Five Kingdom System to Unit 3-1 PDF

Unit Two: Characteristics and Classification of Organisms have relatively large and complex cells that contain a nucleus and other membrane-enclosed compartments. They are grouped into the domain Eukarya. The domaineukarya includes groups such protists, fungi, plants and animals. Domain is the rank...

Unit Two: Characteristics and Classification of Organisms have relatively large and complex cells that contain a nucleus and other membrane-enclosed compartments. They are grouped into the domain Eukarya. The domaineukarya includes groups such protists, fungi, plants and animals. Domain is the rank above kingdom. Key Terms Archaea:is a group of single-celled organisms that lack a nucleus but are more closely related to eukaryotes than to bacteria. Bacteria: is the most diverse and well-known group of single-celled organisms that lack a nucleus. Classes: is a taxon of similar orders. Eukaryotic cells: are single-celled organisms with a nucleus. Family: is a taxon of similar genera. Genera: is a taxon of similar species. Kingdoms: is a taxon of similar phyla (plural for phylum). Orders: is a taxon of similar families. Phylum: is a taxon of similar classes. (Plant taxonomists use the taxon division instead of phylum). Prokaryotic cells: are unicellular organisms without a separate nucleus. Species: unique type of organism Taxon: is a group of organisms that share a unique setof traits. Self Assessment 1. What is taxonomic hierarchy? 2. List some of the taxonomic hierarchies Figure 2.2. Taxonomic hierarchy that you know. Grade 9 Biology 23 Unit Two: Characteristics and Classification of Organisms Did You Know? Have you ever asked yourself what a species is? What are the characteristic features of a species? The smallest natural group of organisms is the species. A species can be defined as a group of organisms that can reproduce to produce fertile offspring. Members of a species also often resemble each other very closely in appearance, unless humans have taken a hand in the breeding programs. All cats belong to the same species but there are wide variations in the appearance of different breeds. There are many other definitions of species; for example, phylogenetic species, morphological species, evolutionary species, systematic species, recognition species etc. However, for a biological species, members could reproduce to produce fertile offspring. Members of a species also often resemble each other very closely in appearance. 2.3 Relevance of classification Objectives Activity 2.5: Investigating At the end of this section, the student will be able to: 1. Why and how do describe the relevance of classification human beings classify organisms? What is the relevance of biological classification? 2. Visit a library in your school or public library Classification gives biologists a framework that allows them to study in your village, and write the relationships between living (extant) and extinct organisms. For on the importance of example, this framework allows biologists to study the relationship biological classification and present your results between birds and dinosaurs. Biologists have found that the bones of to your classmates. some dinosaurs have large internal spaces. So do the bones of birds. Because of these findings, some biologists believe that dinosaurs are more closely related to birds than to reptiles. Taxonomy can be a useful tool for scientists who work in such areas as agriculture, forestry, and medicine. Taxonomy can also help the economy. For example, taxonomists can discover new sources of lumber, foods, medicines, and energy. For example, a taxonomist might know that a certain species of tree contains chemicals that make good disinfectants (e.g., Shiferaw/Moringa). It is possible that a closely related plant species could have the same useful substances. So instead of having one source of chemicals, there may be two or more sources. Self Assessment 1. For which of the following purposes could taxonomy be used? a. to determine whether a plant is safe to be planted in a schoolyard b. to find a new source for medicine that comes from plants c. to determine how closely related two species animals d. all of the above 24 Grade 9 Biology  Unit Two: Characteristics and Classification of Organisms 2.4 Linnaean system of nomenclature Objectives Activity 2.6: Inquiring and researching At the end of this section, the student will be able to: Did you know Carl describe the system of Linnaean nomenclature Linnaeus? explain how organisms are given scientific names. List the contribution of Carl write scientific names properly and give examples. Linnaeus to the Science of taxonomy. How did Carl Linnaeus classify living organisms? Linnaeus was a Swedish naturalist who initially graduated in medicine but became interested in plants. He travelled in Scandinavia, England and Eastern Europe, discovering and naming new plant species. In 1735 he published his Systema Naturae, in which he accurately described 7700 plant species and classified them. He further grouped species into genera, genera into classes, and classes into orders. He also classified over 4000 animals, but rather less successfully into mammals, birds, insects and worms. Linnaeus refined and popularized the binomial system of naming organisms, in which the first name represents the genus and the second name the specific epithet. This system is still the official starting point for naming or revising the names of organisms. Binomial nomenclature Species must be named in such a way that the name is recognized all over the world. For example, maize is named Bekkolo in Amharic, Boqqollo in Afan Oromo and Baddelain Sidamu Affo and corn in American English etc. If you are not aware of these names, it could lead to confusion. If the botanical name, Zea mays, is used, however, there is no chance of error. As you all might know our country is endowed with cultural and linguistic diversities and each would have different names for the same species. As a result, it would be difficult for a person to know the names given by the 80 plus ethnolinguistic groups in Ethiopia. Similarly, there are over thousands of languages in the African continent and beyond. Therefore, the Latin form of the name allows it to be used in all over the world irrespective of language barriers. The similarity in size, shape, behavior and colormakes it difficult to differentiate one species from the other. Again, the use of the scientific name avoids such confusion. The binomial system of naming species (introduced by Linnaeus) is an internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and the species. Binomial means ‘two names’; the first name gives the genus and the Grade 9 Biology 25 Unit Two: Characteristics and Classification of Organisms second gives the specific epithet. For example, Enset, false banana, Ensete ventricosum and Banana, Musa acuminate, belong to the same family (Musaceae).In writing a scientific name, the first letter of name of the genus is a capitalized letter and the specific epithet always starts with a small letter, for example, the scientific name of human beings is Homo sapiens. The scientific names are underlined when handwritten or italicized when printed. Self Assessment 1. What is a binomial nomenclature? 2. Write the scientific names of the following organisms: house fly, mouse, dogs, cat & goat. 2.5 Common Ethiopian animals and plants Objectives At the end of this section, the student will be able to: classify common Ethiopian animals and plants based on the taxonomic categories. write the scientific names of common Ethiopian plant and animals species use dichotomous keys to identify unknown organism Ethiopia is endowed with high biological diversity (biodiversity) due to its geographical location, topographical diversity and diverse climatic features. The country is a hot spot for a diversity of wild plant and animal species with a high degree of endemicity. Furthermore, Ethiopia is a primary centre of diversity for field crops such as noug (Guizotia abyssinica), tef (Eragrostis tef) and the Ethiopian mustard (Brassica carinata). Besides, field crops such as barley, sorghum, durum wheat, finger millet, faba bean, chickpea, lentil, and cowpea have wide diversity in Ethiopia. Also Ethiopia has served as a gateway to domestic animals from Asia to Africa and its diverse ecology favoured diversification of these resources. The scientific and common names of some plants and animals in Ethiopia are presented in table 1. Activity 2.7:Inquiring and Researching Read books and/or search in the internet for the scientific and the local names common Ethiopian plants and animals species. Present your report to your classmates. 26 Grade 9 Biology  Unit Two: Characteristics and Classification of Organisms Table 1: Scientific names of some common plants and animals in Ethiopia Common Taxon name Kingdom Phylum/ Class Order Family Genus Species Division Elephant Animalia Chordate Mammalia Proboscidea Elephanti- Loxodonta Loxodonta dae africana Ethiopian Animalia Chordate Mammalia Carivora Canidae Canis Canissimen- Wolf sis Gelada Animalia Chordate Mammalia Primate Cercopith- Thero- Theropithe- ecidae pithecus cus gelada Lion Animalia Chordate Mammalia Carivora Felidae Panthera Panthera leo Walia Animalia Chordate Mammalia Artiodactyla Bovida Capra Capra walie Ostrich Animalia Chordate Ave Struthioni- Struthion- Struthio Struthio formes idae camelus Watled Animalia Chordate Ave Pelecani- Threskior- Bostrychia Bostrychia Ibis formes nithidae carunculata Enset Plantae Angio- Monocy- Zingiberales Mussaseae Ensete Ensete ven- spermata lodoneae tricosum Maize Plantae Angio- Lilospida Cyperales Poacea Zea Zea mays spermata Noug Plantae Angio- Eudicots Asterales Asteraceae Guizotia Guizotia spermata abyssinica Tef Plantae Angio- Lilospida Cyperales Poacea Eragrotes Eragrstos tef spermata Wheat Plantae Angio- Lilospida Cyperales Poacea Triticum Triticum spermata aestivum Dichotomous keys Dichotomous keysare used to identify unfamiliar organisms. They Activity 2.8: Inquiring and simplify the process of identification. Each key is made up of pairs of Researching contrasting features (dichotomous means two branches), starting with You may have come across quite general characteristics and progressing to more specific ones. organisms that you did not By following the key and making appropriate choices it is possible recognize and could not to identify the organism correctly. Figure 2.3 shows an example of a classify. How do you solve dichotomous key that could be used to place an unknown vertebrate this problem? and unknown invertebrate in the correct class. Item 1 gives you a choice between two alternatives. If the animal is poikilothermic (cold-blooded), you move to item 2 and make a further choice. If it is a homoiothermic (warm-blooded), you move to item 4 for your next choice. The same technique may be used for assigning an organism to its class, genus or species. However, the important features may not always be easy to see and you have to make use of less fundamental characteristics. Grade 9 Biology 27 Unit Two: Characteristics and Classification of Organisms Figure 2.3. Vertebrate (left) and invertebrate(right) keys 2.6 The five-kingdom system of classification Self Assessment Objectives 1. Make a field visit in At the end of this section, the student will be able to: your village and or your list the characteristic feature of the five kingdoms, school compound and describe the kingdoms of the Monera, Protista and Fungi ask the names of twenty and give examples of organisms from each one. common Ethiopian describe the kingdom Plantae and explain its major taxa, animals and plants. giving examples. discuss features the kingdom Animalia and explain its major Write their scientific taxa, giving examples.roup animals into vertebrates and names along with invertebrates and explain the differences between them. their local names. Why did we come up with the five kingdoms? Classification of organisms into plants and animals was easily done and understood, but a large number of organisms did not fall into either category. Hence the two kingdom classification used for a long time was found inadequate. Besides, gross morphology a need was Activity 2.9: Cooperative also felt for including other characteristics like cell structure, nature Learning of cell wall, mode of nutrition, habitat, methods of reproduction, What is the largest group evolutionary relationships, etc. of organisms recognized by biologists? How many such Whittaker (1969) proposed a five kingdom classification to solve groups should there be? the pitfalls of the two kingdom system of classification. The main Most biologists used to favor criteria for classification used by him include cell structure, body the adoption of two groups. organization, mode of nutrition, reproduction and phylogenetic What are these two groups? relationships. Whittaker’s five-kingdom scheme consists of animals, plants, fungi, monera and protists(Fig.2.4). It is still not easy to fit all 28 Grade 9 Biology  Unit Two: Characteristics and Classification of Organisms organisms into the five-kingdom scheme. For example, many protista with chlorophyll (the protophyta) show important resemblances to Did You Know? some members of the algae, but the algae are classified into the plant Viruses are not included kingdom. in any kingdom – they are not considered to be living organisms because they lack key characteristics of living things. Viruses are particles that are not alive. They cause diseases and infections. Viruses are made up of nucleic acids, either DNA or RNA, surrounded by a protein coat. They are smaller than the tiniest bacterium. Most biologists agree that viruses are not alive because they don’t grow, develop, or carry out respiration. All viruses replicate, or make copies of themselves. However, viruses need the help of living cells to copy themselves. In order to copy Figure 2. 4. The five kingdoms of life itself, a virus must enter a living cell. The cell in which Self Assessment a virus replicates is called the host cell. 1. Do you agree or disagree with the classification of algae as a plant? Explain. 2. Do you suggest an alternative category or group for organisms’ such as algae and the likes? Activity 2.10: Debate Debate on why it is difficult for biologists to develop a rigid classification scheme? Do you think the Whittaker’s five-kingdom scheme has solved the classification problems biologists are trying to answer for generations? Procedure: 1. Divide members of your classmates into three groups. 2. Members of group 1 support the idea that Whittaker’s five-kingdom scheme has solved the classification problems. 3. Members of group 2 are against the idea that Whittaker’s five-kingdom scheme has solved the classification problems. 4. The third group will be the audience. 5. Let members of group 1 and 2 present their position each in five minutes, and 6. Let students from group three ask questions both groups. Grade 9 Biology 29 Unit Two: Characteristics and Classification of Organisms Activity 2.11: Collaborative Kingdom Monera Learning Objectives What do you think about At the end of this section, the student will be able to: when you hear the word bacteria? You probably think describe the kingdom Monera and give example of organisms about germs or something describe importance of Monera that is bad for you. Did you What are Monera? know that some bacteria are actually helpful? For Monera includes eubacteria and archaebacteria. Eubacteria (bacteria) example, some bacteria have strong cell walls. They exist in various shapes and forms (Figs help with human digestion, 2.5 and2.6). Some eubacteria are heterotrophs; otherscan make their while other bacteria help (autotrophs). Some autotrophic bacteria make their own food the way produce cheese, yogurt, and plants do; they are photosynthetic. Others make energy by chemical sourdough bread. However, other bacteria cause diseases reactions; chemosynthetic. The eubacteria live in most habitats, in humans, for example except the most extreme. Some eubacteria cause diseases, like strep Mycobacterium tuberculosis, throat and pneumonia. Most eubacteria, however, are harmless and causes tuberculosis, and helpful. Haemophilus ducreyi, chancroid. Discuss the major distinguishing features of kingdom Monera Key Terms Figure 2.5. Examples major groups of Monera Archaebacteria: methanogen, thermophiles, Archaebacteria (Archaea) have very different cell walls than acidophilic bacteria bacteria,ut like bacteria, archaebacteria make their own food. They are Chemosynthetic: synthesis chemosynthetic and photosynthetic. Archaebacteria live in extreme food using chemical environments. They live in such places as swamps, deep-ocean hot- reaction. water vents and seawater evaporating ponds. The environments in Eubacteria: true bacteria which the archaebacteria live often have no oxygen (Fig 2.5). Figure 2.6. Some representative of taxa of kingdom monera 30 Grade 9 Biology  Unit Two: Characteristics and Classification of Organisms Activity 2.12: Collaborative Did You Know? Learning Most people tend to think of bacteria in terms of illness and disease. Classify the following However, there are actually only a few disease-causing bacteria statements into useful compared to the number of harmless and beneficial bacteria. In versus harmful relating to fact, we could not survive without bacteria. Bacteria cause diseases the importance of bacteria: in plants, animals, and humans. Disease causing bacteria enter the endospores germinate in human body through openings such as the mouth. Bacteria are human lungs, cause infection carried in air, food, and water. Sometimes bacteria enter the body in humans, provide nitrogen through skin wounds. There are two ways bacterial diseases harm in a usable form for plants, people. First, the growth of bacteria can interfere with the normal flavor food, oxygen is a function of body tissues. Second, the bacteria can release a toxin that byproduct of making food directly attacks the host. and Create toxins. Self Assessment If someone tells you that bacteria are bad, how would you respond? Kingdom Protista Objectives At the end of this section, the student will be able to: describe the kingdom Protista and give examples of organisms describe importance of Protista Activity 2.12: Collaborative What are protists? Learning You have learned that all There is no such thing as a typical protist. Kingdom protista contains life is organized into five the most diverse organisms of all the kingdoms (Figs. 2.7 and 2.8). kingdoms. Without using There are single-celled (unicellular) protists as well as many-celled your notes, name all five (multicellular) protists. Some are microscopic, others are very large. kingdoms. Some of the Some can make their own food, some cannot. Protists have only organisms you will learn one thing in common—they are all eukaryotes. That means most of about in this section are their metabolic processes (chemical reactions) take place inside their plantlike, and some are animal-like. Still others have membrane-bound organelles. Other than that, organisms classified characteristics like fungi. as protists are quite different from each other. Some protists, called Some of them were placed protozoans, seem to be like animals except that they only have one in different kingdoms before cell. Others, called algae, seem to be like plants except they do not they were finally classified have roots, stems, or leaves. Algae are photosynthetic and autotrophic. as Kingdom Protista. As you Unicellular algae are the basis of aquatic food chains and produce read this sub-section keep much of the oxygen in Earth’s atmosphere. Still, other protists seem to in mind how much variety there is in the world of be like fungi except that they do not have the same kind of cell walls Protista. that fungi have. Grade 9 Biology 31 Unit Two: Characteristics and Classification of Organisms Figure 2.7. Examples major groups of protists Figure 2.8. Some representative taxa of kingdom Protista Self Assessment Activity 2.14: Reflective discussion 1. What are the You probably come into contact with algae every day. Diatoms are a characteristic features of type of algae whose remains become a powdery, porous rock called protists? diatomite. Diatomite is highly absorbent. It is used in pet litter and to clean up chemical spills. It also is used as an abrasive in household 2. Write the single cleaners. It is even added to paint to add sparkle. Now that you know common feature to all that diatomite is absorbent, sparkling, and abrasive, see if you can protists. imagine some additional uses for it. Discuss the additional application and present to your classmate. 32 Grade 9 Biology  Unit Two: Characteristics and Classification of Organisms Kingdom Fungi Objectives At the end of this section, the student will be able to: describe the kingdom fungi and give example of organisms describe the importance of fungi What are fungi? Fungi are eukaryotic organisms that include microorganisms such as Activity 2.15: Peer yeasts, moulds and mushrooms. conferencing So far, you have studied Except for unicellular yeasts, fungi are filamentous multicellular bacteria, and protists. In organisms. this section, you will learn about the kingdom Fungi. Their bodies consist of long, slender thread-like structures called Fungus is the singular of hyphae. Hyphae play an important role in how they obtain food. fungi. Mushrooms are types of fungi. Think about places Fungi possess a cell wall that is made up of chitin and polysaccharides. you have seen mushrooms Like animals, fungi are heterotrophic in nutrition. But unlike animals, growing. What do those fungi do not ingest (eat) their food. Instead, a fungus absorbs nutrients places have in common? Were they hot, dry, cool, or from the environment outside of its body. Many fungi accomplish damp? Did the mushrooms this task by secreting powerful enzymes into their surroundings, appear suddenly or grow digest compounds from a wide range of sources, living or dead. slowly over time? These enzymes break down complex molecules into smaller organic compounds that the fungi can absorb into their bodies and use (Figs 2.9 and 2.10). Figure 2.9. Examples of fungi Most fungi absorb soluble organic matter from dead substrates and hence are called saprophytes (decomposers). Decomposer fungi break down and absorb nutrients from nonliving organic material, such as fallen logs, animal corpses, and the wastes of living organisms. Grade 9 Biology 33 Unit Two: Characteristics and Classification of Organisms Fungi cannot make their own food. They are heterotrophs. Fungi use Key Terms a process called extracellular digestion to obtain nutrients. This means Mutualism: symbiotic food is digested outside a fungus’s cells and then the digested food relationship in which is absorbed. For example, some hyphae of a fungus will grow into both species benefit. an orange. They release digestive enzymes into the orange that break down the large organic molecules into smaller molecules. These small Parasitism: symbiotic molecules are absorbed into the hyphae and move into the flowing relationship in which cytoplasm. one organism benefits at the expense of another. Fungi can also live with different living as parasites or mutualists. Parasitic fungi absorb nutrients from the cells of living hosts. Some Symbiosis: permanent, parasitic fungi are pathogenic, causing diseases in humans (Example: close association between Candida albicans cause rush and Tinea pedis cause athlete’s foot), two or more organisms animals and plants. Mutualistic fungi also absorb nutrients from a of different species. host organism, but they reciprocate with actions that benefit the host. For example, mutualistic fungi that live inside certain termite species use their enzymes to break down wood, making food available for termites. Fungi can also live as symbionts in association with algae as lichens and with roots of higher plants as mycorrhiza. Fungi can reproduce either by vegetative means (fragmentation, Did You Know? fission and budding), asexual reproduction through spores formation and sexually. The various spores are produced in distinct structures Some fungi cause food called fruiting bodies to spoil, others cause diseases, and some are Yeast (saccharomyces service) is a very important fungus used for even poisonous. However, making injera rise and allows us to make alcohol (Tej, Tella, Beer etc). fungi are important and beneficial. Without fungi, the world would be overrun with huge amounts of waste, dead organisms, and dead plants. Thanks to many fungi, some bacteria, and protists, the organic material is broken down and recycled into the raw materials that other living organisms need. Self Assessment 1. What are the characteristic features of fungi? Figure 2.10.Some representative taxa of kingdom fungi 34 Grade 9 Biology  Unit Two: Characteristics and Classification of Organisms Kingdom Plantae Objectives At the end of this section, the student will be able to: describe the kingdom Plantae and give example of organisms describe characteristic features of major divisions of plants give examples of flowering plants What are plants? Kingdom Plantae includes all eukaryotic, and multicellular Activity 2.16: Reflective autotrophic organisms. Discussion Think of all the things Plants make their own food through the process of photosynthesis. that plants provide for us. Plants have chloroplast and chlorophyll pigment, which is required They are an important for photosynthesis. Photosynthesis also provides oxygen in the source of food. They also atmosphere. provide oxygen through photosynthesis. Some plants They do not move from place to place; they are stationary. are valuable sources of Their cells contain a rigid cell wall made up of cellulose. medicine. What are some other things that plants They reproduce asexually by vegetative propagation or sexually. provide? There are over 250 000 species of plants. These include flowering plants, mosses, ferns, and coniferous plants (see figs2.11 and 2.12). Activity 2.17: Inquiring and Researching Name or think of at least five different plants. You might think of flowers, bushes, shrubs, ferns, trees, and grasses to name a few. They are all plants, yet they look different from each other. As in the other kingdoms you have studied, the plant kingdom has divisions based on shared characteristics. If you were to place plants in divisions, Figure2.11. Examples major groups of plants what characteristics would you use? Hint: Look at figure 2.12 to find useful features to classify plants. Self Assessment 1. What are the characteristic features of plants? Grade 9 Biology 35 Unit Two: Characteristics and Classification of Organisms Figure 2.12. Classification of the plant kingdom Activity 2.18: Interviewing Key Terms Ask a botanist about the Angiosperms: Most diverse seed plant group. Only group that economic, medicinal and makes flowers and fruits. ecological uses of plants Bryophyte: is the common name for three lineages of plants: (e.g., food, medicinal, mosses, liverworts, and hornworts. ornamental, horticultural, Dicots: Most diverse groups of angiosperms; members have two cultural, spiritual, aesthetic, seed leaves, branching leaf veins. music and arts etc.). Embryophyta: land plants; photosynthetic species that protect and nourish the embryo on the parental body Gymnosperm: Seed plant that does not make flowers or fruits; for example, a conifer. Monocots: Highly diverse angiosperm group; includes plants such as grasses that have one seed leaf and parallel veins. Seed plant (spermatophyte): Plant that produces seeds and pollen; an angiosperm or gymnosperm. Vascular plant: Plant having specialized tissues (xylem and phloem) that transport water and sugar within the plant body. Kingdom Animalia Activity 2.19: Investigating Objectives Think about all the animals At the end of this section, the student will be able to: you are familiar with. They list the characteristic feature of the animal kingdom, may be pets, animals in describe characteristic features of invertebrates and nature, or captive animals vertebrates such as in a circus or zoo. list the common class of animals This section explains what all animals have in common. What is an Animal? List the characteristics you know about that all animals Kingdom Animalia includes all multicellular, heterotrophic, share. eukaryotic animals. Constructing a good definition of an animal is 36 Grade 9 Biology  Unit Two: Characteristics and Classification of Organisms not straightforward, as there are exceptions to nearly every criterion for distinguishing animals from other life forms. However, several characteristics of animals, when taken together, sufficiently define them. Animals differ from both plants and fungi in their mode of nutrition. Unlike plants, animals are not photosynthetic. Animals consume food obtained from other organisms (i.e. they are heterotrophs). But unlike fungi, most animals do not feed by absorption; instead, animals ingest their food and then use enzymes to digest it within their bodies. In contrast to plants and fungi, however, animals lack the structural support of cell walls. Instead, animal cells are held together by structural proteins, the most abundant being collagen, which is found only in animals. Many animals have two types of specialized cells not seen in other multicellular organisms: muscle cells and nerve cells. In most animals, these cells are organized into muscle tissue and nervous tissue, respectively, and are responsible for moving the body and conducting nerve impulses. The ability to move and conduct nerve impulses underlies many of the adaptations that differentiate animals from plants and fungi, making muscle and nerve cells central to what it means to be an animal. Most animals reproduce sexually. Animals are very diverse. They are generally classified into two groups based on the presence or absence of backbone as invertebrates (animals with no backbone) and vertebrates (animals with a backbone(Fig. 2.13 -2.15). Figure 2.13. Major groups of animals Grade 9 Biology 37 Unit Two: Characteristics and Classification of Organisms Self Assessment Activity 2.20: Collaborative Learning Groups 1. What are the What are the two largest groups of animals recognized by biologists/ characteristic features of zoologists? Figure Makegroups 2.13. Major a fieldofvisit in your school compound or village animals animals? and try to classify the animals you see/know into invertebrates or 2. What are the differences vertebrates. (Hint: you could use a dichotomous key) between invertebrate and vertebrates? Figure 2.14. Major groups of invertebrates Key Terms Anatomy: the study of internal structure, as revealed by dissection. Invertebrates: are animals without a backbone. Morphology: is the study of the form or outward appearance of organisms. Vertebrates: are animals with a backbone. Activity 2.21: Interviewing Make internet search or ask a biologist about medically or agriculturally important insects (e.g., grasshopper, tsetse fly, mosquito, honey bee etc.) and list their importance (Hint: economic, pollination, pest, aesthetic; music and arts, cultural, spiritual, vector etc.). 38 Grade 9 Biology