This Document Contains Chapters 25 to 27 CHAPTER 25: FUNGI WHERE DOES IT ALL FIT IN? Chapter 25 is consistent with type of coverage provided in Chapters 23 and 24, and highlights the fungal diversity. Students should be encouraged to recall the principles of eukaryotic cell structure and evolution associated with the particular features of fungal cells. The information in chapter 25 does not stand alone. Students should know that fungi and other organisms are interrelated and originated from a common ancestor of all living creatures on Earth. SYNOPSIS • • Even though fungi have been traditionally classified with plants, the two kingdoms have little in common. In fact, molecular data show that fungi are more closely related to animals than plants. But, in comparing plants versus fungi, we see that plants are photosynthetic, while fungi are heterotrophs obtaining nutrients by secreting enzymes into their substrate and absorbing the digested materials. Plants are composed of several types of cells organized into tissues and organs, while fungi are basically filamentous, composed of hyphae packed into complex structures like mushrooms. Plant cell walls contain cellulose, fungi cell walls are mostly polysaccharides impregnated with chitin. Both plants and fungi reproduce sexually and asexually. Plants and fungi are also similar in their immobility and their linear reproductive structures. Fungi are also different from either plants or animals in their cell division. The nuclear envelope remains intact during mitosis, the spindle apparatus forms within the nucleus and is regulated by spindle plaques. Centrioles are found in animals, but not in fungi or plants. Fungi are similar to prokaryotes in their ecological and commercial value as decomposers and in food production. They are among the few organisms that are able to decompose lignin, a major constituent of wood. Fungi made it possible for plants to colonize on land through mutualistic associations between fungal organisms and plant roots. • Fungi are composed of filamentous hyphae, which are slender filaments; a mass of hyphae is called the mycelium. Hyphae can be either non-septate where there is no separation between individual cells except where reproductive cells form; or, hyphae are septate, but the barrier between vegetative cells can be partially complete allowing cytoplasm to flow freely from one cell to the next or the septae are complete where reproductive cells are formed. All fungal nuclei are haploid, except those of the zygote. Homokaryotic hyphae contain genetically similar nuclei while heterokaryotic hyphae are derived from two genetically distinct individuals. In monokaryotic hyphae each cellular compartment possesses only one haploid nucleus while dikaryotic hyphae possess two genetically distinct haploid nuclei per cellular compartment. Spores are the most common means of reproduction and are formed by sexual or asexual processes. • The four major groups of fungi are: Chytridiomycota, Zygomycota, Basidiomycota, and Ascomycota. Chytridiomycota are aquatic, flagellated fungi that produce motile, flagellated zoospores and play a symbiotic role in the ecosystem. Phylum Zygomycota contain about 1050 zygomycetes species. In the Zygomycota, hyphae fuse and produce a hard¬-walled zygote that undergoes meiosis at germination. The group is named after a feature of the sexual phase of the life cycle called a zygosporangium. Zygomycota contains decomposers, parasitic forms and human pathogens, with the most common species, Rhizopus, the bread mold. The group Basidiomycota includes the more familiar fungi including the mushrooms, toadstools, puffballs, jelly fungi and shelf fungi as well as many plant pathogens, rusts and smuts. This group is named for their characteristic reproductive structure, the basidium. In both the Ascomycota and the Basidiomycota, reproductive cells are produced from dikaryotic hyphae with meiosis immediately following syngamy. Basidiomycetes produce four haploid spores on the tip of a club-shaped basidium. Phylum Ascomycota contain about 75% of all known fungi, including: bread yeasts, common molds, morels and truffles, chestnut blight fungi and Dutch elm disease causing fungi, and the penicillin producing ascomycetes. Ascomycetes produce eight haploid spores within a sac-like ascus. Asexual reproduction is common in Ascomycota, and also occurs in the Zygomycota, but is rare in the Basidiomycota. Yeasts are important in the production of bread, beer, wine, and in genetic research. • Fungi form important symbiotic associations with plants and animals including: lichens, mycorrhizae, endophytes, mutualistic animal symbiosis and fungal parasites and pathogens symbioses. Lichens are a mutualistic association between a fungus and a photosynthesizer. They generally inhabit cold, dry inhospitable environments and help prepare the habitat for other organisms. They are extremely sensitive to pollution. Mycorrhizae form mutualistic associations between the fungi and plant roots. There are two types of mycorrhizae: (1) arbuscular mycorrhizae, the most common, in which the fungal hyphae penetrate the outer cells of the plant root and, (2) ectomycorrhizae where the hyphae surround but do not penetrate the cell walls of the roots. They likely increase crop yields with less input of energy, provide better growth in poor soils, and may have added plants in their initial invasion of the land. Arbuscular mycorrhizae helped early plants succeed on poor soils and are being studied for their potential of increasing crop yields. Ectomycorrhizae are symbionts of temperate tree and shrub roots. Endophytes are plants that have fungi living inside them in intercellular spaces and may provide protection against herbivores by producing toxins and/or other deterrents. A mutualistic fungal-animal symbiosis has been identified in ruminant animals that host fungal organisms in their gut. Another example includes the leaf cutter ants that grow fungi in underground gardens. Yet, another symbioses relation exists between fungal parasites and pathogens. One example would be a parasitic fungal-animal symbiosis, such as that found in the disease thrush caused by Candida species. Still other parasitic/pathogen relationships exist in plants as fungal pathogens of plants. In addition, animals can be ill from consuming the plants. An example of this is toxic compounds produced by some Aspergillus species growing on corn, peanuts and cotton seed. When consumed by people, damage can occur to the kidneys and the nervous system. • LEARNING OUTCOMES 25.1 Fungi Are Unlike Any Other Multicellular Organism 1. Compare the body of a fungus with that of a plant. 2. Compare mitosis in fungi and plants. 3. Explain why the body design of fungi suits their form of heterotrophy. 25.2 Fungi Are Taxonomically Diverse 1. List the major phyla of fungi. 25.3 Microsporidia Are Unicellular Parasites 1. Describe the characteristics of microsporidia. 25.4 Chytrids Have Flagellated Zoospores 1. Explain the meaning of “chytrid”. 25.5 Zygomycota Produce Zygotes 1. Describe the defining feature of the zygomycetes. 2. Describe the structure and functioning of sporangiosphores. 25.6 Glomeromycota Are Asexual Plant Symbionts 1. Describe reproduction among the glomeromycota, 2. Explain the advantage of zygospore formation. 25.7 Basidiomycota Are the Mushroom Fungi 1. Distinguish between primary and secondary mycelium in a basidiomycete. 25.8 Asomycota Are the Most Diverse Phyla of Fungi 1. Compare the ascomycetes to the basidiomycetes. 2. Distinguish between conidia and basidospores. 25.9 Fungi Have an Enormous Ecological Impact 1. Identify a trait that contributes to the value of fungi in symbiotic relationships. 2. Describe the living components of a lichen. 3. Contrast mycorrhizae and lichens. 4. Contrast mutualistic symbioses in animals with those in plants. 25.10 Fungi Are Important Plant and Animal Pathogens 1. Explain why treating fungal infections in animals is particularly difficult. COMMON STUDENT MISCONCEPTIONS There is ample evidence in the educational literature that student misconceptions of information will inhibit the learning of concepts related to the misinformation. The following concepts covered in Chapter 25 are commonly the subject of student misconceptions. This information on “bioliteracy” was collected from faculty and the science education literature. • Students do not believe that fungi contain organelles • Students believe that fungi are a type of plant • Students believe that fungi are single celled • Students do not know that fungi carry out sexual reproduction • Students are unaware that fungi produce eggs • Students do not understand that fungi can produce zygotes which they think are only found in animals • Students do not classify yeast as fungi • Students are unaware that fungi grow in aquatic environments • Students believe that all fungi produce mushrooms • Students believe that the body of the fungus are the above-ground reproductive structures • Students are unaware of fungal diseases • Student believe that fungi only consume decaying matter • Students confuse the function of hyphae with roots • Students do not realize that fungi undergo meiosis • Students do not realize that hyphae grow by mitosis • Students believe that fungi only grow in the dark • Students believe that lichens are self-sufficient and have no environmental needs INSTRUCTIONAL STRATEGY PRESENTATION ASSISTANCE It is important for the students to understand the uniqueness of fungal genetics and reproduction and the terminology associated with them. Fungi are unique in that even the largest mushrooms are no more than a mass of filaments. They do not exhibit extensive tissue differentiation or specific organs and organ systems as do plants and animals. For the most part, the only specialized cells in fungi are those associated with sexual or asexual reproductive processes. Nearly all fungi fruit above ground so that their spores are readily dispersed by the wind and rain. Truffles are an exception in that they fruit underground. They also produce chemicals similar to certain animal pheromones. Animals, especially pigs, are attracted to the odor of mature truffles, dig them up, and distribute the spores. Discuss particularly common mushrooms found in your area. Stress the importance of knowing the identity of a mushroom before eating it. Some are hallucinogenic; others cause mild to serious gastrointestinal upsets. A few, the amanitas in particular, are deadly poisonous as they produce toxins that degrade RNA in the liver as it attempts to metabolize them. Symptoms of poisoning by these mushrooms do not show until four to five hours after ingestion, frequently too late for blood dialysis. Blood dialysis is currently the only treatment other than a complete liver transplant! The caps of gill and pore fungi are always situated so that the basidial layer is perpendicular to the ground. Basidiospores are dependent on gravity to fall out of the gills or pores. Any intervening fungal tissue would defeat the reproductive process. Predaceous fungi are extremely interesting. One species possesses a noose derived from specialized haustorium cells. When a nematode enters the noose and touches the cell wall, the noose contracts and traps it. The fungus then digests the nematode. Another form has cloverleaf-shaped sticky pads that attach to various soil organisms. Attempts are being made to culture such fungi on an agricultural level because soil nematodes destroy enormous amounts of commercial crops each year. • Discuss wheat rust and its primary and secondary hosts. Eradicating barberry bushes eliminates the second host and, therefore, the infection on the wheat crop. Several naturally rust-resistant strains of wheat have also recently been developed. • HIGHER LEVEL ASSESSMENT Higher level assessment measures a student’s ability to use terms and concepts learned from the lecture and the textbook. A complete understanding of biology content provides students with the tools to synthesize new hypotheses and knowledge using the facts they have learned. The following table provides examples of assessing a student’s ability to apply, analyze, synthesize, and evaluate information from Chapter 32. Application • Have students describe similarities between the nutritional needs of bacteria and fungi. • Have students explain if all fungi can be inhibited by chemicals that prevent the successful completion of meiosis. • Ask students to distinguish between the mushrooms of Ascomycetes and Basidiomycetes. Analysis • Have students compare and contrast fungi and plants. • Have students compare and contrast fungi and protists. • Ask students to explain why antibiotic treatments of humans usually lead to an increase in fungal infections. Synthesis • Ask students explain a way that mycorrhizae can be exploited in agriculture. • Have students design a strategy to classify a newly discovered fungus that was found dried and dead in the body of a 7000 year old mummified body. • Ask the students come up with a strategy using fungi to reduce the amount of household wastes entering landfills. Evaluation • Ask students evaluate the effectiveness and safety of a home remedy that recommends eating moldy oranges as a way of fighting off bacterial infections. • Ask students to evaluate the strengths and weaknesses of using yeast as a model for human genetics. • Ask students to evaluate the effectiveness and safety of any medical treatment used to kill pathogen fungi in humans. VISUAL RESOURCES Show slides, lots of them, illustrating the variety in shapes, forms, and color. • Bring in as many examples of fungi as you can. A greater variety is now available in grocery stores than ever before. These may include the Japanese Shiitake (black forest mushroom), Pleurotus ostreatus (oyster mushroom), Auricularia (ear fungus), dried morelles, and many chanterelles as well as the ever present Agaricus campestris bisporus (have two rather than four basidiospores). • IN-CLASS CONCEPTUAL DEMONSTRATIONS A. Computer Modeling of Fungal Hyphae. Introduction Few students realize that researchers use computerized mathematical modeling systems to study the growth of fungi. This demonstration provides a visual way of demonstrating the growth of a fungal mycelium. It gets students thinking about the ways biological growth patterns obey the laws of physics. Materials • Computer with Media Player and Internet access • LCD hooked up to computer • Web browser linked to the Lindenmayer systems in microbiology website hosted by La Trobe University, Bendigo, Australia at http://coco.ccu.uniovi.es/malva/sketchbook/lssketchbook/examples/fungal/fungal.htm. Procedure & Inquiry 1. Review the stages of fungal germination and growth to the class. 2. Then explain to students that mathematic modeling is often used to better study the growth of fungi. Tell them that the information is often useful in understanding how to control fungal growth for commercial and medical applications. 3. Start the first animation showing the rapid fungal growth. 4. Ask the students to explain any growth patterns including identifying older and younger parts of the mycelium. 5. Start the first animation showing the slowed down fungal growth. 6. Again, ask the students to explain any growth patterns including any uniformity or irregularities in the growth. 7. Ask the students to explain if the growth model shown here is applicable to understanding plant growth. LABORATORY IDEAS A. Spore Germination Factors This activity has students design an experiment to investigate the environmental conditions needed for fungal spore germination. They will use spores collected from Aspergillus and Penicillium cultures to test their hypotheses. a. Tell students that they will be investigating the conditions needed for fungal spore germination in two types of fungi. b. Provide students with the following materials a. Sporulating culture of Aspergillus niger b. Sporulating culture of Penicillium sp c. Petri plates with sterile potato dextrose agar d. Forceps e. Dropper f. Covered plastic containers large enough to place Petri plates g. Anaerobic pack or generator as used in microbiology h. Light source i. Thermometers j. Small hygrometer (measuring atmospheric moisture) k. Test tubes l. Sterile water c. Instruct students to design an experiment to test the environmental conditions needed for spore germination for two different fungi. d. Have the students collect spores from the colonies and place the spores in test tubes containing 1 ml of sterile water. The water should ten be mixed thoroughly. e. 0.25 ml of the mixture spore solution should then be transferred with a dropper to the Petri plate. f. The inoculated plates should then be subjected to the different environmental conditions. g. Students should plan to take a week to collect their data. h. Have the students prepare a report explaining the conditions necessary fungal spore germination. They should have literature supporting if their findings are consistent with the conditions needed for fungi. LEARNING THROUGH SERVICE Service learning is a strategy of teaching, learning and reflective assessment that merges the academic curriculum with meaningful community service. As a teaching methodology, it falls under the category of experiential education. It is a way students can carry out volunteer projects in the community for public agencies, nonprofit agencies, civic groups, charitable organizations, and governmental organizations. It encourages critical thinking and reinforces many of the concepts learned in a course. 1. Have students do a lesson and a presentation about safety with mushrooms to elementary school students. 2. Have students set up a “mushroom garden” for a local school or library. 3. Have students design a brochure on fungal diseases of humans for a local health clinic. 4. Have students volunteer to assist a local mycological society. CHAPTER 26: PLANTS WHERE DOES IT ALL FIT IN? Chapter 26 is consistent with strategies of Chapters 23 and 24 and highlights plant diversity of seed and seedless plants. Students should be encouraged to recall the principles of eukaryotic cell structure and evolution associated with the particular features of plant cells. The information in Chapter 26 does not stand alone. Students should know that plants and other organisms are interrelated and originated from a common ancestor of all living creatures on Earth. SYNOPSIS Terrestrial plants, most likely evolved from a single green algal ancestor, which still remains a mystery today. Plants are described as a group of organisms derived from multicellular algae as evidenced by their chlorophyll b¬ containing chloroplasts. Characteristics of plants include: photosynthetic, embryo protection, multicellular haploid and diploid phases, and presence/absence of conducting systems, cuticles, and stomata. All plants exhibit a haplodiplontic life cycle having multicellular haploid and diploid stages. A haploid gametophytic generation or “gamete plant” gives rise to haploid gametes that undergo syngamy to produce a diploid sporophytic generation or “spore plant” which produce haploid spores. Meiosis takes place in the sporangia, reproductive structure on the diploid sporophyte, and produce producing four haploid spores that then divide by mitosis that develop into the multicellular, haploid gametophytes. The more primitive plants exhibit prominent gametophytes and reduced, dependent sporophytes while the more advanced plants are primarily sporophytic with reduced, dependent gametophytes. Heterosporous plants produce two different kinds of spores, homosporous plants produce only one kind of spore. Three phyla represent approximately 24,700 species of nonvascular plants; the Bryophyta (mosses), Hepaticophyta (liverworts), and Anthocerotophyta (hornworts). Although diverse and not truly related, they share four primary characteristics: (1) photosynthetic, independent gametophytes, (2) a nutritionally dependant sporophyte attached to the gametophyte, (3) they require water for fertilization, and (4) they are small in size with the gametophyte more conspicuous than the sporophyte. Mosses possess a central axis of rudimentary water conducting tissue found in leaflike structures and anchored to the substrate by rhizoids. Reproductive structures consist of the female gametangia (archegonia) that produce a single egg and male gametangia (antheridia) which produce numerous sperm. Sperm are released from an antheridium and swim using their flagella through rainwater to the archegonia, uniting with a haploid egg forming a diploid zygote. Zygote divides by mitosis and develops into the sporophyte, where mother cells undergo meiosis producing four haploid spores. Liverworts and hornworts lack any form of vascular tissue. All three phyla are well suited for wide ranging terrestrial habitats, from arid and cold to warm and moist. Vascular plants possess efficient conducting systems comprised of two elements. Phloem cells carry carbohydrates away or down from leaves where they are manufactured. Xylem elements transport water and minerals up from the roots. The less ¬advanced, seedless vascular plants are similar to mosses; they form antheridia and archegonia, produce free-swimming sperm and require water for fertilization. They include closely related Pterophyta (ferns, horsetails, whisk ferns) distantly related Lycophyta (club mosses). In these two phyla there is a greater development of the sporophyte stage, now photosynthetic and nutritionally independent of the gametophyte. The ferns with about 365 genera are the most abundant seedless vascular plants and exhibit diverse morphologies. Most possess horizontal, underground stems called rhizomes and have leafy fronds that develop from fiddleheads. Nearly all are homosporous with distinctive sori containing sporangia that contain haploid spores. The horsetails comprise only one genus, homosporous with motile sperm, either photosynthetic or nonphotosynthetic. Whisk ferns comprise two genera, are homosporous, have motile sperm, no leaves, and little differentiation between roots and shoots. Today, there are over 300,000 species of seed plants. Seed producing, vascular plants are heterosporous, lack antheridia, possess non-flagellated sperm, and only a few produce archegonia. All seed plants are heterosporous. Their microgametophytes (male gametes) are called pollen grains and are released directly into the environment. Their megagametophytes (female gametes) are held within the ovules and are pollinated when contacted by pollen grains. Pollination and fertilization may be separated by long periods of time. Five phyla make up the seed producing, vascular plants including the: angiosperms that produce seeds enclosed within fruits including the phyla of Anthophyta (flowering plants) and gymnosperms which are plants that produce naked seeds including phylums: Coniferophyta (pines, spruces, firs, yews, redwoods and other conifers), Cycadophyta (cycads), Gnetophyta (gnetophytes), and Ginkgophyta (ginkos). All ginko species are in one genus, have flagellated and motile sperm, deciduous trees. Gnetophyta species are in one of three genera, have nonmotile sperm, and are the only gymnosperms with vessels. Cycadophyta phyla include 10 genera, seeds are in cones, sperm are flagellated and motile and include palmlike plants. Coniferophyta comprises about 50 genera of conifers, have nonmotile sperm, needlelike or scalelike leaves, and seeds found in cones. The Angiosperms phyla Anthophyta contain over 250,000 known species of flowering plants and are divided into two monophyletic classes: the eudicots or “dicots,” which are made up of about 175,000 species and are the more primitive of the two, and the second lineage that gave rise to the monocots and magnolias with about 65,000 species. Plants in these two lineages, monocots and dicots, differ according to the number of cotyledons, leaf venation, presence of lateral meristems, and number of flower parts. Included in the dicots are the majority of fruit and nut trees, shrubs, snapdragons, mints, and a majority of all vegetables and fruits. Many monocot plants are mostly annual plants and include the grasses, grains, lilies, cattails, palms, agaves, yuccas, pondweeds, orchids, and irises. All flowers, modified stems with modified leaves, share certain features. The flower originates as a bud at the end of a pedicel (stalk), which expands to form the receptacle and other flower parts including an outermost whorl of sepals (green and leaf like), followed by a whorl of colored petals attracting pollinators. The third whorl is comprised of the androecium or the stamens, made up of the anther and filament. At the center of this whirl is the gynoecium, the female structures, the carpels. The carpel contains the stigma, style, and the fruit-developing ovary, containing one to hundreds of ovules. Angiosperms undergo double fertilization where one sperm cell fuses with the egg to produce the zygote while a second sperm fuses with two polar nuclei to form the nutritive triploid endosperm. Angiosperm evolutionary innovations include flowers to attract pollinators, fruits that protect the embryo and aid in its dispersal, and double fertilization providing for nutritive tissue for the growing embryo. LEARNING OUTCOMES 26.1 Plants are Multicellular Terrestrial Autotrophs with Embryos 1. Explain the relationship between green algae and plants. 2. Identify two major environmental challenges for land plants and associated adaptations. 3. Distinguish between a sporophyte and a gametophyte. 26.2 Bryophytes Have a Dominant Gametophyte Generation 1. Describe adaptations of bryophytes for living in terrestrial environments. 2. Distinguish between a sporophyte and a gametophyte. 3. Explain the relationship between moss gametophyte and sporophyte. 26.3 Vascular Plants Evolved Roots, Stems, and Leaves 1. Distinguish between xylem and phloem. 2. Explain the evolutionary significance of roots, leaves, and seeds. 26.4 Lycophytes Have a Dominant Sporophyte Generation 1. Explain the features that differentiate lycophytes from bryophytes. 26.5 Pterophytes Are Ferns and Their Relatives 1. Compare pterophytes and lycophytes. 2. Describe the characteristics of whisk ferns and horsetails that distinguish them from ferns. 26.6 Seed Plants Were a Key Step in Plant Evolution 1. List the evolutionary advantages of seeds. 26.7 Gymnosperms Are Plants with “Naked Seeds” 1. Explain why conifer reproduction favors forest formation. 2. Describe the three no conifer gymnosperms. 26.8 Angiosperms Are Flowering Plants 1. List the defining features of the angiosperms. 2. Describe the structure of an angiosperm flower. 3. Explain double fertilization and its outcome. COMMON STUDENT MISCONCEPTIONS There is ample evidence in the educational literature that student misconceptions of information will inhibit the learning of concepts related to the misinformation. The following concepts covered in Chapter 26 are commonly the subject of student misconceptions. This information on “bioliteracy” was collected from faculty and the science education literature. • Students do not fully understand the origins of endosymbionts in plants. • Students believe that plants do not carry out cellular respiration. • Students believe that plants lack tissues and organs. • Students do not know that a change in ploidy is associated with alternation of generations. • Students confuse spores with pollen. • Students believe that the pollen of any plant can be found in the wind. • Students do not equate pollination with sexual reproduction. • Students think pollen are one and the same as sperm. • Students are unaware that plants produce eggs. • Students are unaware that plants undergo embryological development. • Students believe that all flowers are insect pollinated. INSTRUCTIONAL STRATEGY PRESENTATION ASSISTANCE This chapter introduces a lot of new words. Simplify this by breaking the words into their roots when possible: “phyte” means plant; “micro,” “andro,” and “anth” are associated with male structures; “mega,” “gyno,” and “arch” are associated with female parts. Stress the difference between nonvascular and vascular, seedless vascular, and how the haplodiplontic life cycle relates to both the gametophyte and the sporophyte. The multitude of plant life cycles can become very confusing. Present as few as possible to make your point. It is better to understand the major changes associated with evolution and specialization. The evolution from a dominant gametophyte to a dominant sporophyte is specific to plants. HIGHER LEVEL ASSESSMENT Higher level assessment measures a student’s ability to use terms and concepts learned from the lecture and the textbook. A complete understanding of biology content provides students with the tools to synthesize new hypotheses and knowledge using the facts they have learned. The following table provides examples of assessing a student’s ability to apply, analyze, synthesize, and evaluate information from Chapter 30. Application • Have students speculate if plants would have evolved without endosymbionts. • Have students describe what part of the life cycle of ferns would not be able to develop if meiosis was inhibited. • Have students describe what part of the angiosperm life cycle would not be able to develop if meiosis was inhibited. • Ask students to identify the equivalent structure of sori in ferns to flowering plants. Analysis • Have students compare and contrast moss and fern life cycles. • Have students compare and contrast gymnosperm and angiosperm life cycles. • Ask students to distinguish between the role of meiosis in mosses (discussed in chapter 30) and angiosperms. Synthesis • Ask students to explain the possible effects on the different groups of plants if global climate change were to cause a particular region to decrease rainfall by half the usual amount. • Have the students describe the impacts on the different groups of plants if pesticides are regularly sprayed in an area. • Ask students to design a hypothetical nature preserve that has the ideal growing conditions for mosses, ferns, gymnosperms, and angiosperms. Evaluation • Ask students to evaluate the effectiveness and safety of an herbicide that inhibits the function of plant vasculature and which plants would be affected. • Ask students to evaluate a plan reintroduce extinct plants into an area where they once grew. • Ask students to evaluate a plan by a city developer who wants to replace native gymnosperms with ornamental angiosperms. VISUAL RESOURCES It is important to show photographs of the various phyla of plants. Many are quite inconspicuous, and others are found only in specialized habitats. IN-CLASS CONCEPTUAL DEMONSTRATIONS A. Animated Life Cycles. Introduction A lecture on plant classification is best supplemented with animations of plant life cycles. This demonstration provides a visual way of reinforcing the life cycles of the major seedless plant groups. Materials • Computer with Shock Wave Media Player and Internet access • LCD hooked up to computer • Web browser linked to the University of Massachusetts Biology website at http://intro.bio.umb.edu/111-112/112s99Lect/life-cycles.html. Procedure & Inquiry 1. Review the differences in plant life cycles to students. 2. Load up the animation on Moss Life Cycle. 3. Start the animation and pause it to ask students a question about the event they witnessed. 4. At the end the animation, ask students to describe particular features of the life cycle. 5. Repeat steps 3 and 4 for the Fern and Angiosperm animations. 6. Ask the students to compare and contrast the plant life cycles. LABORATORY IDEAS A. A Colorful View of Plant Metabolism This activity provides students with a visual way to investigate the metabolic processes of plants using aquatic plants as a model organism. Students are asked to design an experiment that measures the metabolic processes of plants under dark and light growing conditions. a. Tell students that they designing an experiment to measure the metabolic processes of plants under light and dark conditions. b. Explain to the class that they will be provided with a pH indicator called phenol red as a way of measuring metabolism. Phenol red is pink under basic conditions, orange under neutral conditions, and yellow under acidic conditions. c. Provide students with the following materials a. Growth solution containing the following chemical composition: i. 0.01M monobasic sodium phosphate ii. Solution adjusted to pH 7 b. Test tubes with loose fitting caps as used in microbiology c. 0.1% solution of phenol red d. Elodea e. Euglena f. Light source g. Aluminum foil d. Ask students to research why pH is an indicator of plant metabolism. Give a hint that CO2 affects the pH of a solution. e. Instruct students to design two model experiments using elodea and euglena and to indicate plant metabolism under light and dark growing conditions. f. Remind the students to think about the role of controls in the experiment. g. This experiment may take 2 to 3 days to collect results h. Have the student prepare a report on their findings that can be compared in some format to the data from the whole class. B. Life Cycle Issues This activity has students design and experiment to test the environmental conditions needed for plant germination. They will use Fast Fern spores as a model plant. i. Tell students that they will be investigating the conditions needed for plant germination. j. Provide students with the following materials a. Wisconsin Fast Fern (C-Fern) spores b. Petri plates with sterile C-Fern media for Fast Ferns c. Forceps d. Covered plastic containers large enough to place Petri plates e. Anaerobic pack or generator as used in microbiology f. Light source g. Thermometers h. Small hygrometer (measuring atmospheric moisture) i. Sterile water k. Instruct students to design an experiment to test the environmental conditions needed for plant germination for spores. l. Students should plan to take a week to collect their data. m. Have the students prepare a report explaining the conditions necessary for spore germination. They should have literature supporting if their findings are consistent with the conditions needed for all plant spores LEARNING THROUGH SERVICE Service learning is a strategy of teaching, learning and reflective assessment that merges the academic curriculum with meaningful community service. As a teaching methodology, it falls under the category of experiential education. It is a way students can carry out volunteer projects in the community for public agencies, nonprofit agencies, civic groups, charitable organizations, and governmental organizations. It encourages critical thinking and reinforces many of the concepts learned in a course. 1. Have students prepare a presentation about different types of plants to elementary school students. 2. Have students perform volunteer service at a nature center. 3. Have students speak to a civic group about the importance of having plants in cities and urban areas. 4. Have students work with a local environmental group on plant conservation projects. CHAPTER 27: ANIMAL DIVERSITY WHERE DOES IT ALL FIT IN? Chapter 27 takes the same strategy as Chapters 23 through 25 and highlights the diversity of animals. Students should be encouraged to recall the principles of eukaryotic cell structure and evolution associated with the particular features of animal cells. Multicellularity should also be reviewed. The information in chapter 27 does not stand alone. Students should know that animals and other organisms are interrelated and originated from a common ancestor of all living creatures on Earth. • • SYNOPSIS • • Animals are distinctly different from other life forms studied thus far. They are multicellular, heterotrophic, have no cell walls, move rapidly and in complex ways, are diverse in form and habitat, exhibit primarily sexual reproduction, undergo embryonic development, and have unique tissues. The animal kingdom is divided into two subkingdoms: Parazoa (beside animals) and Eumetazoa (true animals). Both are derived from the same unicellular choanoflagellate ancestor. Sponges are the most familiar parazoans; they are typically asymmetrical and lack both tissues and organs. The 35 phyla of eumetazoans possess definite shape, symmetry and tissues that are organized into organs and organ systems. The Eumetazoans are further divided into Radiata (diploblastic), animals with radial symmetry and two tissue layers of ectoderm and endoderm; and, Bilateria (triploblastic), animals with bilateral symmetry and three tissue layers of ectoderm, mesoderm, and endoderm. The bilateral animals are split further into groups based on other characteristics. • Animal phyla show five key transitions in body plan as they evolve from simple to more complex forms. First, there was the evolution of tissues from no defined tissues and organs to distinct tissues with highly specialized cells. The sponges lack tissues; all other animals possess tissues. Second, there was the evolution of symmetry-asymmetry (animals with no defined symmetry), radial symmetry (animals with body parts arranged around a central axis), and bilateral symmetry (body design in which the body has a right and left halves). Porifera, the sponges, are asymmetrical, lacking any kind of symmetry. Radiata (cnidarians and ctenophora) exhibit radial symmetry while all other animals are bilaterally symmetrical. Bilateral symmetries allows for the differential adaptation of various parts of the body. It also supports the evolution of cephalization with the localization of sensory organs at one end. The third key transition is the evolution of a body cavity. Three basic kinds of body plans evolved in the Bilateria: acoelom (no body cavity), pseudocoelom (false body cavity located between the mesoderm and endoderm), and coelom (fluid-filled true body cavity that develops entirely in the mesoderm). Acoelomates like flatworms possess no body cavity and are commonly called solid-bodied worms. Seven animal phyla are pseudocoelomates, possessing a pseudocoel, including the roundworms found in phylum Nemotoda. Most members of the animal kingdom are coelomates. The gut and other internal organs are suspended within the coelom. The advent of this type of body cavity necessitated the development of a more complex circulatory system to ensure that all organs receive oxygen and nutrients. The fourth transition separates protostome and deuterstome development. Cleavage patterns differ as the protostomes undergo spiral cleavage and the deuterstomes undergo radial cleavage. Additionally, in protostomes the blastopore becomes the mouth while in deuterostomes the blastopore becomes the anus. The evolution of segmentation is the fifth key transition. Segmentation provides for more efficient locomotion and increased protection from damage due to the replication of organs in each segment. True segmentation is found in annelids, arthropods, and chordates. • The way animals are being classified is continually being reviewed and reevaluated. The traditional scheme had been in existence for almost a century and had always presented problems with its simplistic either/or organization. Now, new taxonomical comparisons using molecular data, the field of molecular systematics uses unique genomic sequences to identify related groups, have come to different conclusions. Morphological characters that have traditionally been used to construct animal phylogenies—segmentation, coeloms, and jointed appendages—are not the conservative characteristics as once believed. • • The coelom appears to have evolved just once in an ancestor of the clade comprising protostomes and deuterostomes. Protostomes are further divided into two major clades (based on molecular systematics): Spiralians and Ecdysozoans. Spiralians, composed of Lophotrochozoans and Platyzoa, are animals that grow by adding additional mass to an existing body. Deuterostomes, comprised of Echinoderms and Chordates share a mode of development that separates them from other animals. • • Phylum Porifera includes about 7000 species of colonial marine and 150 species of freshwater sponges. They are sessile as adults, filter feeders dependent on food-laden water circulating through pores in their body wall. Sponges exist at a cellular level, being composed of multiple cell types. There is little coordination between cells in a sponge, although there is some specialization according to function. Their internal cavity is lined with flagellated choanocytes (collar cells) that strongly resemble a choanoflagellate protist, their likely ancestor. The intermediate mesenchyme layer contains amoeboid cells called amoebocytes that secrete hard mineral needles called spicules and tough protein fibers called spongin. The outer layer consists of an outer epithelial layer of flattened cells similar to epithelia found in other animals. Sponges exhibit sexual reproduction by spewing gametes into surrounding environment. Larval sponges are free-swimming at the planktonic stage, eventually settling down on a suitable substrate to undergo the transformation into adult sponges. • Radiata include the phylas Cnidaria and Ctenophora are radially symmetrical acoelomates that have two distinct tissue layers, an outer ectoderm and inner endoderm. Most Cnidarians exhibit two diploid body forms: the cylindrical, upward ¬facing polyp and the umbrella-shaped, downward-facing medusa. Polyps may reproduce asexually by budding, producing new polyps or medusa. Medusae reproduce sexually in which fertilized eggs give rise to free-swimming, multicellular, ciliated larvae known as planulae. They are carnivores that secrete digestive enzymes into a primitive gut. The gut opening serves as both mouth and anus. They are the first organisms capable of digesting particles larger than a single cell, although the particles must still be degraded intracellularly. Cnidarians also possess unique stinging cells, or cnidocytes that contain harpoon¬like nematocysts. They are divided into four classes: class Hydrozoa, the 2700 species of hydroids such as Obelia and Portuguese man-of-war; class Scyphozoa, the 200 species of jellyfish that have the dominant medusa stage; class Cubozoa, the box jellyfish that have a box-shaped medusae with a reduced or unknown polyp stage; and, class Anthozoa, the largest class of cnidarians with approximately 6200 species of sea anemones and corals. Members of the phylum Ctenophora, the comb jellies or sea walnuts, are abundant in the open ocean. They are structurally quite different from the cnidarians; they have anal pores, two retractable tentacles, and propel themselves through the water with eight comb like plates of fused cilia. • • Two phyla are characterized by being bilaterally symmetrical, but possess no body cavity. The phylum Platyhelminthes consist of 20,000 free-living and parasitic species. They possess three distinct tissue layers and complete organ systems, but lack an internal cavity (acoelomates) other than a digestive tract. They are bilaterally symmetrical, dorso-ventrally flattened animals, hence the common name of the group, the flatworms. Their digestive system is similar to that of the cnidarians, but more highly branched. They additionally possess excretory and nervous systems; the latter includes specialized anterior sensory systems used to find food. Most flatworms are hermaphroditic, with each individual containing both male and female sexual structures. Flatworms are also capable of asexual reproduction—each part can regenerate an entirely new flatworm. There are three classes of flatworms: Class Turbellaria, Class Trematoda and Class Cestoda. Members of class Turbellaria are free-living inhabiting lakes, ponds, sea and moist terrestrial habitats. The common planaria, genus Dugesia, is found in this class. Class Trematoda consist of mostly internal parasitic flukes, such as the liver fluke, Clonorchis sinensis and blood fluke of the genus Schistosoma. Class Cestoda consist of yet another parasitic form of flatworms, the tapeworms. Tapeworms occur in the intestines of about a dozen different vertebrate species, including humans. A familiar tapeworm is Taenia saginata, the beef tapeworm. Some 900 species of ribbon worms comprise the phylum Nemertea. They are the simplest animals in which blood flows in specific vessels and that possess a complete digestive system with both an anus and mouth. • Phylum Rotifera consist of about 1800 recognized species of rotifers. They are ubiquitous microscopic animals characterized by an anterior crown of cilia that is adapted for feeding and locomotion. • Phylum Mollusca consist of the mollusks that include a wide variety of animals: snails, slugs, clams, scallops, cuttlefish, octopuses, squids, and many others. All mollusks are bilaterally symmetrical, have a visceral mass, and a muscular foot. Digestive, reproductive, and excretory organs are located within the visceral mass. Respiratory organs, gills or lungs, are located within the mantle cavity. Many of them possess durable external shells, a product of the outer layer of the mantle; others have internal shells and a few possess no shell at all. Most mollusks exhibit a trochophore larval stage that may be followed by a second veliger larval stage. They are divided into seven classes, the ancestral form most closely resembling the chitons, class Polyplacophora. The class Gastropoda consists of over 40,000 species of snails, slugs and similar animals that have a distinct head with tentacles and glide on a mucus layer that is secreted by the foot. Their visceral mass may be enclosed in a single spiral shell and is asymmetrical because of torsion during development. Class Bivalvia are made up of about 10,000 species of bivalves. Bivalve mollusks possess two shells hinged together at the dorsal edge. They lack distinct heads or radulas and are generally filter feeders. Octopuses, squids, and nautiluses comprise the class Cephalopoda. They have distinct heads and a series of tentacles evolved from the muscular foot. Cephalopods have highly developed nervous systems with elaborate eyes. They are the most intelligent and the largest invertebrate. • Segmentation was another evolutionary key transition feature. Phylum Annelida or the Annelids are most likely the first segmented worms. Segmentation allows for more efficient locomotion as it increases overall flexibility. If an organ in one segment is damaged, duplicate organs in other segments continue to operate. Each segment is an individual hydrostatic unit, capable of independent contraction that possesses external chitinous bristles called setae. Annelids are constructed as a tube (the digestive tract) within a tube (the coelom). They have an organized nervous system with a well-developed brain and separate ganglia in each segment. Annelids possess a closed circulatory system with pulsating “hearts,” but lack discrete respiratory organs. Gas exchange occurs across the surface of their skin, limiting their size and restricting them to moist environments. They are divided into three classes: class Polychaeta (clamworms, plume worms, scaleworms, lugworms, twin-fan worms, sea mice, peacock worms and other marine worms), class Oligochaeta (earthworms), and class Hirudinea (leeches). Polychaetes or marine worms are active predators and clearly ancestral to the other classes and related to mollusks by their trochophore larvae. They move about by fleshy, paddlelike flaps called parapodia. Class Oligochaeta or the earthworms are represented by both terrestrial and aquatic forms, although the most common form is readily found in nearly everyone’s backyard soil. Class Hirudinea consist of the highly specialized leeches, frequently parasitic worms and that clearly evolved from the Oligochaetes. Leeches have been used in medicine for centuries and are still used following surgery to help remove excess blood from tissues. • Two phyla of mostly marine animals are characterized by a lophophore, a circular or U-shaped ridge around the mouth that functions in gas exchange and food collection. They include the Bryozoans, which are colonial animals, and Brachiopoda, which are solitary lophophorates. Many Brachipodia species resemble clams with two calcified shells. Phylum Phoronida consist of about 10 species. Phoronids secrete a chitinous tube and live its life within it, extend tentacles to feed, have a U-shaped gut, and lie buried in the sand or attached to rocks. • The Ecdysozoans are molting animals. The phylum Nematoda, a large phylum of ecdysozoans consisting of 20,000 recognized species, includes the nematodes, eelworms, and roundworms. They are bilaterally symmetrical, cylindrical, unsegmented worms that whip from side-to-side as they possess only longitudinal muscles. The pseudocoel serves as a hydrostatic skeleton against which the body muscles contract. Their digestive system is one-¬way with a mouth, pharynx, gut, and anus. These worms are generally parasitic, either on plants or in animals and cause enormous agricultural damage. Some nematode-caused diseases include: trichinosis caused by Trichinella; pinworm infestation by Enterobius; intestinal roundworm infection by Ascaris; and elephantiasis caused by the Filaria worm. • The development of jointed appendages and an exoskeleton are characteristics of the Arthropoda. With the advent of rigid exoskeletons, jointed appendages were necessary to allow efficient movement in a terrestrial environment. These appendages are modified into various types of antennae, mouthparts, and legs. All arthropods have jointed appendages that may be modified into specialized structures, such as antennae, mouthparts, or legs. Although they lack overall intelligence, arthropods are ecologically a highly successful group, with over 1,000,000 known species that comprise about two-thirds of all the named species on earth. They can be found in all habitats on earth and may be a result of their generally small size. All arthropods have a rigid external skeleton or exoskeleton made of chitin and protein, which protects the animal from predation and prevents water loss. The exoskeleton is both tough and flexible, but must be shed periodically, a periodic ecdysis in order to grow larger. It is unlikely that extremely large arthropods could survive because of the large mass of exoskeleton and the necessity to molt the exoskeleton for growth. Additionally, all arthropod bodies are segmented. Some individuals have a large number of separate segments, while others have segments that are fused into functional groups through the process of tagmatization. The compound eye is another important structure in many arthropods as it is made up of many visual units called ommatidia as opposed to the single lens, simple eye. They are internally characterized by a reduction of the coelom to mere cavities surrounding the reproductive organs and some glands. They possess an open circulatory system with a longitudinal heart and no closed blood vessels. Although arthropods possess well developed nervous system with an anterior brain, the majority of body activities are actually controlled by ventral ganglia. Because of this, many insects continue activities for a period of time even when decapitated. In addition, the brain acts through inhibition rather than stimulation as in the vertebrates. The closed respiratory system of the terrestrial arthropods is made up of a series of hollow, branching tubes called tracheae. Some arthropods have book gills or book lungs alone or in addition to tracheae, while others possess typical aquatic gills. Several forms of excretory systems exist among the arthropods; the primary component of terrestrial arthropods is the Malpighian tubules. The phylum Arthropoda is traditionally divided according to the structure of appendages. The 35,000 species of crustaceans is a group of primarily aquatic organisms including crabs, shrimps lobsters, crayfish, barnacles, water fleas, pillbugs, and others. Most possess two pairs of antennae, three types of chewing appendages, and various numbers of pairs of legs. The appendages of the crustaceans are biramous or two-branched. Decapod crustaceans include shrimp, lobsters, and crabs. Terrestrial and freshwater crustaceans include about 4500 species with the most familiar being the pillbugs, sowbugs, sand fleas, and the copepods. Sessile crustaceans include barnacles. Arachnida consist of over 57,000 species of spiders, mites, ticks, and scorpions. All possess chelicerates, fangs, or pincers that evolved from the most anterior pair of appendages. The next pair of appendages, pedipalps, resembles legs but is not used for locomotion, but instead is used as specialized copulatory organs. The order Araneae consists of about 35,000 species of spiders. The order Acarni consists of about 30,000 species of mites and ticks. Class Merostomata includes the horseshoe crabs. It is likely that the horseshoe crabs evolved from the now extinct trilobites. The class Pycnogonida includes the sea spiders. Insecta is the largest group of organisms on the earth consisting of approximately 90,000 described species. They characteristically have three body segments with three pairs of legs attached to the thorax. Some insects possess wings, although these structures are not derived from appendages as are the wings of vertebrates. They possess a wide variety of sense receptors that are involved with reproductive activities as well as food collection. Insects undergo hormonally controlled metamorphosis or molting from juvenile to adult stages. Some insects, like grasshoppers, exhibit simple metamorphosis. Others like bees, house flies, and butterflies undergo complete metamorphosis. This large group includes the: order Coleoptera (beetles); order Diptera (flies); order Lepidoptera (butterflies, moths); order Hymenoptera (bees, wasps, ants), order Hemiptera (true bugs, bedbugs); order Homoptera (leafhoppers, aphids, cicadas; order Orthoptera (grasshoppers, crickets, roaches); order Odonata (dragonflies); order Isoptera (termites); and order Siphonaptera (fleas). The group Chilopoda (centipedes) and group Diplopoda (millipedes) have bodies that consist of a head region followed by many segments bearing paired appendages. There are 2500 known species of centipedes; all are carnivorous mostly feeding on insects, with the first pair of appendages modified into a pair of poison fangs. Their bites can be toxic to humans, painful and dangerous. There are over 10,000 species of millipedes and probably six times this number exists. They are herbivores, feeding on decaying vegetation and can excrete a bad-smelling fluid that is protection against attacks. The 6000 species belonging to the phylum Echinodermata is unusual in that its larvae exhibit bilateral symmetry, while the adults are radially symmetrical. The secondary radial symmetry may be associated with the mobility of the phylum. Bilateral symmetry is very important for mobile organisms, in echinoderms the larval form. The adults are relatively sessile, appropriate for radial organisms. They possess an endoskeleton composed of calcium-plate ossicles covered by a thin epidermis. They have no head or brain and their bodies follow a five-part plan. Echinoderms have a unique water vascular system that controls the extension and contraction of flexible tube feet used in locomotion and/or feeding. The coelom connects with a complicated system of tubes and helps provide circulation and respiration. Respiration and waste removal occurs across the skin through projections called skin gills. They are capable of extensive regeneration in addition to normal sexual reproduction. Echinoderms are divided into six visually different classes. The class Crinoidea includes the sea lilies and feather stars, multi-armed filter feeders whose mouth and anus are located on the upper surface. Class Asteroidea includes the sea stars, active marine predators. Class Ophiuroidea consist of the brittle stars that appear similar to sea stars, but their arms are set off more sharply from the central disk. Sea urchins and sand dollars, lacking arms, are two of the 950 living species that are members of the class Echinoidea. These latter three classes have mouths located on the under surface (aboral surface). The class Holothuroidea least resembles the other echinoderms. Their body form is well described by their common name, sea cucumber. Their ossicles are microscopic plates embedded in a leathery skin and they lack spines. The most recently discovered class Concentricycloidea are commonly called sea daisies. These disk-shaped animals have the typical five-part radial symmetry, but lack arms. Their tube feet are arranged along the edge of the disk, not along radial lines like the other classes of echinoderms. Both species are unusual with regard to their digestion. One has a saclike stomach without intestine or anus. The other completely lacks a digestive system, absorbing nutrients through a membrane on the mouth. The phylum Chordata includes the animals with which we are most familiar and most closely related. Their principal features are: a single, hollow, dorsal nerve cord; a flexible, dorsal notochord; pharyngeal slits; and a postanal tail. All chordates have these four characteristics at some time in their development. LEARNING OUTCOMES 27.1 The Diversity of Animal Body Plans Arose by a Series of Evolutionary Innovations 1. Describe some common features of animals. 2. Compare and contrast radial and bilateral symmetry. 3. Describe the types of body cavities found in animals. 4. Compare and contrast protostome and deuterostome development. 5. Explain how segmentation is an important innovation. 27.2 Molecular Data are Clarifying the Animal Phylogenetic Tree 1. Explain how our understanding of animal phylogeny has changed. 2. Contrast spiralians and ecdysozoans. 27.3 True Tissue Evolved in Simple Animals 1. Explain the function of choanocytes. 2. Describe the features of Cnidarians. 27.4 Platyzoans Are Very Simple Bilaterians 1. Describe the features of platyhelminthes. 2. Describe the features of rotifers. 27.5 Mollusks and Annelids Are The Largest Groups of Lophotrochozoans 1. Differentiate between different types of mollusks. 2. Explain how circular and longitudinal muscles facilitate moving a segmented body. 3. Discuss the question of symmetry of ctenophores. 27.6 Lophophorates Are Very Simple Marine Organisms 1. Describe how bryozoans obtain food. 27.7 Nematodes and Arthropods Are Both Large Groups of Ecdysozoans 1. Describe the characteristic features of nematodes. 2. List the four classes of insects. 3. Explain the advantages and disadvantages of an exoskeleton. 4. Compare and contrast classes of arthropods. 27.8 Deuterostomes Are Composed of Echinoderms and Chordates 1. Describe the basic body plan for echinoderms. 2. Describe the defining features of chordates. COMMON STUDENT MISCONCEPTIONS There is ample evidence in the educational literature that student misconceptions of information will inhibit the learning of concepts related to the misinformation. The following concepts covered in Chapter 33 are commonly the subject of student misconceptions. This information on “bioliteracy” was collected from faculty and the science education literature. • Students do not understand the evolution of endosymbionts in animal cells. • Students are unsure that many of the lower animals are classified as animals. • Students think that all animals evolved at about the same time. • Students believe that all animals are mobile. • Students do not understand the relationship between symmetry and lifestyle. • Students do not fully comprehend the location of the coelom in animals. • Students are unsure that many of the lower animals are classified as animals. • Students do not distinguish between colonial and multicellular cell arrangements. • Students believe that all animals have identical organ system structures. • Students do not know the full significance of segmentation. • Students are unaware of the limitations of different types of respiratory systems. • Students are unaware of the limitations of different types of circulatory systems. • Students believe that most animals are vertebrates. • Students believe that animals exclusively reproduce sexually. • Students do not equate humans with being animals. • Students believe that cells of protists and animals are almost identical in structure and function. • Students believe that animal classification is based on one linear line of evolution. • Students believe that all animals have identical organ system structures. • Students are unaware of molecular methods of animal classification. • Students are unaware of molecular methods of animal classification. INSTRUCTIONAL STRATEGY PRESENTATION ASSISTANCE • • Suggest that your students prepare charts indicating how various physiological functions occur in each of the phyla presented in this and the next few chapters. Include nervous activities, reproduction, respiration, digestion, excretion, circulation, and locomotion. This type of chart makes it easier to see the functional and evolutionary relationships among the various phyla. • • Stress that the Cnidarian life cycle is NOT an alternation of generations. Although the medusa generally produces gametes, both the polyp and the medusa are diploid organisms. They are not analogous to sporophyte and gametophyte! HIGHER LEVEL ASSESSMENT Higher level assessment measures a student’s ability to use terms and concepts learned from the lecture and the textbook. A complete understanding of biology content provides students with the tools to synthesize new hypotheses and knowledge using the facts they have learned. The following table provides examples of assessing a student’s ability to apply, analyze, synthesize, and evaluate information from Chapter 33. Application • Have students describe the value of a psuedocoelom over the acoelomate condition. • Have students explain value of segmentation in the evolution of different types of mobility. • Have students describe similarities and differences between the metabolic needs of animals and plants. • Have students explain if mobility is a necessary criterion for categorizing an organism as an animal. • Ask students to explain the benefits and negative aspects of bilateral symmetry. • Ask students to explain the benefits and negative impacts of segment specialization. Analysis • Have students describe the pros and cons of using anatomical features to classify animals. • Have students debate whether highly conserved DNA or highly variable DNA is best for distinguishing differences between two species of animals within the same genus. • Have students explain the probable lifestyle of a fossil platyheminthes that appears to have evolved radial symmetry. • Have students compare and contrast the segmentation specialization of annelids and arthropods. • Ask students to explain the evidence supporting that metazoans were derived from colonial protists. • Have a student explain the benefits of an animal that has mobile larvae and immobile adult forms. Synthesis • Have students find an agricultural application for a chemical that regulates segmentation genes in animals. • Ask the students to find a medical application that exploits indeterminate development in deuterostome embryos. • Ask the students to find a medical application that exploits the knowledge of shell secretion in mollusks. Evaluation • Ask students evaluate the effectiveness of a medical treatment that “starves” tapeworms. • Ask students evaluate the benefits and risks of using research animals to study human disease. • Ask students to evaluate the strategy of eradicating snails as a method of controlling the spread of trematodes. • Ask students to evaluate the accuracy of studying echinoderm embryos as a way of better understanding human development. • Ask students to evaluate the effectiveness and safety of any veterinary treatment used to kill pathogenic worms that live in pets. VISUAL RESOURCES • Have specimens on hand of all phyla—pictures are o.k., but actual specimens of corals, anemones, hydra, sea stars, flatworms, roundworms, segmented worms, and various arthropods are necessary for the student to see the diversity in form between all animals. Most students are not familiar with the appearance of a real sponge, not even a spongin skeleton. They are only familiar with the multicolored “Pseudospongia plastica.” Bring in examples and/or photographs of others, especially finger sponges and freshwater Spongilla. Recommend a trip to a nearby marine aquarium if possible. IN-CLASS CONCEPTUAL DEMONSTRATIONS A. A Remote Demonstration. Introduction Few students realize that researcher modern animal behavior studies are done using remote cameras that can measure animal movement, body temperature, and other physiological parameters. This demonstration permits the class to see live video-cameras animal study in which a series of cameras can be controlled by the instructor. Materials • Computer with Media Player and Internet access • LCD hooked up to computer • Web browser linked to Racerocks.com at http://142.31.86.230/Ex1/. Procedure & Inquiry 1. Ask the class why it is preferable for researchers to study animals in nature and without disturbing the animals. 2. Then explain you want to see a model experiment using videocams to study animal behavior and habitats. 3. Load up the website and click on one of the videocams. 4. Then use the controls to scan the environment and the class to hypothesize the location of the area and any obvious habitats. 5. Then ask the class to determine the animals being studied in the camera views. Also ask them to think about any other animals that can be the subject of study by the cameras. 6. Start the first. 7. Ask the students briefly explain the types of information that can be gathered using the videocams to record the animal. 8. Let the students know that the information is saved in video databases and assessed with statistical that calculates various things going on with the animals. B. Action Images Introduction This demonstration permits the class to see a live video-camera footage of the different organisms discussed in Chapter 34. Materials • Computer with Media Player and Internet access • LCD hooked up to computer • Web browser linked to Racerocks.com at http://www.racerocks.com/racerock/eco/taxalab/taxonomy.htm Procedure & Inquiry 9. Explain to the class that you will be showing them videoclips of the animals covered in Chapter 34. 10. Load up the website and click on the Animal drop-down icon. 11. Then use the cursor to select an organism and show the short video stream. 12. Have the students explain how the organism is characteristic of its phylum and class. 13. Ask the students briefly explain the types of information that can be gathered by watching the videocam recordings. LABORATORY IDEAS A. Brine Shrimp as a Toxicology Model This activity has students design an experiment in which use brine shrimp amoebocytes (white blood cells) as a model of animal toxicology. a. Explain to students how animals and animal cells are used in medicine and research as models for human studies. b. Tell students that they will be investigating the conditions needed for fungal spore germination in two types of fungi. c. Provide students with the following materials a. Large brine shrimp in chilled water b. Microscope c. Microscope slides d. Plastic pipette e. 0.5% Trypan Blue solution in dropper bottle f. Sharp scalpel g. Standard Cytotoxic Solution of household bleach in a dropper h. Test solutions with droppers i. Endotoxins (agar or solution from Gram – bacterial colony) ii. Pesticide iii. 70% Ethanol iv. Sterile water v. Solutions students may request if available d. Instruct students how to collect amoebocytes form the tail of a brine shrimp: a. Place the cooled shrimp on a slide with minimum amount of water b. Carefully slice off the tail at the base of the shrimps body c. Quickly place the shrimp on the microscope and focus on the cut area under medium to high power. d. Add 2 drops of trypan blue. e. Observe the amoebocytes which are small ovoid cells that leak out with the blood. f. Healthy amoebocytes are clear and show some cytoplasmic granules. g. Dying and dead amoebocytes turn blue as they take up the trypan blue. e. Have the students use the bleach as a cytotoxicity control to kill the amoebocytes. This is done by adding on drop of bleach to the cells in the trypan blue while observing the amoebocytes under the microscope. Have them notice how the dying and dead shrimp cells and amoebocytes turn blue. f. Then tell the students to test the other materials and make conclusions about their results. B. Planarian’s with a Buzz This activity asks students to investigate planaria as a model for investigating ciliary activity. g. Explain to students how simple animals and animal cells are used in medicine and research as models for human studies. h. Tell students that they will be investigating the pharmacological effects of certain compounds on the activity of cilia i. Provide students with the following materials a. Live planaria (Dugesia sp) b. Microscope c. Microscope slides d. Glass coverslips e. Plastic pipette f. Test solutions with droppers i. Strong brewed coffee ii. Nicotine solution made from cigarettes soaked in water iii. 10% Ethanol iv. 1% W/V EDTA solution (ethylenediaminetetraacetic acid) v. Solutions students may request if available j. Instruct students build a planarian observation slide using the following steps: a. Carefully crack a glass coverslip into four sections. i. The broken coverslip will be used to build “pillars” to support another coverslip placed on the slide. b. Place a drop of water on the coverslip. c. Place a flatworm in the water. d. Then use the broken coverslip to build a support for another coverslip to be placed over the worm. e. Add the other coverslip and observe the worm under the microscope. k. Have the students observe the rate of ciliary activity of the planarians. l. Encourage the students to calculate the speed at which cilia are beating. m. Then tell the students to test the effects of the various solutions on cilia activity. A separate worm should be used for each treatment. n. Students should be encouraged to seek research references to explain the cellular and molecular mechanisms of cilia excitation or inhibition. C. Comparison of Segmentation This activity asks students to investigate the variation in segmentation between different coelomate invertebrates. a. Review the concept of segmentation to students. b. Tell students that they will be investigating the similarities and differences of segmentation in different coelomate invertebrates. c. However, tell them you want them to first see if there is any evidence of segmentation in the no coelomates such as flatworms. d. Provide students with the following materials a. Planarian slide b. Preserved earthworm c. Preserved clamworm d. Preserved grasshopper e. Preserved chiton f. Microscope e. Instruct students to investigate and describe any evidence segmentation in flatworms f. Then tell the students to explain the similarities and differences in segmentation in the various coelomate invertebrates provided for examination. LEARNING THROUGH SERVICE Service learning is a strategy of teaching, learning and reflective assessment that merges the academic curriculum with meaningful community service. As a teaching methodology, it falls under the category of experiential education. It is a way students can carry out volunteer projects in the community for public agencies, nonprofit agencies, civic groups, charitable organizations, and governmental organizations. It encourages critical thinking and reinforces many of the concepts learned in a course. 1. Have students do a lesson do a hands-on program on the diversity of animals at a nature center. 2. Have students tutor high school students animal diversity. 3. Have students do a lesson do a program “edible insects” for a civic group. 4. Have students volunteer on environmental restoration projects with a local conservation group. 5. Have students volunteer at the educational center of a zoo or marine park. Instructor Manual for Understanding Biology Kenneth Mason, George Johnson, Jonathan Losos, Susan Singer 9780073532295, 9781259592416
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