Diversity in Living Organisms PDF

For more FREE DOWNLOADS, visit www.aspirationsinstitute.com C hapter 7 DIVERSITY IN LIVING ORGANISMS Have you ever thought of the multitude of for thousands of years while insects like...

For more FREE DOWNLOADS, visit www.aspirationsinstitute.com C hapter 7 DIVERSITY IN LIVING ORGANISMS Have you ever thought of the multitude of for thousands of years while insects like d life-forms that surround us? Each organism mosquitoes die within a few days. Life also is different from all others to a lesser or ranges from colourless or even transparent he greater extent. For instance, consider yourself worms to brightly coloured birds and flowers. and a friend. This bewildering variety of life around us Are you both of the same height? has evolved on the earth over millions of Does your nose look exactly like your years. However, we do not have more than a friend’s nose? tiny fraction of this time to try and is Is your hand-span the same as your understand all these living organisms, so we friend’s? cannot look at them one by one. Instead, we However, if we were to compare ourselves look for similarities among the organisms, bl and our friends with a monkey, what would which will allow us to put them into different we say? Obviously, we and our friends have classes and then study different classes or a lot in common when we compare ourselves groups as a whole. pu with a monkey. But suppose we were to add In order to make relevant groups to study a cow to the comparison? We would then the variety of life forms, we need to decide think that the monkey has a lot more in which characteristics decide more be T common with us than with the cow. fundamental differences among organisms. re Activity ______________ 7.1 This would create the main broad groups of o R organisms. Within these groups, smaller sub- We have heard of ‘desi’ cows and Jersey groups will be decided by less important cows. characteristics. Q tt E Does a desi cow look like a Jersey cow? Do all desi cows look alike? Will we be able to identify a Jersey cow uestions C in a crowd of desi cows that don’t look 1. Why do we classify organisms? like each other? 2. Give three examples of the range What is the basis of our identification? of variations that you see in life- no N In this activity, we had to decide which forms around you. characteristics were more important in forming the desired category. Hence, we were also deciding which characteristics could be © ignored. Now, think of all the different forms in 7.1 What is the Basis of which life occurs on earth. On one hand we Classification? have microscopic bacteria of a few micrometre in size. While on the other hand we have blue Attempts at classifying living things into whale and red wood trees of california groups have been made since time of approximate sizes of 30 metres and immemorial. Greek thinker Aristotle classified 100 metres respectively. Some pine trees live animals according to whether they lived on For more FREE DOWNLOADS, visit www.aspirationsinstitute.com land, in water or in the air. This is a very this way, we can build up a whole hierarchy simple way of looking at life, but misleading of mutually related characteristics to be used too. For example, animals that live in the sea for classification. include corals, whales, octopuses, starfish Now-a-days, we look at many inter-related and sharks. We can immediately see that characteristics starting from the nature of the these are very different from each other in cell in order to classify all living organisms. numerous ways. In fact, their habitat is the What are some concrete examples of such only point they share in common. This is not characteristics used for a hierarchical an appropriate way of making groups of classification? organisms to study and think about. A eukaryotic cell has membrane-bound We therefore need to decide which organelles, including a nucleus, which d characteristics to be used as the basis for allow cellular processes to be carried out making the broadest divisions. Then we will efficiently in isolation from each other. he have to pick the next set of characteristics Therefore, organisms which do not have for making sub-groups within these divisions. a clearly demarcated nucleus and other This process of classification within each organelles would need to have their group can then continue using new biochemical pathways organised in very characteristics each time. is different ways. This would have an effect Before we go on, we need to think about on every aspect of cell design. Further, what is meant by ‘characteristics’. When we nucleated cells would have the capacity are trying to classify a diverse group of bl to participate in making a multicellular organisms, we need to find ways in which organism because they can take up some of them are similar enough to be specialised functions. Therefore, this is thought of together. These ‘ways’, in fact, are pu details of appearance or behaviour, in other a basic characteristic of classification. words, form and function. Do the cells occur singly or are they What we mean by a characteristic is a grouped together and do they live as an be T particular form or a particular function. That indivisible group? Cells that group together to form a single organism use re most of us have five fingers on each hand is the principle of division of labour. In such o R thus a characteristic. That we can run, but the banyan tree cannot, is also a a body design, all cells would not be characteristic. identical. Instead, groups of cells will tt E Now, to understand how some carry out specialised functions. This characteristics are decided as being more makes a very basic distinction in the fundamental than others, let us consider how body designs of organisms. As a result, C a stone wall is built. The stones used will have an Amoeba and a worm are very different different shapes and sizes. The stones at the in their body design. top of the wall would not influence the choice Do organisms produce their own food no N of stones that come below them. On the other through the process of photosynthesis? hand, the shapes and sizes of stones in the Being able to produce one’s own food lowermost layer will decide the shape and size versus having to get food from outside of the next layer and so on. would make very different body designs © The stones in the lowermost layer are like necessary. the characteristics that decide the broadest Of the organisms that perform divisions among living organisms. They are photosynthesis (plants), what is the level independent of any other characteristics in of organisation of their body? their effects on the form and function of the Of the animals, how does the individual’s organism. The characteristics in the next level body develop and organise its different would be dependent on the previous one and parts, and what are the specialised would decide the variety in the next level. In organs found for different functions? D IVERSITY IN LIVING ORGANISMS 81 For more FREE DOWNLOADS, visit www.aspirationsinstitute.com We can see that, even in these few questions When we connect this idea of evolution to that we have asked, a hierarchy is developing. classification, we will find some groups of The characteristics of body design used for organisms which have ancient body designs classification of plants will be very different that have not changed very much. We will from those important for classifying animals. also find other groups of organisms that have This is because the basic designs are different, acquired their particular body designs based on the need to make their own food relatively recently. Those in the first group (plants), or acquire it (animals). Therefore, are frequently referred to as ‘primitive’ or ‘lower’ these design features (having a skeleton, for organisms, while those in the second group example) are to be used to make sub-groups, are called ‘advanced’ or ‘higher’ organisms. In rather than making broad groups. reality, these terms are not quite correct since Q d they do not properly relate to the differences. uestions All that we can say is that some are ‘older’ he organisms, while some are ‘younger’ 1. Which do you think is a more basic organisms. Since there is a possibility that characteristic for classifying complexity in design will increase over organisms? evolutionary time, it may not be wrong to say (a) the place where they live. that older organisms are simpler, while is (b) the kind of cells they are younger organisms are more complex. made of. Why? 2. What is the primary characteristic Biodiversity means the diversity of life bl on which the first division of organisms is made? forms. It is a word commonly used to 3. On what bases are plants and refer to the variety of life forms found in a particular region. Diverse life forms pu animals put into different categories? share the environment, and are affected by each other too. As a result, 7.2 Classification and Evolution a stable community of different species be T comes into existence. Humans have re All living things are identified and categorised played their own part in recent times o R on the basis of their body design in form and in changing the balance of such function. Some characteristics are likely to communities. Of course, the diversity make more wide-ranging changes in body in such communities is affected by More to know tt E design than others. There is a role of time in particular characteristics of land, this as well. So, once a certain body design water, climate and so on. Rough comes into existence, it will shape the effects estimates state that there are about ten C of all other subsequent design changes, million species on the planet, although simply because it already exists. In other we actually know only one or two words, characteristics that came into no N millions of them. The warm and humid existence earlier are likely to be more basic tropical regions of the earth, between than characteristics that have come into the tropic of Cancer and the tropic of existence later. Capricorn, are rich in diversity of plant This means that the classification of life and animal life. This is called the region © forms will be closely related to their evolution. of megadiversity. Of the biodiversity What is evolution? Most life forms that we of the planet, more than half is see today have arisen by an accumulation of concentrated in a few countries – changes in body design that allow the Brazil, Colombia, Ecuador, Peru, organism possessing them to survive better. Mexico, Zaire, Madagascar, Charles Darwin first described this idea of Australia, China, India, Indonesia and evolution in 1859 in his book, The Origin of Malaysia. Species. 82 SCIENCE For more FREE DOWNLOADS, visit www.aspirationsinstitute.com Q uestions 7.3.1 MONERA 1. Which organisms are called These organisms do not have a defined primitive and how are they nucleus or organelles, nor do any of them different from the so-called show multi-cellular body designs. On the advanced organisms? other hand, they show diversity based on 2. Will advanced organisms be the many other characteristics. Some of them same as complex organisms? have cell walls while some do not. Of course, Why? having or not having a cell wall has very different effects on body design here from 7.3 The Hierarchy of Classification- having or not having a cell wall in multi- d cellular organisms. The mode of nutrition of Groups organisms in this group can be either by he synthesising their own food (autotrophic) or Biologists, such as Ernst Haeckel (1894), getting it from the environment Robert Whittaker (1959) and Carl Woese (heterotrophic). This group includes bacteria, (1977) have tried to classify all living blue-green algae or cyanobacteria, and organisms into broad categories, called mycoplasma. Some examples are shown is kingdoms. The classification Whittaker in Fig. 7.1. proposed has five kingdoms: Monera, Protista, Fungi, Plantae and Animalia, and bl is widely used. These groups are formed on the basis of their cell structure, mode and source of nutrition and body organisation. pu The modification Woese introduced by dividing the Monera into Archaebacteria (or Resting be T Archaea) and Eubacteria (or Bacteria) is also spore in use. re Further classification is done by naming o R Bacteria the sub-groups at various levels as given in the following scheme: tt E Kingdom Phylum (for animals) / Division (for plants) Heterocyst Class C Order Anabaena Family Genus no N Species Fig. 7.1: Monera Thus, by separating organisms on the basis of a hierarchy of characteristics into 7.3.2 PROTISTA © smaller and smaller groups, we arrive at the This group includes many kinds of unicellular basic unit of classification, which is a eukaryotic organisms. Some of these ‘species’. So what organisms can be said to organisms use appendages, such as hair-like belong to the same species? Broadly, a species cilia or whip-like flagella for moving around. includes all organisms that are similar Their mode of nutrition can be autotrophic enough to breed and perpetuate. or heterotrophic. Examples are unicellular The important characteristics of the five algae, diatoms and protozoans (see Fig. 7.2 kingdoms of Whittaker are as follows: for examples). D IVERSITY IN LIVING ORGANISMS 83 For more FREE DOWNLOADS, visit www.aspirationsinstitute.com to become multicellular organisms at certain Water vacuole stages in their lives. They have cell-walls made of a tough complex sugar called chitin. Cilia Examples are yeast and mushrooms (see Fig. 7.3 for examples). Macronucleus Micronucleus Oral groove Cytosome Food vacuole Cytopyge d Waste he Paramecium Ectoplasm Endoplasm Mitochondria Penicillium Agaricus is Nucleus Aspergillus Crystals bl Food vacuole Fig. 7.3: Fungi Advancing pseudopod Some fungal species live in permanent pu Contractile vacuole mutually dependent relationships with blue- green algae (or cyanobacteria). Such Amoeba relationships are called symbiotic. These be T symbiobic life forms are called lichens. We re have all seen lichens as the slow-growing o R Flagellum (short) large coloured patches on the bark of trees. Eyespot Flagellum (long) 7.3.4 PLANTAE tt E These are multicellular eukaryotes with cell walls. They are autotrophs and use C Photoreceptor Contractile chlorophyll for photosynthesis. Thus, all vacuole Chloroplast Nucleus plants are included in this group. Since no N Nucleolus plants and animals are most visible forms of the diversity of life around us, we will look Euglena at the subgroups in this category later (section 7.4). Fig. 7.2: Protozoa © 7.3.5 ANIMALIA 7.3.3 FUNGI These include all organisms which are These are heterotrophic eukaryotic multicellular eukaryotes without cell walls. organisms. They use decaying organic They are heterotrophs. Again, we will look material as food and are therefore called at their subgroups a little later in saprophytes. Many of them have the capacity section 7.5. 84 SCIENCE For more FREE DOWNLOADS, visit www.aspirationsinstitute.com d he is bl pu be T re o R Fig. 7.4: The Five Kingdom classification Q tt E uestions 7.4 Plantae C 1. What is the criterion for The first level of classification among plants classification of organisms as depends on whether the plant body has well- belonging to kingdom Monera or differentiated, distinct components. The next no N Protista? level of classification is based on whether the 2. In which kingdom will you place differentiated plant body has special tissues an organism which is single- for the transport of water and other celled, eukaryotic and substances within it. Further classification © photosynthetic? looks at the ability to bear seeds and whether 3. In the hierarchy of classification, the seeds are enclosed within fruits. which grouping will have the smallest number of organisms 7.4.1 T HALLOPHYTA with a maximum of characteristics in common and Plants that do not have well-differentiated which will have the largest body design fall in this group. The plants in number of organisms? this group are commonly called algae. These D IVERSITY IN LIVING ORGANISMS 85 For more FREE DOWNLOADS, visit www.aspirationsinstitute.com plants are predominantly aquatic. Examples 7.4.2 BRYOPHYTA are Spirogyra, Ulothrix, Cladophora and Chara (see Fig. 7.5). These are called the amphibians of the plant kingdom. The plant body is commonly differentiated to form stem and leaf-like structures. However, there is no specialised tissue for the conduction of water and other substances from one part of the plant body to another. Examples are moss (Funaria) and Marchantia (see Fig. 7.6). d he Cladophora Ulothrix is Cell-wall bl Chloroplast Riccia Pyrenoids Nucleus pu Cytoplasm be T re o R Ulva Marchantia Funaria Spirogyra tt E Fig. 7.6: Some common bryophytes C 7.4.3 PTERIDOPHYTA In this group, the plant body is differentiated no N into roots, stem and leaves and has specialised tissue for the conduction of water and other substances from one part of the plant body to another. Some examples are © Marsilea, ferns and horse-tails (see Fig. 7.7). The thallophytes, the bryophytes and the pteridophytes have naked embryos that are called spores. The reproductive organs of plants in all these three groups are very Chara inconspicuous, and they are therefore called ‘cryptogamae’, or ‘those with hidden Fig. 7.5: Thallophyta – Algae reproductive organs’. 86 SCIENCE For more FREE DOWNLOADS, visit www.aspirationsinstitute.com 7.4.5 ANGIOSPERMS Leaf This word is made from two Greek words: angio means covered and sperma– means seed. The seeds develop inside an organ which is modified to become a fruit. These are also Sporocarp called flowering plants. Plant embryos in seeds have structures called cotyledons. Cotyledons are called ‘seed leaves’ because Stem in many instances they emerge and become Root green when the seed germinates. Thus, d cotyledons represent a bit of pre-designed Marsilea Fern plant in the seed. The angiosperms are he Fig. 7.7: Pteridophyta divided into two groups on the basis of the number of cotyledons present in the seed. On the other hand, plants with well- Plants with seeds having a single cotyledon differentiated reproductive tissues that are called monocotyledonous or monocots. ultimately make seeds are called Plants with seeds having two cotyledons are is phanerogams. Seeds are the result of the called dicots (see Figs. 7.9 and 7.10). reproductive process. They consist of the embryo along with stored food, which serves bl for the initial growth of the embryo during germination. This group is further classified, based on whether the seeds are naked or pu enclosed in fruits, giving us two groups: gymnosperms and angiosperms. be T 7.4.4 GYMNOSPERMS re o R This term is made from two Greek words: gymno– means naked and sperma– means seed. The plants of this group bear naked tt E seeds and are usually perennial, evergreen and woody. Examples are pines and deodar (see Fig. 7.8 for examples). C Fig. 7.9: Monocots – Paphiopedilum no N © Pinus Cycas Fig. 7.8: Gymnosperms Fig. 7.10: Dicots – Ipomoea D IVERSITY IN LIVING ORGANISMS 87 For more FREE DOWNLOADS, visit www.aspirationsinstitute.com d he is bl pu be T re o R tt E Fig. 7.11: Classification of plants C Activity ______________ 7.2 How many petals are found in the flower of these plants? no N Soak seeds of green gram, wheat, Can you write down further maize, peas and tamarind. Once they characteristics of monocots and dicots Q become tender, try to split the seed. Do on the basis of these observations? all the seeds break into two nearly uestions © equal halves? The seeds that do are the dicot seeds and the seeds that don’t are the 1. Which division among plants has monocot seeds. the simplest organisms? Now take a look at the roots, leaves and 2. How are pteridophytes different flowers of these plants. from the phanerogams? Are the roots tap-roots or fibrous? 3. How do gymnosperms and Do the leaves have parallel or reticulate angiosperms differ from each venation? other? 88 SCIENCE For more FREE DOWNLOADS, visit www.aspirationsinstitute.com 7.5 Animalia layers of cells: one makes up cells on the outside of the body, and the other makes the These are organisms which are eukaryotic, inner lining of the body. Some of these species multicellular and heterotrophic. Their cells live in colonies (corals), while others have a do not have cell-walls. Most animals are solitary like–span (Hydra). Jellyfish and sea mobile. anemones are common examples (see They are further classified based on the Fig. 7.13). extent and type of the body design differentiation found. Tentacles Tentacles Stinging cell 7.5.1 PORIFERA d The word Porifera means organisms with holes. These are non-motile animals attached he Mouth to some solid support. There are holes or ‘pores’, all over the body. These lead to a canal system that helps in circulating water Epidermis throughout the body to bring in food and Mesoglea is oxygen. These animals are covered with a Gastrodermis Gastrovascular hard outside layer or skeleton. The body cavity design involves very minimal differentiation Sea anemone bl and division into tissues. They are commonly Foot called sponges, and are mainly found in Hydra marine habitats. Some examples are shown in Fig. 7.12. pu Fig. 7.13: Coelenterata be T 7.5.3 PLATYHELMINTHES re The body of animals in this group is far more o R complexly designed than in the two other groups we have considered so far. The body tt E is bilaterally symmetrical, meaning that the left and the right halves of the body have the Euplectelea Sycon same design. There are three layers of cells C from which differentiated tissues can be made, which is why such animals are called triploblastic. This allows outside and inside no N body linings as well as some organs to be made. There is thus some degree of tissue formation. However, there is no true internal Spongilla body cavity or coelom, in which well- © developed organs can be accommodated. The Fig. 7.12: Porifera body is flattened dorsiventrally, meaning from top to bottom, which is why these animals are called flatworms. They are either free- 7.5.2 COELENTERATA (CNIDARIA) living or parasitic. Some examples are free- These are animals living in water. They show living animals like planarians, or parasitic more body design differentiation. There is a animals like liverflukes (see Fig. 7.14 for cavity in the body. The body is made of two examples). D IVERSITY IN LIVING ORGANISMS 89 For more FREE DOWNLOADS, visit www.aspirationsinstitute.com 7.5.5 ANNELIDA Branched Eyes gastrovascular cavity Annelid animals are also bilaterally Scolex Sucker symmetrical and triploblastic, but in addition Acetabulum Neck they have a true body cavity. This allows true organs to be packaged in the body structure. There is, thus, extensive organ differentiation. Pharynx Mouth This differentiation occurs in a segmental and anus fashion, with the segments lined up one after the other from head to tail. These animals are found in a variety of habitats– fresh water, d Liverfluke Tape worm Planaria marine water as well as land. Earthworms and leeches are familiar examples (see he Fig. 7.16). Fig. 7.14: Platyhelminthes Tentacle 7.5.4 NEMATODA is Palp The nematode body is also bilaterally symmetrical and triploblastic. However, the bl body is cylindrical rather than flattened. There are tissues, but no real organs, although a sort of body cavity or a pseudo- pu Parapodia Genital coelom, is present. These are very familiar papillae as parasitic worms causing diseases, such Anus as the worms causing elephantiasis (filarial be T worms) or the worms in the intestines (roundworm or pinworms). Some examples re Parapodia o R are shown in Fig. 7.15. tt E Nereis Earthworm Leech Female C Fig. 7.16: Annelida no N 7.5.6 ARTHROPODA Male This is probably the largest group of animals. These animals are bilaterally symmetrical and © segmented. There is an open circulatory system, and so the blood does not flow in well- defined blood vessels. The coelomic cavity is blood-filled. They have jointed legs (the word ‘arthropod’ means ‘jointed legs’). Some Wuchereria familiar examples are prawns, butterflies, Ascaris houseflies, spiders, scorpions and crabs (see Fig. 7.15: Nematodes (Aschelminthes) Fig. 7.17). 90 SCIENCE For more FREE DOWNLOADS, visit www.aspirationsinstitute.com 7.5.8 ECHINODERMATA In Greek, echinos means hedgehog, and derma means skin. Thus, these are spiny Aranea(Spider) skinned organisms. These are exclusively Palaemon free-living marine animals. They are (Prawn) Palamnaeus triploblastic and have a coelomic cavity. They (Scorpion) also have a peculiar water-driven tube system that they use for moving around. They have hard calcium carbonate structures that they Butterfly use as a skeleton. Examples are starfish and d sea urchins (see Fig. 7.19). Pariplaneta he (Cockroach) Musca (House fly) Scolopendra (Centipede) is Fig. 7.17: Arthropoda bl 7.5.7 MOLLUSCA Antedon Holothuria In the animals of this group, there is bilateral (feather star) (sea cucumber) pu symmetry. The coelomic cavity is reduced. There is little segmentation. They have an open circulatory system and kidney-like be T organs for excretion. There is a foot that is used for moving around. Examples are snails re o R and mussels (see Fig. 7.18). tt E Echinus (sea urchin) Asterias (star fish) C Fig. 7.19: Echinodermata 7.5.9 PROTOCHORDATA no N These animals are bilaterally symmetrical, Chiton triploblastic and have a coelom. In addition, Octopus they show a new feature of body design, © namely a notochord, at least at some stages during their lives. The notochord is a long rod-like support structure (chord=string) that runs along the back of the animal separating Unio the nervous tissue from the gut. It provides a Pila place for muscles to attach for ease of movement. Protochordates may not have a Fig. 7.18: Mollusca proper notochord present at all stages in their D IVERSITY IN LIVING ORGANISMS 91 For more FREE DOWNLOADS, visit www.aspirationsinstitute.com lives or for the entire length of the animal. 7.5.10 ((ii) PISCES Protochordates are marine animals. Examples are Balanoglossus, Herdmania and These are fish. They are exclusively aquatic Amphioxus (see Fig. 7.20). animals. Their skin is covered with scales/ plates. They obtain oxygen dissolved in water by using gills. The body is streamlined, and a muscular tail is used for movement. They Proboscis are cold-blooded and their hearts have only two chambers, unlike the four that humans Collarette have. They lay eggs. We can think of many Collar kinds of fish, some with skeletons made d entirely of cartilage, such as sharks, and some with a skeleton made of both bone and he Anus Branchial region cartilage, such as tuna or rohu [see examples Gill pores in Figs. 7.21 (a) and 7.21 (b)]. Dorsally Posthepatic curved is region genital wings Middosrsal bl ridge Synchiropus splendidus Caulophyryne jordani Hepatic caeca (Mandarin fish) (Angler fish) Hepatic region pu be T re o R Pterois volitans Fig. 7.20: A Protochordata: Balanoglossus (Lion fish) Eye tt E 7.5.10 V ERTEBRATA Spiracle These animals have a true vertebral column C and internal skeleton, allowing a completely different distribution of muscle attachment points to be used for movement. Pelvic fin no N Vertebrates are bilaterally symmetrical, Dorsal fin Tail triploblastic, coelomic and segmented, with Caudal fin Sting ray complex differentiation of body tissues and Electric ray (Torpedo) organs. All chordates possess the following © Dorsal fin Eye Tail features: (i) have a notochord (ii) have a dorsal nerve cord Mouth Gills Pectoral Pelvic (iii) are triploblastic fin fin (iv) have paired gill pouches Scoliodon (Dog fish) (v) are coelomate. Vertebrates are grouped into five classes. Fig. 7.21 (a): Pisces 92 SCIENCE For more FREE DOWNLOADS, visit www.aspirationsinstitute.com Eye Head iii)) REPTILIA 7.5.10 ((iii iii Nostril Pectoral These animals are cold-blooded, have scales Mouth fin and breathe through lungs. While most of Caudal Pelvic Pectoral Mouth Dorsal them have a three-chambered heart, fin Brood fin fin crocodiles have four heart chambers. They fin pouch Tail lay eggs with tough coverings and do not need Labeo rohita (Rohu) Male Hippocampus to lay their eggs in water, unlike amphibians. (Sea horse) Snakes, turtles, lizards and crocodiles fall in Wing like pectoral this category (see Fig. 7.23). d he Scales Tail Pelvic fin Exocoetus (Flying fish) Turtle is Chameleon bl Anabas (Climbing perch) pu Fig. 7.21 (b): Pisces 7.5.10 ((ii ii ii)) AMPHIBIA be T These animals differ from the fish in the lack re of scales, in having mucus glands in the skin, King Cobra o R and a three-chambered heart. Respiration is through either gills or lungs. They lay eggs. These animals are found both in water and tt E on land. Frogs, toads and salamanders are some examples (see Fig. 7.22). C House wall lizard no N (Hemidactylus) Flying lizard (Draco) Salamander Toad Fig. 7.23: Reptilia © iv)) AVES 7.5.10 ((iv iv These are warm-blooded animals and have a four-chambered heart. They lay eggs. There Rana tigrina is an outside covering of feathers, and two (Common frog) Hyla (Tree frog) forelimbs are modified for flight. They breathe through lungs. All birds fall in this category Fig. 7.22: Amphibia (see Fig. 7.24 for examples). D IVERSITY IN LIVING ORGANISMS 93 For more FREE DOWNLOADS, visit www.aspirationsinstitute.com Whale White Stork (Ciconia ciconia) Rat Human d Bat Cat he Ostrich (Struthio camelus) Male Tufted Duck (Aythya fuligula) Fig. 7.25: Mammalia Q uestions is 1. How do poriferan animals differ from coelenterate animals? bl 2. How do annelid animals differ from arthropods? 3. What are the differences between pu Sparrow amphibians and reptiles? Pigeon 4. What are the differences between be T animals belonging to the Aves group and those in the mammalia re group? o R Carolus Linnaeus (Karl von Linne) was born in tt E Crow Sweden and was a doctor Fig. 7.24: Aves (birds) by professsion. He was interested in the study of C plants. At the age of 22, 7.5.10 (V) MAMMALIA he published his first no N paper on plants. While Mammals are warm-blooded animals with serving as a personal Carolus Linnaeus four-chambered hearts. They have mammary physician of a wealthy (1707-1778) glands for the production of milk to nourish government official, he studied the their young. Their skin has hairs as well as © diversity of plants in his employer’s sweat and oil glands. Most mammals familiar garden. Later, he published 14 papers and to us produce live young ones. However, a also brought out the famous book few of them, like the platypus and the echidna Systema Naturae from which all lay eggs, and some, like kangaroos give birth fundamental taxonomical researches have to very poorly developed young ones. Some taken off. His system of classification was examples are shown in Fig. 7.25. a simple scheme for arranging plants so The scheme of classification of animals is as to be able to identify them again. shown in Fig. 7.26. 94 SCIENCE For more FREE DOWNLOADS, visit www.aspirationsinstitute.com d he is bl pu be T re o R tt E C no N © Fig. 7.26: Classification of animals D IVERSITY IN LIVING ORGANISMS 95 For more FREE DOWNLOADS, visit www.aspirationsinstitute.com 7.6 Nomenclature which puts it along with the organisms it is most related to. But when we actually name Why is there a need for systematic naming of the species, we do not list out the whole living organisms? hierarchy of groups it belongs to. Instead, we limit ourselves to writing the name of the Activity ______________ 7.3 genus and species of that particular Find out the names of the following organism. The world over, it has been agreed animals and plants in as many that both these names will be used in Latin languages as you can: forms. 1. Tiger 2. Peacock 3. Ant Certain conventions are followed while 4. Neem 5. Lotus 6. Potato d writing the scientific names: As you might be able to appreciate, it 1. The name of the genus begins with a he would be difficult for people speaking or capital letter. writing in different languages to know when 2. The name of the species begins with a they are talking about the same organism. small letter. This problem was resolved by agreeing upon 3. When printed, the scientific name is a ‘scientific’ name for organisms in the same given in italics. is manner that chemical symbols and formulae 4. When written by hand, the genus for various substances are used the world name and the species name have to over. The scientific name for an organism is bl be underlined separately. thus unique and can be used to identify it anywhere in the world. Activity ______________ 7.4 pu The system of scientific naming or Find out the scientific names of any nomenclature we use today was introduced five common animals and plants. Do by Carolus Linnaeus in the eighteenth these names have anything in common be T century. The scientific name of an organism with the names you normally use to is the result of the process of classification identify them? re o R What tt E you have learnt C Classification helps us in exploring the diversity of life forms. no N The major characteristics considered for classifying all organisms into five major kingdoms are: (a) whether they are made of prokaryotic or eukaryotic cells (b) whether the cells are living singly or organised into multi- © cellular and thus complex organisms (c) whether the cells have a cell-wall and whether they prepare their own food. All living organisms are divided on the above bases into five kingdoms, namely Monera, Protista, Fungi, Plantae and Animalia. The classification of life forms is related to their evolution. 96 SCIENCE For more FREE DOWNLOADS, visit www.aspirationsinstitute.com Plantae and Animalia are further divided into subdivisions on the basis of increasing complexity of body organisation. Plants are divided into five groups: Thallophytes, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms. Animals are divided into ten groups: Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata, Protochordata and Vertebrata. The binomial nomenclature makes for a uniform way of identification of the vast diversity of life around us. The binomial nomenclature is made up of two words – a generic d name and a specific name. he Exercises 1. What are the advantages of classifying organisms? is 2. How would you choose between two characteristics to be used for developing a hierarchy in classification? bl 3. Explain the basis for grouping organisms into five kingdoms. 4. What are the major divisions in the Plantae? What is the basis for these divisions? pu 5. How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals? be T 6. Explain how animals in Vertebrata are classified into further subgroups. re o R tt E C no N © D IVERSITY IN LIVING ORGANISMS 97 Source: NCERT