review with your students the objectives listed in the Student Edition. This section introduces the defining characteristics of the different groups of plants. Students will also identify several examples of each group. These groups include nonvascular plants, vascular seedless plants, gymnosperms, and angiosperms. Bellringer On the board or overhead, write the following headings: Nonvascular, Seedless Vascular, Gymnosperm, Monocot Angiosperm, and Dicot Angiosperm. Ask students to write the headings in their notebook, and place at least one example under each heading. Nonvascular Plants Objectives ● Describe the key features of the four major groups of plants. 13B ● Classify plants into one of the 12 phyla of living plants. 8C TAKS 2 Key Terms rhizoid rhizome frond cone gymnosperm angiosperm fruit endosperm monocot dicot The brilliant green carpet of mosses you see in Figure 9 is made up of thousands of individual plants. Living carpets of mosses are often found near streams, coastlines, and other moist places. But these tough little plants also live in some surprising places, such as cracks in city sidewalks and rocky mountaintops—any place where a little moisture can collect. The moisture makes it possible for these nonvascular plants to survive. Nonvascular plants do not have a vascular system for transporting water and other nutrients within their bodies. This means that all nonvascular plants lack true roots, stems, and leaves, although most have structures that resemble them. True roots, stems, and leaves are complex structures that contain vascular tissues. Key Features of Nonvascular Plants In addition to the lack of true roots, stems, and leaves, nonvascular plants share several other features. These features are key adaptations that have enabled them to survive on land. Figure 9 A carpet of mosses. Mosses grow in tightly packed mats that may contain dozens of plants per square inch. Small Size All nonvascular plants are small and relatively simple. Water and other nutrients are transported within their bodies mostly by osmosis and diffusion, which move materials short distances. This greatly limits the size of a nonvascular plant’s body. Larger Gametophyte The gametophytes of nonvascular plants are larger and more noticeable than the sporophytes. Hairlike projections called rhizoids anchor the gametophytes to the surfaces on which they grow. The smaller, usually nongreen sporophytes grow on the gametophytes and depend on them for nutrients. Motivate Demonstration Bring in living specimens or parts of specimens of a variety of plants. The collection should include as many of the following as possible: moss, liverwort, fern, horsetail, conifer, cycad, ginkgo, a flowering monocot (corn, iris, grass), and a flowering dicot (rose, daisy, tomato, etc.). Ask students to describe and compare the characteristics of each, noting both similarities and differences. (Differences may include size, presence/absence of spores, flowers, fruits, leaf shape, vein patterns, and stiffness.) TAKS 2 Bio 8C Require Water for Sexual Reproduction Non- vascular plants must be covered by a film of water in order for fertilization to occur. Eggs and sperm form in separate structures, which are often on separate plants. The gametophytes grow in mats of tightly packed individuals. When these mats are covered by a film of water, the sperm can easily swim to neighboring individuals and fertilize their eggs. 508 Chapter Resource File pp. 508–509 Student Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 13A TEKS Bio 7B, 8C, 13A, 13B Teacher Edition TAKS Obj 1 Bio/IPC 2B TAKS Obj 2 Bio 8C TEKS Bio 5A, 8C, 10C TEKS Bio/IPC 2B 508 • Lesson Plan GENERAL • Directed Reading • Active Reading GENERAL • Data Sheet for Data Lab GENERAL Transparencies TT Bellringer Chapter 23 • Introduction to Plants Planner CD-ROM • Reading Organizers • Reading Strategies • Portfolio Project Plant Focus GENERAL Kinds of Nonvascular Plants The nonvascular plants include the mosses and the two simplest groups of plants—liverworts and hornworts. Examples of these plants are shown in Figure 10. www.scilinks.org Topic: Nonvascular Plants Keyword: HX4130 Mosses The mosses (phylum Bryophyta) are the most familiar non- Teaching Tip vascular plants. The “leafy” green plants that you recognize as mosses are gametophytes. Moss sporophytes, which are not green, grow from the tip of a gametophyte. Each sporophyte consists of a bare stalk topped by a spore capsule. Most mosses have a cuticle, stomata, and some simple conducting cells. The walls of the water-conducting cells in mosses are not thickened, as they are in a vascular plant. Mosses never get very large because their water-conducting cells carry water only short distances. Liverworts Like the mosses, liverworts (phylum Hepatophyta) grow in mats of many individuals. Liverworts have no conducting cells, no cuticle, and no stomata. Their gametophytes are green. In some species, such as the common liverwort shown in Figure 10, the gametophytes of liverworts are flattened and have lobes. Structures that resemble stems and leaves make up the gametophytes of most liverworts, like those of the mosses. The sporophytes of liverworts are very small and consist of a short stalk topped by a spore capsule. Hornworts The hornworts (phylum Anthocerophyta) are a small group of nonvascular plants that, like the liverworts, completely lack conducting cells. Hornworts have both stomata and a cuticle. The gametophyte of a hornwort is green and flattened. Green hornlike sporophytes grow upward from the gametophytes. The word liverwort combines the familiar word liver and the Old English word wort, meaning “herb.” The word liverwort dates back to the Middle Ages, when it was thought that plants resembling certain body parts could cure diseases of those body parts. There are three phyla of nonvascular plants. Marchantia, a liverwort (Phylum Hepatophyta) GENERAL Mosses Have students observe different types of mosses using a stereomicroscope. They should find both gametophyte and sporophyte stages. Point out that the structures resembling leaves on the moss gametophyte are not considered to be true leaves. Tell students that a leaf is a complex structure that consists of several specialized tissues. Ask them whether they think the sporophyte and gametophyte are photosynthetic. (Only the gametophyte is photosynthetic.) Tell students that the sporophyte is dependent upon the gametophyte for survival. LS Visual TAKS 2 Bio 8C; Bio 5A, 10C SKILL BUILDER Math Skills Have students determine the mass of a small sample of dry sphagnum (peat) moss, which is available at garden centers. Have students record the mass of the dry moss. Next, have them place this sample in a large beaker of water for 10–15 minutes. Tell students that 1kg of dry moss can soak up approximately 25 kg of water. Have students predict the mass of their moss after soaking in water. Have students remove the wet moss from the beaker, and determine its mass. Tell students to compare their findings with their predictions. (The mass of the wet moss should be about 25 times greater than the mass of the dry moss.) TAKS 1 Bio/IPC 2B Figure 10 Nonvascular plants Polytrichum, a moss (Phylum Bryophyta) Teach Anthoceros, a hornwort (Phylum Anthocerophyta) 509 MEDICINE CONNECTION Tell students that moss has been used as an antiseptic for centuries. Even in World War I, moss was used to treat soldier’s wounds in emergency situations. The antiseptic qualities result from moss’ natural absorbency and acidity. MISCONCEPTION ALERT Mistaken Identity A variety of plants and plantlike organisms are mistakenly called mosses. Examples include Irish moss, Spanish moss, and reindeer moss. Show photos of these examples and reinforce the concept that common names can be misleading. For example, Irish moss is a red alga, Spanish moss is a flowering vascular plant, and reindeer moss is lichen. Chapter 23 • Introduction to Plants 509 Seedless Vascular Plants Teach, continued continued Teaching Tip GENERAL Local Habitats If your school grounds contain a number of different habitats, take the students on a tour of the campus. Otherwise, schedule a trip to a nearby park. Ask students to identify the habitats in which nonvascular plants would most likely be found. (moist habitats) Ask where vascular plants would most likely be found. (any habitat) Ask students to try to identify one nonvascular plant and one vascular plant. Have them explain what characteristics they used to determine vascularity. (nonvascular: moist habitat, small size, no flowers or seeds; vascular: any habitat, large or small, leaves with veins) TAKS 2 Bio 8C; TAKS 3 Bio 13A Using the Figure GENERAL Draw attention to Figure 11. Ask students how Cooksonia resembles plants that are alive today. (The upright growth habit of these plants and the location of the reproductive structures resemble modern plants.) Ask students how they differ from the plants they are most familiar with. (These primitive plants have no leaves, roots, flowers, seeds, or fruits.) www.scilinks.org Topic: Seedless Vascular Plants Keyword: HX4161 Vascular plants that do not produce seeds are called seedless vascular plants. The earliest known seedless vascular plant, Cooksonia, is illustrated in Figure 11. The sporophytes of these ancient plants had branched, leafless stems that were only a few centimeters long. Spore-forming sporangia were located at the tips of the stems. Rhynia, another early seedless vascular plant, also had horizontal underground stems, or rhizomes. Key Features of Seedless Vascular Plants Seedless vascular plants are much larger and more complex than the nonvascular plants. Other key features enabled them to spread and adapt to drier habitats on land. Real Life The spores of a common club moss, Lycopodium, form a powder that has several uses. Herbalists use the spores to make a powder for treating skin disorders. The spores are also used to make photographic flash powder. Finding Information Find out how Lycopodium powder is used by the pharmaceutical industry. Vascular System Seedless vascular plants have a vascular system with both xylem and phloem. The water-conducting cells in the xylem are reinforced with lignin, a major part of wood. Because of their vascular system, seedless vascular plants grow much larger than nonvascular plants and also develop true roots, stems, and leaves. Larger Sporophyte The sporophytes of seedless vascular plants are larger than the gametophytes. Their larger size makes it easier for the wind to carry away spores, which makes dispersal more efficient. The much smaller gametophytes of most seedless vascular plants develop on or below the surface of soil. As in the nonvascular plants, water is needed for fertilization. When there is enough water on or in the soil, the sperm swim to eggs and fertilize them. Drought-Resistant Spores The spores of the seedless vascular plants have thickened walls that are resistant to drying. Such spores make it possible for a plant to live in drier habitats. Figure 11 The earliest known vascular plant Cooksonia, the oldest known vascular plant, lived about 410 million years ago. TAKS 2 Bio 8C Model of Cooksonia 510 Cultural Awareness pp. 510–511 Student Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 13A TEKS Bio 7B, 8C, 13A Teacher Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 13A TEKS Bio 5A, 8C, 13A, 13B 510 Edible Seedless Vascular Plants The fiddleheads of ferns found in the forests of the northeastern United States during the spring were considered a delicacy by early Native American groups. Edible fiddleheads are actually the tightly coiled, emerging fronds of the fern, Matteuccia struthiopteris. Today, they are still used in American cuisine. You may want to have interested students research recipes for fiddleheads or prepare some dishes for the class. Chapter 23 • Introduction to Plants Artist’s rendition of Cooksonia Kinds of Seedless Vascular Plants The seedless vascular plants include ferns and three other groups of plants known as fern allies—whisk ferns, club mosses, and horsetails. Like the ferns, the fern allies usually grow in moist places. Demonstration Ferns The ferns (phylum Pterophyta) are the most common and most familiar seedless vascular plants. Ferns grow throughout the world, but they are most abundant in the tropics. The plants you recognize as ferns are sporophytes. Most fern sporophytes have a rhizome that is anchored by roots and leaves called fronds. The coiled young leaves of a fern, shown in Figure 12, are called fiddleheads. Spores are produced in sporangia that grow in clumps on the lower side of fronds. The gametophytes of ferns are flattened, heartshaped green plants that are usually less than 1 cm (0.5 in.) across. Club Mosses Unlike true mosses, the club mosses (phylum Lycophyta), have roots, stems, and leaves. Their leafy green stems branch from an underground rhizome. Spores develop in sporangia that form on specialized leaves. In some species, such as the one seen in Figure 13, clusters of nongreen spore-bearing leaves form a structure called a cone. Figure 12 A fern. This sword fern sporophyte has many fronds and fiddleheads. The inset shows a gametophyte at twice its actual size. Horsetails The horsetails (phylum Sphenophyta) also have roots, stems, and leaves. The vertical stems of horsetails, which grow from a rhizome, are hollow and have joints. Whorls of scalelike leaves grow at the joints. Spores form in cones located at the tips of stems. Bring examples of several kinds of ferns to class, and have students examine them. Also bring some pictures of tree ferns, which are native to many tropical regions. Have students note the shapes of the leaves and any fertile fronds or sori present on the lower surface of the fronds. Point out that there are more than 12,000 species of ferns on Earth today. Among these species we find a tremendous diversity of leaf form (from simple, rounded leaves to lacy fronds with hundreds of leaflets); plant shape (moss-like to tree form); and plant size (2.5 cm to 20 m tall). LS Visual TAKS 2 Bio 8C; Bio 5A Activity Use a fern leaf from the demonstration above. Show students the clusters of sporangia (sori) on the lower surface of a frond. Let them remove a sorus and crush it on white paper using the eraser end of a pencil. Next, have them sprinkle some spores on a moist peat pellet and place the peat pellet in a sealed jar. The first structures they will observe will be the little green heart-shaped gametophytes. Whisk Ferns The whisk ferns (phylum Psilotophyta) probably most closely resemble the earliest vascular plants. Whisk ferns have highly branched stems and no leaves or roots. They produce spores in sporangia that form at the tips of short branches. Figure 13 Fern allies In addition to ferns, there are three other living phyla of seedless vascular plants that are known as fern allies. LS Kinesthetic Bio 5A, 13B READING SKILL BUILDER Psilotum, a whisk fern (Phylum Psilotophyta) Lycopodium, a club moss (Phylum Lycophyta) Equisetum, a horsetail (Phylum Sphenophyta) 511 Cultural Awareness Introduced Species Can Replace Native Species Cultures that spread to new regions of the Earth often bring familiar plant and animal species with them, sometimes with disastrous results. Settlers introduced pigs on the island of Hawaii as a source of food, but these animals wiped out native vegetation. Additionally, the settlers brought their own plants, which eventually crowded out native species. The people of Hawaii are now trying to reclaim their native plants, including tree ferns. Have students research introduced plants in their own area that are threatening native plant communities. Reading Organizer Encourage students having difficulty to use the information on this page to make a chart that outlines the differences between ferns, club mosses, horsetails, and whisk ferns. English language learner students may want to fill in the chart in their English Language Learners native language. TAKS 2 Bio 8C Chapter 23 • Introduction to Plants 511 Gymnosperms Gymnosperms (JIHM noh spurmz) are seed plants whose seeds do not develop within a sealed container (a fruit). The word gymnosperm comes from the Greek words gymnos, meaning “naked,” and sperma, meaning “seed.” Teach, continued continued Activity GENERAL Gymnosperms are among the most successful groups of plants. The following key features have made them successful on land. Seeds All gymnosperms produce seeds. Seeds protect plant Figure 14 Juniper pollen. This juniper, a type of gymnosperm, releases clouds of pollen in late fall or early winter. Analyzing the Effect of Climate on Plants 0100010110 011101010 0010010001001 1100100100010 0000101001001 1101010100100 0101010010010 water to reach and fertilize eggs. Instead, the sperm are carried to the structures that contain eggs by pollen, which can drift on the wind, as seen in Figure14. Wind pollination makes sexual reproduction possible even when conditions are very dry. Teacher’s Notes Point out that the bar graph represents precipitation and that the line graph represents temperature. 1. Answers may vary. Anchorage temperatures average at or below freezing for six months of the year. Precipitation is highest in summer and fall, and relatively low in other seasons. 2. Answers should predict that the taiga shares a similar plant community, the taiga outside of Anchorage should have a fairly similar climate. 3. Yes. Explanations should rely on the map for reasoning. The taiga species are not found further north or south. Soil type or human activities are also valid explanations. TAKS 1 Bio/IPC 2A Analyzing the Effect of Climate on Plants 2C 13A 0100010110 011101010 0010010001001 1100100100010 0000101001001 1101010100100 0101010010010 Background The map at right shows the taiga of North America. The taiga is a vast forest of conifers, a type of gymnosperm. The graph shows average annual temperature and precipitation data for Anchorage, Alaska, which is located at the western edge of the taiga. Use the map and graph to answer the following questions. 1. Describe the climate of Anchorage, Alaska. 2. Critical Thinking Predicting Patterns What type of climate would you expect to find in other parts of the taiga? 512 Student Edition TAKS Obj 1 Bio/IPC 2C TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 13A TEKS Bio 7B, 8C, 13A TEKS Bio/IPC 2C Teacher Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7A TEKS Bio 3D, 7A, 8A, 8C Chapter 23 • Introduction to Plants 60° N TAKS 1, TAKS 3 Analysis pp. 512–513 512 Greatly Reduced Gametophytes All seed plants produce very tiny gametophytes of two types—male and female. The gametophytes form within the tissues of the sporophytes. Grains of pollen are male gametophytes. Female gametophytes form within structures that become seeds. In all but one species of gymnosperm, male and female gametophytes develop in male and female cones, respectively. Wind Pollination The sperm of gymnosperms do not swim through TAKS 3 Skills Acquired Bio 13A Analyzing data, interpreting graphs, drawing conclusions Answers to Analysis embryos, provide them with nutrients, and permit them to survive long periods of unfavorable conditions. In some plants, seeds also disperse new plants far from their parents. 3. Critical Thinking Drawing Conclusions Does climate appear to be an important factor in where the conifers of the taiga grow? Explain. 30° N Taiga Anchorage, Alaska 40 20 30 0 20 –20 10 –40 –60 0 J FMAMJ J ASOND Months Temperature (°C) TAKS 2 Bio 8C; Bio 8A Key Features of Gymnosperms Precipitation (cm) Conifer ID Obtain cuttings of several conifers. Then have students construct their own keys, which they can use to identify the species. Students may look at cones, needle size, needle shape, needle organization, and needle color. Then supply students with keys or field guides and ask them to correctly identify their samples. LS Kinesthetic Kinds of Gymnosperms Four groups of living seed plants are referred to as gymnosperms—conifers, cycads, ginkgo, and gnetophytes. Examples of each of these four groups are shown in Figure 15 and Figure 16. READING SKILL BUILDER Conifers The conifers (phylum Coniferophyta) are the most familiar, and most successful, gymnosperms. Conifers have leaves that are either needle-like or reduced to tiny scales, as Figure 15 shows. These leaves are an adaptation for limiting water loss. Some of the tallest living plants, the redwoods of coastal California and Oregon, are conifers. The oldest trees in the world are thought to be bristlecone pines, another species of conifer that grows in the Rocky Mountains. Some bristlecone pines are about 5,000 years old. Vast forests of conifers grow in cool, dry regions of the world. Cycads The cycads (phylum Cycadophyta) have short stems and palmlike leaves. Cones that produce pollen and those that produce seeds develop on different plants. Cycads are widespread throughout the tropics. Figure 15 Juniper leaves and cones. The tiny scalelike leaves of junipers—a type of conifer—are an adaptation that limits water loss. The blue, berrylike structures are the female cones of this juniper. Discussion Lead the class in brainstorming the characteristics they have observed in pine trees. (They stay green all year; have thin, needle-like leaves; have pinecones.) Stress that while this section provides additional information about gymnosperms, students already know a great deal about them. Encourage English language learners to translate the list into their English Language Learners native language. Career Ginkgo The only living species of ginkgo (phylum Ginkgophyta), or maidenhair tree, has fan-shaped leaves that resemble the leaves of the maidenhair fern. The male and female gametophytes of ginkgo develop on separate trees. Ginkgo seeds do not develop within a cone. Botanist A botanist studies plants and their environments. Most botanists specialize in a particular area. For example, plant physiologists study the structural parts of plants and how they function; plant breeders study the ways in which plants reproduce and how their traits are inherited’ horticulturists work with crops such as flowers, fruits, and vegetables; agronomists work with crops such as grains and dry beans; and foresters study all aspects of tree growth. Have students research a field of botany that interests them and prepare a written report on career opportunities in that field. Gnetophytes The gnetophytes (phylum Gnetophyta) are a diverse group of trees, shrubs, and vines that produce pollen and seeds in cones that resemble flowers. One type of gnetophyte, Ephedra, is common in the western United States. Figure 16 Other gymnosperms In addition to conifers, there are three other living phyla of gymnosperms. Bio 3D Encephalartos, a cycad (Phylum Cycadophyta) Leaves and seeds of Ginkgo (Phylum Ginkgophyta) Ephedra (Mormon tea), a gnetophyte (Phylum Gnetophyta) 513 MISCONCEPTION ALERT Supplements made from Ginkgo biloba and other plants are commonly sold in grocery, drug, and health food stores. Students may think that a substance called an herbal supplement is not a drug. In fact, many herbal supplements act as drugs, though they are not regulated by the Food and Drug Administration. Have students examine advertisements for common herbal supplements and infer which claims could be substantiated experimentally and which claims are more difficult to verify. Bio 3B did you know? Living Fossils The ginkgo, or maidenhair tree, is considered a “living fossil” because it was once thought to be extinct. The ginkgo is the only broadleaf gymnosperm still surviving, and it closely resembles fossil specimens. In 1994, another gymnosperm thought to be extinct for 100 million years was discovered in a rain forest near Sydney, Australia. A small population of Wollemi pines, a prehistoric type of conifer belonging to a family that was thought to have become extinct along with the dinosaurs, was found by a park ranger. This ancient family of trees once spread into the Northern Hemisphere. TAKS 2 Bio 7A (grade 11 only) Chapter 23 • Introduction to Plants 513 Angiosperms Teach, continued continued Demonstration GENERAL Most seed plants are flowering plants, or angiosperms (AN jee oh spurmz). Angiosperms produce seeds that develop enclosed within a specialized structure called a fruit, as seen in Figure 17. The word angiosperm comes from the Greek words angeion, meaning “case,” and sperma, meaning “seed.” www.scilinks.org Topic: Angiosperms Keyword: HX4007 Bring several examples of cones (pine, spruce, fir, yew) and flowers (iris, daisy, gladiolus, etc) to class, and have students examine and compare each of these types of reproductive structures. (Both produce seeds; flowers have petals, stamens, and pistils, and cones do not; cones have scales.) LS Visual Key Features of Angiosperms Angiosperms are the most recent group of plants to evolve. The following key features made them the most successful group of plants. Flowers The male and female gametophytes of angiosperms develop within flowers, which promote pollination and fertilization more efficiently than do cones. Some flowers, such as roses, are brightly colored or have strong scents. This attracts insects and other animals that carry pollen and increases the likelihood of crosspollination. Other flowers, such as garden peas, are adapted for selfpollination, which often occurs before the flowers open. The flowers of many angiosperms, such as oaks and grasses, have small greenish flowers that are adapted for wind pollination. The female reproductive part of a flower also provides a pathway that enables sperm to reach and fertilize eggs without swimming through water. Bio 5A, 13B Teaching Tip GENERAL Charting Information Have students make a Graphic Organizer similar to the one at the bottom of this page to compare and contrast the characteristics of the major plant groups. Ask students to illustrate their graphic organizer with a drawing of a plant in each of the major groups. LS Kinetic TAKS 1 Bio/IPC 2C; TAKS 2 Bio 8C Fruits Although fruits provide some protection for developing seeds, their primary function is to promote seed dispersal. The angiosperms produce many different types of fruits, which develop from parts of flowers. Many fruits are eaten by animals. The seeds are dispersed as they pass undigested from the animals’ bodies. Other fruits have structures that help them float on wind or water. Some fruits even forcefully eject their seeds, flinging them away from the parent plant. www.scilinks.org Topic: Texas Desert Plants Keyword: HXX4013 Endosperm The seeds of angiosperms have a supply of stored food called endosperm at some time during their development. In many angiosperms, the endosperm is absorbed by the embryo before the seeds mature. Transparencies TT Life Cycle of an Angiosperms TT Familiar Families of Angiosperms Figure 17 Seeds in a fruit. These melons, which contain seeds, are the fruits of an angiosperm. 514 Graphic Organizer pp. 514–515 Student Edition TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 13A TEKS Bio 7B, 8C, 13A, 13B Teacher Edition TAKS Obj 1 Bio/IPC 2C TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 13A TEKS Bio 5A, 8A, 8C, 10C, 13A, 13B TEKS Bio/IPC 2C 514 Use this graphic organizer with Teaching Tip on this page. Phylum Liverworts Mosses Ferns Conifers Flowering plants Chapter 23 • Introduction to Plants Vascular system Roots Seeds Flowers Dominant gametophyte Dominant sporophyte ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ Kinds of Angiosperms Figure 18 A monocot and a dicot Botanists divide the angiosperms into two subgroups—monocots and dicots as Figure 18 shows. The monocots are flowering plants that produce seeds with one seed leaf (cotyledon). Most monocots also produce flowers with parts that are in multiples of three and have long, narrow leaves with parallel veins. The dicots are flowering plants that produce seeds with two seed leaves. Most dicots also produce flowers with parts in multiples of two, four, or five and have leaves with branching veins. Table 1 lists examples of some of the most familiar families of angiosperms. Monocots and dicots differ in several ways. Activity Classifying Plants as Monocots or Dicots Provide examples and pictures of a variety of plants, including both dicots and monocots. Let students determine whether the examples are dicots or monocots. Point out that some plants are not easily placed into one of the groups, such as pothos ivy. Botanists usually rely on flower structure in such cases. LS Visual Roses are dicots. Daylilies are monocots. TAKS 2 Bio 8C; Bio 13B Close Table 1 Familiar Families of Angiosperms Subgroup Monocots (class Monocotyledonae) Dicots (class Dicotyledonae) Family Reteaching Examples Iridaceae (iris) Irises, gladiolus, crocus, blue-eyed grass Liliaceae (lily) Daylilies, tulips, asparagus, aloe vera Poaceae (grass) Wheat, corn, rice, lawn grasses Asteraceae (composite) Daisies, sunflowers, lettuce, ragweed Brassicaceae (mustard) Broccoli, cauliflower, turnips, cabbage Fabaceae (legume) Beans, clovers, peas, peanuts, soybeans Rosaceae (rose) Roses, apples, peaches, pears, plums Solanaceae (nightshade) Potatoes, tomatoes, peppers, petunias Have students write down the key characteristics of each major group of plants discussed in this section. For each major group, have students provide one example. Then choose a student to read a description aloud, and allow fellow students to interrupt as soon as they recognize the group being described. Continue until all groups have been described at least twice. Quiz GENERAL 1. Mosses, liverworts, and horn- Section 2 Review Identify three key features of each of the four Critical Thinking Recognizing Patterns major groups of plants. How are spores and pollen grains adapted for their functions, and how do their numbers impact 13A their environment? 13B Classify each of the following plants into one of the phyla of living plants: pine trees, carnations, 8C sphagnum moss, and wood fern. Critical Thinking Evaluating Conclusions Why are angiosperms said to be the most 13A successful group of plants? TAKS Test Prep producing A spores. B cones. Ferns reproduce by 13B C flowers. D seeds. 515 Answers to Section Review 1. Nonvascular plants lack a vascular system, roots and true leaves; have a larger gametophyte generation, and produce spores. Seedless vascular plants have a vascular system, roots, and leaves; release spores; and have a larger sporophyte generation. Gymnosperms have a vascular system, roots, and leaves; produce spores; and have a larger sporophyte. Angiosperms have a vascular system, roots, leaves, and flowers; produce fruits and seeds; have a larger sporophyte. Bio 13B 2. Pine trees are gymnosperms; carnations are angiosperms; sphagnum moss is a nonvascular plant; and wood fern is a seedless vascular plant. TAKS 2 Bio 8C worts are examples of ________ plants. (nonvascular) 2. Gymnosperms reproduce by seeds that are produced in ________. (cones) 3. Plants that produce flowers with parts in groups of three are classified as ________. (monocots) Alternative Assessment Have students create a guide to the plants in the area. Students should create a booklet with the 3. Angiosperms are successful partly because they following sections: Nonvascular produce fruits that provide a mechanism for seed dispersal by wind, water, or animals. TAKS 3 Bio 13A Plants, Seedless Vascular Plants, Gymnosperms, Monocots, and 4. Spores and pollen grains have coats that are Dicots. Students should identify and resistant to harsh environmental conditions. record at least two species for each They may be transported by the wind or by section of their booklet. Bio 8C, 10C animals. The large amount of spores or pollen produced helps ensure reproduction and colonization of new environments. TAKS 3 Bio 13A 5. A. Correct. B. Incorrect. Gymnosperms reproduce by producing cones. C. Incorrect. Angiosperms reproduce by producing flowers. D. Incorrect. Ferns do not produce seeds Bio 13B Chapter 23 • Introduction to Plants 515 Section 3 Section 3 Plants in Our Lives Focus Overview Objectives Plants as Food Before beginning this section review with your students the objectives listed in the Student Edition. This section examines some of the many ways that humans use plants. Students will learn about food plants, including cereal grasses and other crops. This section will also discuss the many ways that trees can be used, including the chemicals and fibers obtained from trees and other plants. ● Identify foods that come from plants and their dietary importance. 13A TAKS 3 Humans depend on plants in many ways. For one thing, plants store the extra nutrients they make or absorb in their bodies. Thus, plant parts contain organic nutrients (carbohydrates, fats, and proteins) and minerals (calcium, magnesium, and iron). All types of plant parts—roots, stems, leaves, flowers, fruits, and seeds—are eaten as food. Bellringer Ask students to make a list of the different plant parts that can be eaten as food. (Students should list leaves, roots, stems, fruits, seeds, flowers, buds, bulbs, tubers, and shoots.) Ask students to name any other products that plants provide people. (Answers will vary, but may include wood, fibers for paper and textiles, medicines, chemicals, dyes, and oxygen.) Bio 10C ● Describe several ways that wood is used. 13A TAKS 3 ● Explain how plants are used to treat human ailments. 13A TAKS 3 ● Identify plants that are used to make paper and 13A TAKS 3 cloth. Key Terms vegetative part cereal grain Fruits and Vegetables The United States government identifies each of the foods that comes from a plant as an agricultural commodity. Each type of food is classified by a term—such as fruit or vegetable—that is registered in Washington, D.C. But, these terms have different meanings in botany. For example, to a botanist, a fruit is the part of a plant that contains seeds, and a vegetative part is any nonreproductive part of a plant. The foods that you think of as fruits—such as apples, bananas, and melons—are also fruits in the botanical sense. Vegetables, on the other hand, may be any botanical part of a plant, as you can see in Figure 19. Fruits and vegetables provide dietary fiber and are important sources of essential vitamins and minerals. Figure 19 Plant parts eaten as food The foods you eat come from different parts of plants. Fruits Flowers Shoots Motivate Leaves Discussion GENERAL Ask students to consider all of the ways plants contribute to our survival and way of life. Allow students to brainstorm and develop a list, then open the question for discussion. Ask students how much of their food, clothing, books, furniture, pencils, paper, oxygen, medicine, etc. comes from plants. Ask them to consider life without plants. What would people use instead of plants? (Answers will vary.) LS Interpersonal Storage structures Roots 516 REAL WORLD CONNECTION pp. 516–517 Student Edition TAKS Obj 2 Bio 6D TAKS Obj 2 Bio 8C TAKS Obj 3 Bio 13A TEKS Bio 6D, 8C, 13A Teacher Edition TAKS Obj 2 Bio 6D TEKS Bio 6D, 10C, 13B 516 Leafy vegetables are an important source of nutrition. Most greens can be eaten cooked or raw. Many varieties are rich in beta-carotene, vitamin C, folic acid, calcium, and iron. In general, darker leaves are more nutritious than lighter-colored leaves. Have students check references on nutrition (such as the USDA’s Composition of Foods) for vitamin, mineral, and fiber content of a variety of leafy green vegetables, as well as other fruits and vegetables and commonly eaten snack foods. Allow students to compare their results with each other. Chapter 23 • Introduction to Plants Chapter Resource File • Lesson Plan GENERAL • Directed Reading • Active Reading GENERAL • Datasheet for Quick Lab GENERAL Transparencies TT Bellringer Root Crops Potatoes are an important food staple in many parts of the world. Rich in calories and easy to grow, potatoes are an ideal crop for a small farm. Potatoes are classified as a root crop because they grow underground. But, potatoes are actually tubers, modified underground stems that store starch. Yams, an essential food crop in many tropical parts of the world, are also tubers. Sweet potatoes, carrots, radishes, turnips, beets, and cassava (kuh SAH vuh) are also important root crops. These vegetables are enlarged roots that store starch. Cassava, seen in Figure 20, is the staple food of more than 500 million people. Also known as manioc (MAN ee awk), cassava supplies more than one-third of the calories eaten in Africa. Legumes Many members of the pea family, which are called legumes, produce protein-rich seeds in long pods. For example, about 45 percent of a soybean, the most important legume grown for food, is protein. Soybeans are often cooked and pressed into cakes called tofu (TOH foo). Peas, peanuts, and the many different types of beans are the seeds of legumes. Alfalfa, which is fed to livestock, is another important legume. Like many legumes, alfalfa has nitrogen-fixing bacteria, which add nitrogen compounds to the soil, in its roots. Therefore, alfalfa is also grown to enrich the soil. Teach READING SKILL BUILDER Figure 20 Cassava. Cassava develops thick starch-filled roots up to 120 cm (4 ft) long. The roots are eaten like potatoes. Tapioca, shown above in the bowl, is made from cassava. Distinguishing Fruits and Vegetables 6D TAKS 2 Differentiating Fruits and Vegetables You can find out if a plant product is a fruit by cutting it open and examining its internal structure. TAKS 2 Bio 6D; Bio 10C, 13B Materials Skills Acquired Analyzing data, analyzing results, drawing conclusions apple, banana, green bean, potato, squash, tomato, plastic knife Procedure 1. Look at several familiar fruits and vegetables. Classify each one as either a fruit or a vegetable in the familiar sense. 3. Look at the fruits and vegetables again. Classify each by its botanical function—either a fruit or a vegetative part. 2. Critical Thinking Analyzing Data Which fruits and vegetables did you classify differently? 2. Analysis 3. Critical Thinking Analyzing Results Defend the classifications you made for item 2. CAUTION: Sharp objects can cause injury. Handle knives carefully. Use a plastic knife to cut open each fruit and vegetable. Anticipation Guide Before students begin this section, write the following statements on the board or overhead projector: 1. Wood is the most valuable resource that people get from plants. 2. Most of the food that people eat comes from fruits. 3. Plants produce many chemicals that are useful as medicines, but none that are poisonous. Ask students to decide whether they agree or disagree with each statement. Ask volunteers to share the reasons for their opinions. Have students read the chapter to see if their opinions are confirmed or changed. 1. Compare the familiar and botanical classifications you gave each fruit and vegetable. 4. Critical Thinking Drawing Conclusions Based on your data, when is a vegetable a fruit? 517 Cultural Awareness Cassava The staple crop of Brazil and many other tropical and subtropical countries is a perennial shrub root called cassava, or manioc. It is asexually propagated from tuberous roots. These starchy roots contain compounds that form cyanide, which must be removed through processing before eating. The roots are usually ground into flour and used in cooking. Processing methods are complex, labor intensive, and pose a risk of cyanide poisoning to processors. In Brazil, toasted cassava meal, or “farofa,” is served at most meals. Cassava is also used to make tapioca and beer in some cultures. There are bitter and sweet varieties of cassava, with varying levels of toxicity. Worldwide, cassava helps to feed more than 500 million people. Teacher’s Notes Point out that some true fruits might not have obvious seeds. Commercially produced bananas are sterile triploids (3n). The fruit is large but the seeds are difficult to see and not viable. Answers to Analysis 1. Apples and bananas are true fruits. Green beans, squash, and tomatoes are true fruits that most people would identify as vegetables. Potatoes are vegetative structures that are familiarly called vegetables. 2. Students will probably need to reclassify green beans, squashes, and tomatoes as fruits. 3. True fruits contain seeds, many of the “vegetables” in this lab contain seeds which makes them true fruits. 4. A “vegetable” is a fruit if it is produced from a flower, contains parts of the flower (ovary), and contains seeds. Chapter 23 • Introduction to Plants 517 Cereals Most of the foods that people eat come directly or indirectly from the fruits of cereals. Cereals are grasses that are grown as food for humans and livestock. Cereal grasses produce large numbers of a type of edible, dry fruit called a grain . A grain contains a single seed with a large supply of endosperm. Each grain develops from a flower. The flowers of cereal grasses form in tightly packed clusters of many individual flowers. A grain is covered by a dry, papery husk called the bran, which includes the wall of the ovary and the seed coat. Cereal grains are rich in carbohydrates and also contain protein, vitamins, and dietary fiber. More than 70 percent of the world’s cultivated farmland is used for growing cereal grains. In fact, more than half of the calories that humans consume come from just three cereal grasses: wheat, corn, and rice. Teach, continued continued Teaching Tip GENERAL Small Selection of Crops Tell students that approximately 80,000 species of plant species produce edible parts, but only 50 of these are cultivated as major food sources. Seven of these species—rice, wheat, corn, barley, sorghum, potatoes, and cassava— make up 75 percent of the food consumed around the world. SKILL BUILDER Wheat GENERAL Math Skills Tell students that of the 560 million metric tons of wheat produced around the world each year, 20 percent is used to feed livestock, and 80 percent feeds humans directly. Of the 520 million metric tons of rice produced, almost 100 percent feeds humans. Finally, of the 530 million metric tons of corn produced, 65 percent is used to feed livestock, the rest going directly to humans. Have students calculate the amount of each crop eaten by humans (in metric tons), then prepare bar graphs to display this information. Have students describe this information in writing, and rank each crop in terms of the amount eaten by humans. (Rice is the most important, at nearly 520 million metric tons; wheat is second, at 448; and corn is third, at 185.5 million metric tons.) LS Logical TAKS 1 Bio/IPC 2C, 2D Figure 21 Wheat. Modern bread wheat is a hybrid of three wild species. The ripenend heads of bread wheat turn golden brown. For more than one-third of the world’s population, wheat, seen in Figure 21, is the primary source of food. The endosperm of wheat grains, which is high in carbohydrates, is commonly ground into white flour and used to make breads and pasta. Vitamin-rich wheat germ consists of the embryos of wheat grains. Whole-wheat flour consists of the endosperm plus the germ and bran layers. Wheat grains are not always ground into flour. In the Middle East, wheat grains are often boiled or soaked, dried, and then pounded until they crack. The cracked grains, called bulgur (BUL guhr), are used in dishes such as tabbouleh (tuh BOO lee) and pilaf (pih LAHF). Most wheat is grown in temperate regions that have fertile soil and moderate rainfall. One of the world’s best wheat-growing areas is the Great Plains region of the United States and Canada—a temperate grassland biome. Corn Figure 22 Corn. Each ear of corn developed from a flower spike that consisted of more than 500 flowers. Corn, seen in Figure 22, is the most widely cultivated crop in the United States. American colonists of the 1600s and 1700s first learned how to grow corn from Native Americans. In the southeastern United States, corn was more widely grown than wheat, which does not grow as well in hot climates. Thus, foods that are made from corn—corn bread, corn pone, hominy, and grits—are a traditional component of the southeastern American diet. Corn is also one of the world’s chief foods for farm animals. About 70 percent of the corn crop harvested in the United States is consumed by livestock. Other uses for corn include the production of corn syrup, margarine, corn oil, cornstarch, and fuel-grade ethanol. Most of the corn grown in the United States today comes from a region known as the Corn Belt, which includes Iowa, Nebraska, Minnesota, Illinois, and Indiana. 518 did you know? pp. 518–519 Student Edition TAKS Obj 2 Bio 6D TAKS Obj 3 Bio 7B TAKS Obj 3 Bio 13A TEKS Bio 6D, 7B, 8C, 11C, 13A Teacher Edition TAKS Obj 1 Bio/IPC 2C, 2D TEKS Bio/IPC 2C, 2D, 3C TEKS Bio 3F, 11C 518 Wheat Strains Help Mexico In 1944 new strains of wheat helped end food shortages in Mexico. Norman Borlaug, who helped launch the Green Revolution, was awarded the Nobel Prize in 1970 for developing new strains of wheat in Mexico. His research on wheat began in 1944. Within 20 years, Mexico had enough wheat not only to feed its own people but also to export to other countries. India and Pakistan experienced similar successes. Borlaug’s highyielding strains were produced from crosses with a dwarf variety. Bio/IPC 3C, Bio 3F Chapter 23 • Introduction to Plants Planner CD-ROM • Reading Organizers • Reading Strategies • Portfolio Project Plant Research Project GENERAL Rice For more than half of the people in the world, rice is the main part of every meal. Although it is low in protein, rice is an excellent source of energyrich carbohydrates. While brown rice still has its vitamin-rich bran layers, white rice has been processed to remove the bran layers. This processing helps to prevent spoilage in stored rice. In societies where people eat mainly rice, vitamin-rich sauces such as soy sauce are often added to white rice to make meals more nutritious. The white rice you buy at a grocery store is enriched with added vitamins. Rice is often added to processed foods such as breakfast cereal, soup, baby food, and flour. In the United States, rice is grown in central California, in the Southeast, and along the Gulf Coast in fields such as the one shown in Figure 23. Group Activity Figure 23 Texas rice field. Rice plants are grown in standing water. Local Plant Processing Have students work in groups of three or four. Ask them to prepare a report describing 10 plant-based products made within a 150km radius of the school. Some possible products include cereals and other crops, food processing, forestry, furniture, wood products, nurseries and greenhouses; textiles, plant-based cosmetics, plant-based medicines and supplements, and paper production or paper recycling. As part of the project, have students create a map with the school at its center and the various plant-based industries located on the map. Co-op Learning TAKS 1 Bio/IPC 2C, 2D Vegetarian Diets GENERAL M any people are vegetarian; they eat only foods from plants. Like any diet, vegetarian diets must satisfy the body’s nutritional needs to be healthy. Two important considerations in eating a healthy vegetarian diet are the essential amino acids and vitamins B-12 and D. Getting the Essential Amino Acids Essential amino acids is the term for those amino acids that the human body cannot make. Most plant proteins contain all of the essential amino acids, but in different relative amounts. For example, cereal proteins tend to be low in lysine and high in methionine; the opposite is true for the proteins in beans. Traditionally, cereals and beans are eaten together to obtain enough of the essential amino acids. However, vegetarians can get the essential amino acids they need even if they do not eat a variety of plant foods, as long as they eat enough protein. For example, if you eat enough rice to satisfy your daily protein requirement, you will get more than twice your daily requirement for lysine. The recommended daily requirement for protein is 44 g for a 55 kg (121 lb) woman and 56 g for a 70 kg (154 lb) man. Legumes, grains, nuts, broccoli, and potatoes are good sources of protein. Vitamins B-12 and D A vegetarian diet generally can provide enough of all but two vitamins, vitamin B-12 and vitamin D. To get enough vitamin B-12, Vegetarian Diets vegetarians can eat fortified foods, add eggs or dairy products to their diet, or take vitamin B-12 supplements. Vitamin D is made in the skin when it is exposed to sunlight. Vegetarians may need to take vitamin D supplements if their exposure to sunlight is limited. www.scilinks.org Topic: Vegetarian Diets Keyword: HX4184 519 Cultural Awareness Rice and Culture Rice plays an important part in the customs and economies of many cultures where it is a major food source. For example, Japanese place a shiminawa, or rice-straw rope, over an entrance to ward off evil. The largest rope in the world is a shiminawa that hangs over the entrance to the Izumo Shinto Shrine and weighs 6 metric tons. Rice is the symbol of the goddess of wealth and prosperity and is often worshiped as a goddess by the Hindu. The act of pouring rice over someone’s head signifies prosperity and happiness. Students may find this amusing. Remind them of the familiar western custom of throwing rice at a wedding. 11C Teaching Strategies Bring in cookbooks or pictures of vegetarian meals that provide good quality and quantity of essential amino acids and are good sources of vitamins B-12 and D. Some examples are bean and cheese tacos on wheat or corn tortillas and tofu with rice and green vegetables. Point out that in many parts of the world, the majority of calories come from combinations of grains and legumes. (South America: corn and beans; Asia: rice and soybeans) Discussion After students have read the feature, ask students: Which essential amino acids are commonly abundant in meat products but low in cereal grains and legumes? (lysine, is low in cereal grains; methionine, is low in legumes) Why is a varied diet that includes animal products, such as milk, eggs, and cheese, important for vegetarians? (A varied diet is more likely to provide all the essential amino acids and vitamins, some of which are hard to obtain from non-animal products.) Chapter 23 • Introduction to Plants 519 Nonfood Uses of Plants Plants are used by people for many purposes other than food. For example, rubber was first made from latex, the milky white sap of tropical trees of the genus Hevea. Latex is extracted from rubber trees by the method seen in Figure 24. Guayule (gwah YOO lee), a member of the sunflower family that is native to the southwestern United States, is another source of natural rubber. (Most of today’s rubber, however, is synthesized from petroleum, a nonrenewable resource.) The most important nonfood products obtained from plants are wood and fibers. Teach, continued continued Demonstration GENERAL Bring the following to class: some biodegradable packing pellets, some Styrofoam peanut pellets, 2 beakers of water, and iodine in a dropper bottle. To show the advantages of biodegradable products, drop a few of the biodegradable packing pellets into a beaker of water. Stir until dissolved. Add several drops of iodine to the beaker, and note color change. Ask students to identify the composition of the pellets. (Purple indicates starch, from corn in this case.) Repeat the procedure with the Styrofoam peanuts. Point out that both products are reusable, but only the cornstarch-based pellets will easily biodegrade. Bio/IPC 1B Activity GENERAL Paper Types Have students make wet-mount slides of various types of paper and then observe the slides under a microscope. Staining the paper with methylene blue will make the fibers more visible. Have students draw what they see and relate the fibers to the characteristics of the papers. (Students should notice that longer fibers are present in higher quality papers, while short fibers are present in soft papers such as tissue.) LS Visual Bio 10C Teaching Tip Figure 24 Latex. The milky sap of certain plants is called latex. This man is collecting latex from a rubber tree in Java, Indonesia. Wood After food, wood is the single most valuable resource obtained from plants. Countless products, such as those shown in Figure 25, are made from wood. The wood from trees that have been cut down and sawed into boards is called lumber. Nearly 75 percent of the lumber cut in the United States is used for building construction. The rest is used to make products that contain wood, or it is ground and moistened to make wood pulp. Wood pulp is made into paper, rayon, and many other products. Finally, for more than a quarter of the world’s people, wood is still the main source of fuel for heating and cooking. Figure 25 Items made with wood Furniture, buildings, boats, cabinets, and violins are made from wood. GENERAL Products That Come From Trees Have students make a Graphic Organizer similar to the one at the bottom of this page to illustrate the importance of trees. Ask them to use the vocabulary words applicable for this section, together with any other words that they wish to include. TAKS 3 Bio 13A 520 Graphic Organizer Use this graphic organizer with Teaching Tip on this page. latex Trees are used as pp. 520–521 Student Edition TAKS Obj 3 Bio 13A TEKS Bio 13A TEKS Bio/IPC 3C Teacher Edition TAKS Obj 3 Bio 13A TEKS Bio 13A TEKS Bio/IPC 1B, 3C 520 produce which is used to make taxol medicines such as aspirin produce fuel buildings other products Chapter 23 • Introduction to Plants rubber which is used to make lumber which is ground into wood pulp which is used to make paper rayon Figure 26 Sources of medicines These two common garden plants are the sources of important medicines. Teach, continued continued READING SKILL BUILDER Foxglove, the source of a drug used to treat cardiac disorders Rosy periwinkle, the original source of two cancer-fighting drugs Reading Organizer Have students keep a list of plants and their uses as they read this section. When they have finished reading, have them make a table of the items in their list. Medicines MEDICINE People have always used substances obtained from plants to treat a variety of ailments. By studying the plants traditionally used to treat human ailments, researchers have developed many “modern” medicines. For example, solutions made by soaking the bark of willow trees, Salix, were a traditional cure for aches and pains. The pain-relieving chemical found in willows is called salicin (SAL uh sihn). Acetylsalicylic (uh SEET l sal uh SIHL ihk) acid, a derivative of salicin, was first sold in 1899 under the name “aspirin.” Today, aspirin is the most widely used pain-relieving drug in the world. Two familiar garden plants, seen in Figure 26, are important sources of life-saving medicines. The extremely poisonous leaves of the foxglove, Digitalis purpurea, yield digitalis (dihj ih TAL ihs), a drug that is used to stabilize irregular heartbeats and to treat cardiac disorders. The rosy periwinkle, Catharanthus roseus, is the original source of two cancer-treatment drugs—vinblastine (vihn BLAS teen) and vincristine (vihn KRIHS teen). Vinblastine is often used to treat Hodgkin’s disease, a type of cancer that affects the lymph nodes. Vincristine is used to treat childhood leukemia and other types of cancer. Table 2 contains other examples of medicines that originally derived from plants. CONNECTION The potato plant is a member of the nightshade family (Solanaceae). Many plants in this family produce alkaloids that are poisonous to people and animals. Some examples are tobacco, which produces the alkaloid nicotine; jimson weed and datura, which produce the alkaloids atropine and scopolamine, and belladonna, which also produces atropine. Atropine and scopolamine are used to treat muscle spasms. The belladonna’s name (“beautiful woman”) refers to the old practice of placing drops of the plant extract into women’s eyes, which resulted in dilated pupils. Potato plants are normally not poisonous, but if the tubers are exposed to light, they may turn green. These green portions contain alkaloids that are harmful in large quantities. Table 2 Some Drugs Originally Derived from Plants Name Source www.scilinks.org Topic: Medicines from Plants Keyword: HX4119 Action Caffeine Tea leaves Acts as a stimulant Codeine Poppy fruits Relieves pain Cortisone Yam tubers Relieves symptoms of allergies Ephedrine Ephedra stems Acts as a decongestant Taxol Yew tree bark Reduces the size of cancerous tumors 521 did you know? Biotech Plants May Help Fight Cancer Genetic engineering offers hope of introducing the anticancer proteins found in foods, such as broccoli, into other fruits and vegetables. People would have a wider variety of plant foods to choose from to obtain these proteins. Those who do not like to eat broccoli and related plants could get these proteins from other sources. Bio/IPC 3C Trends in Textile Fabrication Friendlier Rayon Rayon is a synthetic fabric made from chemically altered cellulose fibers, usually obtained from wood. Clothing, curtains, upholstery and industrial products are made from rayon. New research is aimed at making rayon using a more environmentally friendly process. Transparencies TT Some Drugs Originally Derived from Plants Chapter 23 • Introduction to Plants 521 Figure 27 Cotton Cotton is the plant fiber that is most widely used to make cloth. Close Reteaching Have students work in groups of three or four. Have each group answer the following questions with as many examples as they can think of: What are the most important cereal grains? (wheat, rice, and corn) What are some other plants used as food sources? (lentils, soybeans, sugar cane, cassava, etc.) What are some of the important products of the timber industry? (lumber, paper, fuel, turpentine) what are some medicines derived from plants? (taxol, codeine, digitalis, ephedrine, etc.) When groups are finished, have students share their answers. Quiz GENERAL 1. List six plant parts that can be used as food. (Roots, stems, flowers, fruits, seeds, and leaves are all used as food.) 2. True or false: scientists have identified all of the possible medicines that can be made from plants. (False. Not all plants have been discovered, and there are chemicals produced by plants that have never been tested.) Alternative Assessment Cotton bolls that have split open, revealing cotton fibers Indian woman spinning cotton into thread that will be woven into cloth Fibers Reviewing Information Prepare flashcards for each of the Key Terms in this chapter. On each card, write the term on one side and its definition on the other side. Use the cards to review meanings of the Key Terms. If you were to look at this sheet of paper very closely through a magnifying glass, you would see that it is made of many interlocking fibers. These fibers are strands of cellulose, which is a component of the cell walls of plants. In plants, fibers help provide support for the plant body. The strength and flexibility of plant fibers make them ideal materials for making paper, cloth, and rope. Most of the fibers used to make paper come from wood. Paper-making fibers are also obtained from many other plants, including cotton, flax, rice, bamboo, and papyrus (puh PIE ruhs). For centuries, people have made clothing with cloth made of cotton, the world’s most important plant fiber. As Figure 27 shows, white fibers fill up the inside of a cotton boll (bohl), the fruit of the cotton plant. Cotton thread is spun from the fine white fibers, which grow on cotton seeds. The stems of flax yield softer, more durable fibers that are used to make linen. More than 30 percent of the world’s clothing is now made of synthetic fibers, but natural plant fibers are still prized for their durability and comfort. Sturdy fibers of hemp and sisal (SIE suhl) plants are used to make rope. Section 3 Review Describe several ways in which wood is used. GENERAL Assign students to cooperative groups to prepare a lunch menu that consists only of plant-derived foods, utensils, and furniture. Students should take care to design a fully nutritional meal. Provide a library cart of reserved books selected for your class for the project. Co-op Learning Bio 11C and state how each is used. 13A Name three types of plants that provide fiber used in clothing. 13A Critical Thinking Predicting Results Name the three most important cereal grains and pre12D dict the results if one of them ceased to exist. 522 TAKS Test Prep Which plant has nitrogen-fixing bacteria in its roots? A potato B wheat C alfalfa D corn 13A 522 Answers to Section Review TAKS 3 Bio 13A pp. 522–523 Critical Thinking Evaluating Viewpoints Justify the viewpoint that wood is the most 13A important nonfood plant product. List five medicines that are derived from plants, 1. Wood is used for fuel, lumber, furniture, tools and utensils, paper, rayon and turpentine. Student Edition TAKS Obj 3 Bio 13A TEKS Bio 12D, 13A Teacher Edition TAKS Obj 3 Bio 13A TEKS Bio 11C, 12D 13A 2. Aspirin is used as a pain reliever and antiinflammatory; digitalis is used to treat heart disorders; vinblastine is used to treat cancer; codeine is used as a pain reliever; cortisone is used to treat allergies; ephedrine is used as a decongestant; and taxol is used to treat cancer. TAKS 3 Bio 13A 3. cotton, flax, hemp TAKS 3 Bio 13A 4. Wheat, rice, and corn. Students should recognize that alternative food sources would need to be Chapter 23 • Introduction to Plants quickly utilized or massive starvation could result. Bio 12D 5. Answers will vary, but students should recognize that wood is used in many ways. TAKS 3 Bio 13A 6. A. Incorrect. Potatoes have underground, starchy tubers, but do not contain nitrogen-fixing bacteria. B. Incorrect. Wheat needs nitrogen for healthy growth, but it does not contain nitrogen-fixing bacteria. C. Correct. Alfalfa and members of the pea family are some of the plants that contain bacteria in root nodules that fix nitrogen into a form usable by plants. D. Incorrect. Corn, like all plants, needs nitrogen for healthy growth, but corn roots do not contain nitrogen-fixing bacteria. TAKS 3 Bio 13A Study CHAPTER HIGHLIGHTS ZONE Key Concepts ● To survive on land, plants must absorb mineral nutrients, prevent their bodies from drying out, and reproduce without water to transmit male gametes. ● Vascular plants have a system of well-developed tissues that transport water within a plant. The nonvascular plants lack a vascular system.• The Science TAKS Prep Appendix in ● Seeds protect andthis nourish a plant’s embryo,bioldisperse book provides integrated andthe IPC growth TAKS practice the offspring, andogy delay of the embryo until conditions are favorable. FlowersTAKS make reproduction more • The Holt Science Practice efficient by promoting pollination. Workbook provides a review of ● biology, chemistry, physics The sporophytes of vascular plantsand have a vascular system. concepts on the grades 10 and an underTheir bodies consist of an tested aboveground shoot and 11 science TAKS. ground root. GENERAL Have students use the information in Chapter 23 to design a procedure for a question-and-answer game. Students may choose to model their game after a television game show or a trivia-type board game. Encourage students to write questions that vary in difficulty. Section 1 1 Adaptations of Plants cuticle (502) stoma (502) guard cell (503) vascular system (504) nonvascular plant (504) vascular plant (504) seed (504) embryo (504) seed plant (504) flower (505) phloem (507) xylem (507) shoot (507) root (507) meristem (507) Section 2 2 Kinds of Plants ● Alternative Assessment Key Terms Chapter Resource File Nonvascular plants are small and lack vascular tissue. Mosses, liverworts, and hornworts are nonvascular plants. GENERAL • Science Skills Worksheet ● Seedless vascular plants produce spores with thickened • Critical Thinking Worksheet walls that prevent them from drying out. Ferns, club mosses, GENERAL vascular plants. Test Prep Pretest horsetails, and •whisk ferns are seedless ● Chapter Test GENERAL Gymnosperms •are seed plants that produce cones. Conifers, cycads, ginkgoes, and gnetophytes are gymnosperms. ● Angiosperms are seed plants that produce flowers and fruits. The angiosperms are classified as either monocots or dicots. rhizoid (508) rhizome (510) frond (511) cone (511) gymnosperm (512) angiosperm (514) fruit (514) endosperm (514) monocot (515) dicot (515) Section 3 3 Plants In Our Lives vegetative part (516) cereal (518) grain (518) ● All types of plant parts—roots, stems, leaves, flowers, fruits, and seeds—provide food for humans. Rice, corn, and wheat are cereal grasses and are our most important sources of food. ● Wood is a source of wood pulp used for making paper, lumber used for building materials, and fuel. ● Many important medicines are currently made from plants or were originally derived from plants. ● Plant fibers are used to make paper, cloth, and rope. The most important sources of plant fibers are wood and cotton. 523 Plants Answer to Concept Map The following is one possible answer to Performance Zone item 15. may be vascular plants nonvascular plants have include lack vascular tissues angiosperms gymnosperms have have flowers seeds include dicots monocots include liverworts mosses include ferns gnetophytes cycads ginkgo lack conifers have seeds cones Chapter 23 • Introduction to Plants 523 Performance ZONE CHAPTER 23 ANSWERS Using Key Terms 1. b TAKS 3 Bio 13A 2. a Bio 13B 3. b TAKS 2 Bio 6D 4. d TAKS 2 Bio 6D; TAKS 3 Bio 13A 5. a. Xylem is water-transporting tissue; phloem is a tissue that transports sugars and other organic molecules. b. A shoot is the above ground part of a plant; a root is the below ground part of a plant. c. A rhizoid is a root-like structure that anchors a plant; a rhizome is an underground stem. d. A seed contains an embryo, a seed coat, and stored food; a fruit contains part of the flower (ovary) and seeds. Understanding Key Ideas 6. a TAKS 3 Bio 13A 7. c Bio 10C, 13B 8. d Bio 13B 9. a Bio 13B 10. c 11. b 12. The seeds would likely be dispersed by becoming attached to the fur of a mammal and being transported as the mammal moves around. Bio 10A, 13B 13. Answers may vary. Vegetarian diets should contain grains and legumes, as well as sources of vitamins B-12 and D such as dairy products, fortified foods, and vitamin supplements. Bio 11C 14. Meiosis involves two divisions of the nucleus, which reduces the number of chromosomes in a cell and produces four haploid cells; in plants the cells that result directly from meiotic division are called spores. Bio 6E Review and Assess TAKS 1 Bio/IPC 2A, 2D TAKS 2 Bio 6D TAKS 3 Bio 7B, 13A TEKS Bio 3D, 3E, 6D, 6E, 7B, 10C, 11C, 13A, 13B; Bio/IPC 2A, 2D 524 CHAPTER REVIEW Using Key Terms 1. What structure made it possible for plants to prevent water loss and to spread 13A on land? a. mycorrhizae c. pollen b. cuticle d. seed 11. Drugs derived from the rosy periwinkle are used in the treatment of 13A a. heart disease. c. allergies. b. leukemia. d. headaches. 13B c. zygospore. d. epiphyte. 3. Which of the following are not seedless vascular plants? a. horsetails b. gymnosperms 12. Look at the cocklebur in the photograph below. It is a fruit that contains the seeds of a cocklebur plant. Suggest how this plant’s 10A 13B seeds might be dispersed. 6D c. ferns d. club mosses 4. Which of the following is not a source of fibers for both paper and cloth? a. flax c. wood b. cotton d. sisal 6D 13A 5. For each pair of terms, explain the differ- ences in their meanings. a. xylem, phloem c. rhizoid, rhizome b. shoot, root d. seed, fruit Understanding Key Ideas 6. Seeds helped plants adapt to life on land by 10C 13A a. providing nourishment for embryos. b. protecting embryos from air pollution. c. sprouting during unfavorable weather. d. limiting the dispersal of plant offspring. 7. Which of the following is not a characteristic 10C 13B of vascular plants? a. xylem and phloem b. stems and leaves c. a dominant gametophyte d. a diploid sporophyte 8. Unlike angiosperms, gymnosperms 13B a. are pollinated by wind. b. do not have seeds. c. have a diploid sporophyte generation. d. do not bear fruit. 13. A friend is concerned that your vegetarian diet is not healthy. Make a list of the measures you would take to ensure that your diet will provide you with all the nutrients you need. 11C 14. How does meiosis result in the production of haploid spores? (Hint: See Chapter 7, Section 1.) 6E 15. Concept Mapping Make a concept map that shows how plants are classified. Include the following terms in your map: vascular plants, nonvascular plants, ferns, angiosperms, gymnosperms, mosses, cones, vascular tissue, seeds, and flowers. 3E 524 15. One Possible answer to the concept map is found at the bottom of the Study Zone page. Bio 3E Critical Thinking 16. The sporophytes are large and have many leaves that can intercept light from the sun. A vascular system enables the sporophytes to grow very large by distributing water and nutrients efficiently. Their reproductive cells (eggs and sperm) are produce near the tops of the sporophyte, where they can readily be dispersed by wind or animals. TAKS 3 Bio 7B Chapter 23 • Introduction to Plants 13B 10. The most important sources of food are a. legumes. c. cereal grains. b. root crops. d. vegetables. 2. Plant life cycles include a diploid individual that is called a(n) a. sporophyte. b. gametophyte. 9. Which of the following are not dicots? a. grass family c. mustard family b. rose family d. legume family Assignment Guide Section 1 2 3 Questions 1–2, 5a–c, 6, 14, 16–17 3, 5d, 7–9, 12, 15 4, 10–11, 13, 18–22 13A