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BIOLOGY / CLASS-IX

CH-4: DIVERSITY IN LIVING WORLD

DIVERSITY IN LIVING WORLD

4.1

INTRODUCTION Diversity is difference in external appearance of living beings in terms of shape, size, colour, nutrition, behaviour etc. The living world is too diverse with an estimate of 5–30 million species. It is impractical to study such a largenumberof species individuallyandthus there is needof classification ofdiversityforthere identification and study of inter-relationship. A good classification makes sure that one has not to study all the organism. One can just study few representative members from a group and that will give him basic idea about all the members belonging to that particular group. Key Terms: Taxonomy: Branch of biology that is concerned with identification, nomenclature and classification of organism. Carolus Linnaeus is the father of taxonomy. Classification:Arrangement of organisms into groups on basis of similarities,difference and relationship.

Knowledge Based Questions 1. Basic unit of classification is (A) Domain (B) Kingdom 2. 3. 4. 5.

(C) Species

(D) None

Concept of Binomial classification was given by (A) Darwin (B) Linnaeus (C) Haeckel

(D) Odum

Which hierarchyhas maximum number of organisms? (A) Order (B) Species (C) Phylum

(D) Class

Virus is (A) Prokaryote

(D) Mesokaryote

(B) Eukaryote

Euglena is (A) Plant (B)Animal (C) Connecting link between plants and animals (D) None of the above

(C) Akaryote

BIOLOGY / CLASS-IX

CH-4: DIVERSITY IN LIVING WORLD

6. 7.

The scientific names are given in language (A) English (B) Hindi

(C) German

In Binomial nomenclature the sequence of name is (A) FamilyGenus (B) Kingdom Phylum (C) Genus species

(D) Latin (D) None of thes

8.

International code of Biological nomenclature (ICBN) is applicable to all living organisms except (A) Plants (B)Animals (C) Bacteria (D) Virus

9.

Five kingdom classification was given by (A) Copeland (B) Whittekar

(C) Woose

(D) None

Humans are (A)Amphibia

(C) Reptilia

(D) None of these

10.

4.2

(B)Aves

DIVERSITY IN THE LIVING WORLD Diversity is the occurrence of the various forms of living beings which differ from one another in external appearance, size, colour, pattern, internal structure, nutrition, behaviour, habitat, etc. Currently, there are 1.7 – 1.8 million organisms. They range in size form microscopic bacteria, hardly a few micrometers in size, to Blue Whale (about 30m in length) and Redwood Trees of California (about 100m in height). Bio diversity is the no. and abundance of species of plants & animals in a habitation, terrestrial or aquatic (fresh water or marine water) within large biosphere. Systematics: It is the study of diversity & kind of organisms and evolutionary relationship between them, it also includes an arrangement of classification and examination of their history and origin. Need for Classification Classification is the arrangement of organisms into groups and subgroups on the basis of their similarities and dissimilarities and placing them in a hierarchy that brings out their relationships. Organisms should be classified because of the following reasons: (i)

We have a limited time to study and understanding all organism by looking them one by one (is impossible). Therefore instead of wasting time by looking them one by one, we can look for the similarities among the organism which will allow it to put them into different classes and then study different classes and group as a whole.

(ii)

When we have groups, we can easily decide which characteristics decide more fundamental difference among the organism. So that within groups we can make smaller sub groups on the basis of their less important characteristics.

(iii)

There is no way to identify organisms without a proper system of classification.

(iv)

Organisms of other localities and fossils can be studied onlythrough a good system of classification.

BIOLOGY / CLASS-IX

CH-4: DIVERSITY IN LIVING WORLD

Try yourself 1.

2.

Classification includes (A) Onlysimilarities

(B) Onlydissimilarities

(C) Both (A) and (B)

(D) None of these

Diversity may be in terms of (A) Shape

3.

(C) Behaviour

(D)All of these

(C) Taxonomy

(D)All of these

Science of classification is (A) Biology

4.

(B) Size (B) Phylogency

Which of following is not included in classification? (A) Phylum

(B) Genus

(C) Species

(D) Ecotype

Importance of Classification (i)

Diversity: It gives an idea of diversity found in living organisms.

(ii)

System of Identification : Classification gives a system for identification of known and unknown organsms.

(iii)

Other Biological Sciences:All biological sciences depend upon a system of classification for studyof organisms, e.g., biogeography,(geographical distribution of plants and animals) ecology (study of inter-relationship between physical environment and living organisms i.e. plants and animals), pathology, forestry. Consider the case of the science of biogeography, which is the study of geographical distribution of plants and animals.

(iv)

Inter-relations: It provides information about interrelationships between different categories of organisms.

(v)

Evolution: Classification based on natural relationships, resemblances and differences provides information as to the origin and evolution of various groups of organisms.

Try yourself 5.

6.

Classification is used for identification of (A) Known organism

(B) Unknown organism

(C) Both (A) and (B)

(D) None of these

Relation between biotic and abiotic factors is studied in (A) Pathology

(B) Forestry

(C) Ecology

(D) Virology

Taxonomy The science dealing with Identification, nomenclature and classification of organisms is called Taxonomy or systematics. Swedish scientist Carolus Linnaeus (1707 – 1778) is called father of taxonomy. He introduced the system of binomial nomenclature (Philosophia Botanica, 1751).

BIOLOGY / CLASS-IX

CH-4: DIVERSITY IN LIVING WORLD

Nomenclature It is system of providingdistinct and proper names to living and nonlivingobjects.. Biological nomenclature is of two types – common and scientific. Common or Vernacular Names: They are names given to organisms by local people in different regions of the world. The residents of an area become familiar. However, common names cannot be used by biologists because of the following defects. Try yourself 7.

Common names are (A) Unscientific

8.

(C) Both (A) and (B)

(D) Easy

(B) Genus

(C) Species

(D) Phylum

(B) Insect

(C) Cnidaria

(D) Mollusca

In Binomial nomenclature last name represents (A) Family

9.

(B) Misleading

Jellyfish is (A) Fish

Disadvantages of Common Names (i)

Unnamed Organisms: Many organisms found in an area do not have common names.

(ii)

Limited Distribution:All organisms do not occur in an area.

(iii)

Same Names:Acommon name is often used for two or more organisms, e.g., Kandiali (Plants having spines), dodhak (plants having milky latex), Kenchua (roundworm, earthworm), chirrya (small sparour - like birds).

(iv)

Misleading Names:Anumber of aquatic animals are called fishes though theyhave no relation with real fish, e.g., Jelly Fish, Cray Fish, Star Fish, Cuttle Fish, Silver Fish

(v)

Multiple Names: A single organism may have several names in the same language, e.g., 8 Hindi names for PricklyPoppy. Onion is Pyaz in Bengali and Hindi, Gundain Punjabi, Vengayam in Tamil, Irulli in Kannada, Dungari in Gujarati and Pareru inAssamese.

The problem was resolved by scientists by agreeing upon universal scientific names in the same manner that they had agreed upon the use of chemical symbols and formulae. Nomenclature is a system of naming plants and animals. The name of every organism is composed of two components – first one genus (generic) and second species name (specific). For example, the scientific name of human species is Homo sapiens, where Homo is a generic name and sapiens a species name.All over the world, Homo sapiens will be understood to mean humans. Because of two components in the name this kind of naming is termed binomial nomenclature. They are guided by a set of rules stated in the International Code of Nomenclature. Binomial nomenclature was proposed by Carolus Linnaeus and he is considered to be the Father of Taxonomy.

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BIOLOGY / CLASS-IX

Conventions and Rules (i) Scintific name of an organism consists of two words, generic and specific. (ii) Generic name (also called genus) is written first. It is like a noun. Its first letter is always capital. (iii) The specific name (also called Species) is written after the generic name. It begins with small letter. (iv) The names are either obtained from Latin language or are laitnised. (v) Scientific name is printed in italics. It is underlined in hand written form. Both generic and specific words are underline separately. Example Mangifera indica– Mango Incorrect Names : Mangifera Indica, mangifera Indica, mangifera indica

10. 11.

12.

Try yourself Scientific names are in which langugage (A) English (B) German (C) Latin (D) French According to rule of priority (A) Oldest name is valid (B) Latest name is valid (C) Both (A) and (B) (D) None of these In Trinomial nomenclature the sequence is genus species __________ (A) Kingdom (B) Class (C) Sub-species (D) None of these Advantages of Scientific Names (i) Universal : Scientific names are universal. They will be the same in all languages and countries. (ii) Unchangeable : The names are not liable to be changed with time. (iii) Distinct Name: Each organism has a single distinct and specific name. No two organisms have the same name. (iv) Relationships : The names indicate relationships of the organisms belonging to the same genus.

4.3

HIERACHY OF CLASSIFICATION A system of arranging taxonomic categories in a descending order on the basis of their relative dimensions is called hierarchy of categories. It was introduced by Linnaeus and is called Linnaean hierarchy. (i) Kingdom: It is the highest taxonomic category, e.g. Kingdom Monera, Kingdom Protista. (ii) Division / Phylum: Besides having all the characteristics of the kingdom, members of a division or phylum possess their own specific common characters called correlated characters, e.g., annelida, chordata, bryophyta. The term division is commonly used for plants and phylum for animals. (iii) Class: Its members have common characters of kingdom, division / phylum and also some specific correlated characters of their own, e.g. class monocotyledoneae, class mammalia.

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(iv) (v) (vi) (vii)

Order: All members of an order possess their own correlated characters. e.g., Primata, Carnivora. Family: It represents a grouping of some related genera. The category is subordinate to order, e.g. Poaceae, Canidae. Genus: It is a grouping of related species which is subordinate to the category of family e.g., Solanum, Panthera. Species: It is the lowest or the basic taxonomic category. Species is one or more potentially interbreedingnatural populationsofmorphologicallysimilarindividuals whichis geneticallydistinct and reproductivelyisolated from others e.g., Solanum tuberosum (Potato), Panthera leo (Lion). The hierachial classification of human is follows: Kingdom – Animalia Phylum – Chordata Class – Mammalia Order – Primata Family – Hominidae Genus – Homo Species – sapiens (Homo sapiens)

13. 14.

Try yourself Division is term used in classification of (A) Bacteria (B) Plant Scientific name is (A) Universal (B) Distinct

(C)Animals

(D)All of them

(C) Both (A) and (B) (D) None of these

Classification and Evolution: Classification is based on characteristics which occur in certain groups of organisms that make them different from other groups. These characters appeared during evolution. The idea that all present day forms have been developed due to accumlation of changes in body design is contained in the concept of evolution as proposed by Darwin (1859) in his book “Origin of Species”. Basis of Classification: Aristotle (384 – 322 BC, father of biology, father of zoology), Theophrastus (370 – 285 BC, father of botany) and Pliny the Elder (28 – 79 A.D.) used habitat and major habits of organisms in their classification. Aristotle classified animals on the basis of parts of the biosphere they live on /in – land, water and air. This brought butterflies, birds and bats in the same category. Classifications based on habitat and one or two morphological characters are called artificial systems of classification. They were used byall early taxonomists including Linnaeus (for classification of plants). The major drawback of all artificial systems of classification is that they do not reflect natural realtionships so that different types of organimsm get grouped together (e.g. birds , bats, insects) while related organismsm get separated (e.g., Bat , Whale and Rat).

CH-4: DIVERSITY IN LIVING WORLD

BIOLOGY / CLASS-IX

Natural Systems of Classification



They are those systems of classification which use a large number of characters to find out natural relationships based on their similarities and dissimilarities.



The system employs those characteristics which are relatively constant and related to their body design, form and function.



They are used in raising larger groups like kingdoms, divisions or phyla.



Then other characters are decided to raise subgroups. It is just like building a wall of stones.



This produces a hierachy of mutually related characteristics for classification. Some examples are follows: (i)

Complexity of Cell Structure: Cells are of two types, prokaryotic and eukaryotic. All organisms having prokaryotic cells are now placed in kingdom monera.

(ii)

Complexity of Body Structure: Organisms can be unicellular or multicelluar. All unicellular organisms with eukaryotic cell structure have been now placed in kingdom protista, e.g., Amoeba.

(iii)

Modes of Nutrition: Nutritionally, organisms are of two types, autotrophic and heterotrophic.

(iv)

Life Styles: They are of three types (i) Producers: They manufacture food through the process of photosynthesis. (ii) Consumers: Theyare animals and some other organisms which feed on other organisms for obtaining food. (iii) Decomposers: They are heterotropic organisms which feed on organic remains, e.g., fungi, many bacteria. Therefore, characteristics of body design used for classification of palnts would be quite different from characteristics of body design for raising subgroups of animlas.

Two Kingdom Classification Biologists, since the time of Aristotle have divided the living world into two kingdoms i.e., plantae and animalia. Linnaeus also divided the living organisms into two kingdoms in 1758. Kingdom Plantae :All the plants constitute kingdom plantae. The kingdom includes bacteria, lichens, fungi, algae, bryophytes, ferns, gymnosperms and angiosperms. KingdomAnimalia : All the animals constitute kingdom animalia. The kingdom animalia includes protozoans, sponges, Hydra, Jelly Fish, worms, insects, spiders, snail, octopus, star fish, fishes, frogs, salamanders, lizards, snakes, birds and mammals.

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Drawbacks in Two Kingdom Classification With the passage of time, it became clear that certain organisms did not strictly fit either under plant or animal kingdom. For example, (i) Euglena: It cannot be assigned with certainityto specific kingdom because it shares characteristics of both plants and animals. It possesses chlorophyll like plants but it lacks cell wall. It is autotrophic in light but in dark it becomes heterotrophic in its mode of nutrition like animals. (ii) Viruses : They belong to neither plant kingdom nor the animal kingdom because they share characteristics of both living and nonliving organisms.

15. 16.

4.4

Try yourself Unicellular eukaryotic organism is (A) Yeast (B)Amoeba Aristotle’s classification was (A) Natural (B)Artificial

(C)* Both

(D) None of these

(C) Scientific

(D) None of these

FIVE KINGDOM CLASSIFICATION Ernst Haeckel (1866, 1894) raised a third kingdom of protista to accommodate organisms that do not show differentiation of tissues. Copeland (1956) created the kingdom of monera for prokaryotic organisms. Whittaker (1969) classified organisms into five kingdoms – monera, protista, fungi, plantae and animalia. Carl Woese (1977, 1994) has divided the kingdom monera into archaebacteria (= archaea) and eubacteria (or bacteria). All other kingdoms are included in his superkingdom of eukarya.

CH-4: DIVERSITY IN LIVING WORLD

BIOLOGY / CLASS-IX

Monera It is a kingdom of prokaryotes. Monera is therefore, also called prokaryota. Characteristics: (i) Prokaryotic Nature (ii) Membrane Bound Cell Organelles are absent (iii) Unicelluar Nature: Monerans are basically unicellular. (iv) Flagella: Flagella, if present are single - stranded (v) Cell Wall : It is absent in some e.g. ( Mycoplasma) and present in others (e.g., bacteria, cyanobacteria). Basic structure of cell wall is made of murein or peptidoglycan (instead of cellulose). (vi) Nutrition: Both autotrophic and heterotrophic modes of nutrition. (vii) Nitrogen Metabolism:All nitrogen fixing organisms belong to monera (e.g., Rhizobium in root nodules oflegumes). Some monerans take part in ammonification, nitrificationand denitrification. Examples: Mycoplasma (produces diseases in humans, animals and plants), bacteria (e.g., Vibrio cholerae, Clostridium botulisum, Escherchia coli) and blue- green algae or cyanobacteria (e.g.,Anabaena, Nostoc.)

Do you Know: All nitrogen fixing organsims belong to kingdom Monera. For example, Rhizobium is found in the root nodules of legumes.

CH-4: DIVERSITY IN LIVING WORLD

BIOLOGY / CLASS-IX

Protista It is the kingdom of unicellular (and colonial) eukaryotes. Characteristics: (i) Organisation: Protists have simple unicellular and eukaryotic organisation. (ii) Locomotion: Locomotion is generally present. It occurs with the help of flagella (e.g., Euglena), cilia (e.g., Paramecium) and Pseudopodia(e.g., Amoeba). Flagella and cilia have 11-stranded sturcture. (iii) Cell Wall : Some protists are covered with cell wall (most photosynthetic protists) while others do not possess it (e.g., protozoan protists). (iv) Nutrition: It is diverse - photosynthetic (e.g., diatoms) holozoic (e.g.,Amoeba) and absorptive (e.g., Entamoeba). Photosynthetic nutrition occurs in protistan algae and Euglena like organisms. They are the major producers of aquatic systems. Holozoic nutrition is animal like nutrition where solid food particles are ingested. It is found in protozoan protists. In absorptive nutrition, liquefied digested food is absorbed. It occurs in parasites and saprophytes. Euglena and it relatives perform photosynthesis in light. In dark and in the presence of organic matter, they switch over to saprophytic nutrition. Such a dual nutrition is called mixotrophic nutrition. Such organisms are called plant-animals. (v) Sexual Reproduction: It is present but an embryo stage is absent. Examples: Dinoflagellates (e.g., Gonyaluax, Noctiluca), diatoms (e.g., Navicula), Euglena, Protozoans (e.g.,Amoeba, Paramecium).

Do you Know: Some of the protists are pathogenic. For example, Entamoeba histolytica, which cause dysentery and Plasmodium vivax that causes malaria.

CH-4: DIVERSITY IN LIVING WORLD

BIOLOGY / CLASS-IX

Fungi Fungi are achlorophyllous, heterotrophic spore producing, cell wall containing. Characteristics: (i)

Mycelium : The body of fungi is called mycleium. It is made of a number of fine threads called hyphae (singular hypha).

(ii)

Multicellular Nature: Fungi are basically multicellular. Yeast is an exception in being unicellular.

(iii)

Cell Wall: It contains a tough complex sugar called chitin or fungus cellulose.

(iv)

Nutrition: Fungi are heterotrophic with absorptive nutrition. Most of them are decomposers (hence kingdom of multicellular decomposers) or saprophytes which feed on organic remains by first secreating digestive enzymes and then absorbing the digested materials.Afew fungi are also parasitic.

(v)

Resverve Food: It is glycogen and oil.

(vi)

Sexual Reproduction: Fungi show progressive reduction in sexuality.An embryo stage is absent.

Examples:Yeast (Baker’sYeast, Brewer’sYeast),Agaricus (Mushroom), Penicillium (sourceof penicillin), Aspergillus, Rhizopus (Bread Mould).

Do you Know: Penicillium was the source of the first discovered antibiotic, penicillin. Yeasts (Saccharomyces) are widely used in baking bread and in wine making, etc.

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BIOLOGY / CLASS-IX

Lichens Theyare dual organisms which have been formed bypermanent symbiotic association between (i) an alga (generally a cyanobacterium or blue - green alga) and a fungus (generally and ascomycete). The alga manufactures food not onlyfor itself but also for the fungus. Fungus provides protection (ii) to alga, helps in fixation and absorption of water as well as minerals. Lichens can tolerate prolonged drought and drastic variations in temperature. (iii) They occur in hostile habitats like barren rocks, walls, tree trunks, icey regions where they can (iv) be seen as slow growing large coloured patches. Lichens are sensitive to air pollution. They are the source of dhoop and havan samagri, (v) some medicines (Usnea, Cladonia, Cetraria, Lobaria) and dyes (orcein, orchil, litums).

Plantae It is a kingdom of multicellular photosynthetic organisms having cellulose cell wall. Eichler (1883) divided the kingdom plantal into two subkingdoms, cryptogamae and phanerogamae. Subkingdom Cryptogamae: (Gk. cryptos – hidden, gamos – marriage). The reproductive organs are inconspicuous. Flowers and seeds are absent. The embryo, if present, is naked. Plants of subkingdom cryptogamae are also called lower plants, flowerless and seedless plants. There are three divisions in this subkingdom – thallophyta, bryophyta, pteridophyta. Subkingdom Phanaerogamae: (Gk. phaneros– visible, gamos – marriage). The plants of subkingdom phanaerogamae have well differentiated and evident reproductive organs like seeds. Therefore, they are also called Phanaerogamae has single division of spermatophyta.

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Differences Between Cryptogamae and Phanaerogamae:

17.

18. 19. 20.

Cryptogamae 1. It contains seedless plants.

Phanaerogamae 1. It contains seed producing plants.

2. It has both vascular and nonvascular plants.

2. It possesses only vascular plants.

3. Fertilization occurs in water only.

3. Water is not necessary for fertilization

Try yourself Mycoplasma are pleuromorphic because (A) They lack cell wall (B) They are prokaryotes (C) Both (A) and (B) (D) None of these Embryo of fungi is (A) Heart shape (B) Gobular (C) Both (A) and (B) (D)Absent in fungi Nitrogen fixing organisms belongs to (A) Monera (B) Protista (C) Plantae (D)All The pigment useful in Nitrogen fixation (A) Haemoglobin (B) Leghaemoglobin (C) Phycocyanin (D) Chloroplast Plant Classification Plant kingdom, as suggested by Eichler (1883) is subdivided into two subkingdoms : Cryptogamae and Phanerogamae. Subkingdom Cryptogamae (crypto-hidden, gamous-marriage). These plants do not bear external flowers or seeds and hence are considered to have hidden reproductive organs. Lower plants, flowerless or seedless plants. Plant Kingdom

Cryptogamae

Phanaerogamae

(Hidden marriage)

(Evident marriage)

Do not have differentiated plant body

Have differentianted plant body

Thallophyta Algae e.g., Spirogyra, Chlamydomonas

Without specialised vascular tissue Bryophyta e.g., Marchantia, Funaria

With vascular tissue Pteridophyta Do not produce seeds e.g., Dryopteris, Adiantum

Produce seeds Division spermatophyta

Angiosperms

Gymnosperms

(Seeds enclosed inside fruit

(bear naked seeds) e.g., Pinus, Cycas Dicots

(Seeds with two cotyledons) e.g.,Sunflower, Mango, Hibiscus

Monocots (Seeds with one cotyledon) e.g., Maize, Onion, Rice, Wheat

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21. 22. 23.

(A)

Try yourself Eichler’s classification was (A) Natural (B)Aritifical

(C) Both (A) and (B) (D) None of these

Gynosperm have (A) No seeds

(C) Covered seeds

(B) Naked seeds

In Lichen, the role of fungus is (A) Photosynthesis (C) Nitrogen fixation

(D) None of these

(B) Fixation of water and mineral (D) No role

Division Thallophyta (Thallus – undifferentiated ; Phyta – plant): (Gk. thallus – undifferentiated, phyta – plant) It is a division of plantae in which the plants do not have a well differentiated body design. Characteristics: (i) Simple body : The plant body is not differentiated into stem, root and leaves, but is in the form of an undivided thallus. (ii) VascularSystem: Thallophytahas a single subdivision of algae. In oldtwo-kingdom classification it also used to include bacteria and fungi.There is no vascular system. (i.e. no xylem and pholem) (iii) Reproductive Organs: The reproductive organs are single-celled and there is no embryo formation after fertilization. This division includes three distinct sub divisions : algae, fungi and lichens. (iv) The sex organs are unicellular and non jacketed. (v) Embryo Stage: Absent. Class – Algae They are thallophytes which are capable of manufacturing their own food through photosynthesis.Algae are mostly aquatic. Only a few occur in moist terrestrial habitats. Do you Know: Red and brown colours of red and brown algae, respectively are due to presence of large amount of accessory photosynthetic pigments in addition to chlorophyll. General Characters: (i) Plant body: Plant body is simple with little differentiation of body design. The common forms are thread-like (brached or unbranched) filament and parenchymatous thallus. (ii) Colouration: Algae are of three main groups–green, red and brown. Red and brown colours are due to the presence of large amounts of accessory photosynthetic pigments in addition to chlorophyll. (iii) Mucilage: The plant body is covered over by mucilage. (iv) Nutrition:Algae are autotrophs. (v) Cell Wall: The cell wall consists of cellulose. (vi) Reserve Food: The reserve food material is starch.

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Example: Ulothrix, Spirogyra (both unbranched filaments) ; Cladophora, Chara (branched filaments), Ulva (flat, parenchymatons thallus).

Class–Fungi (General Characters): (i) Cell Wall :The cell wall is made up of chitin (fungal cellulose). (ii) Reproduce: They reproduce by spores. (iii) The network of hyphae is known as mycelium. (iv) Nutrition:The fungi are heterotrophic because of their non-green nature. They obtain their food either from organic matter (saprophytic) or from other living organisms (parasitic). Bacteria are also included here. Difference between Algae and Fungi S. No. 1. 2. 3. 4.

Algae Algae are autotrophic Most of the algae are aquatic The cell wall is made of cellulose. Algae contains starch as a stored food material

Fungi Fungi are heterotrophic Most of the fungi are terrestrial The cell wall is made of chitin Fungi contains glycogen and oil as a stored food material

In Lichens the plant body is made up of two individuals, an alga and a fungus. Both get benefits by this symbiotic association.



Gametophyte : (Gk. gametos – spouse, phyton – plant). It is haploid (with one set of chromosomes) plant structure which produces gametes directly.



Sporophyte: (Gk. sporso – seed, phyton – plant). It is diploid (with two sets of chromosomes) plant structure which produces haploid spores through the process of meiosis. Sporophyte is formed from diploid zygote or fusion product of gametes.

CH-4: DIVERSITY IN LIVING WORLD

(B)

BIOLOGY / CLASS-IX

Embryophytas: Plants having an embryo stage in their life cycle– bryophytes, pteridophytes, seed plants. Division Bryophyta : (Gk. bryon – moss, phyton – plant) Bryophyta is a division of nonvascular plants having an embryo stage in their life cycle. General Characters: (i) Simple Land Plants: Bryophytes (plants of division bryophyta) are the simplest land plants. (ii) Amphibians: They are amphibians of plant kingdom. (iii) Absence of Vascular Tissue: Vascular system is absent. (iv) Rhizoids: Roots are absent. Plants are fixed by means of hair-like rhizoids. (v) Vegetative Structure: It may be thallus-like or differentiated into structures resembling stems and leaves. (vi) Gametophyte and Sporophyte: Plant body of bryophytes is gametophyte. Sporophyte lives as a parasite over it. (vii) Sex Orgns: Sex organs are multicellular and jacketed. Male sex organs are called antheridia while female sex organs are called archegonia. (viii) An embryo is formed upon fertilization. It includes liverworts, horn-worts and mosses. Tracheophyta: Plant group having vascular tissues – pteridophyta and spermatophyta. The sporophyte remains attached to the gametophyte and is dependent on it for nutrition. There is an alternation of sporophytic and gametophytic generations in their life cycle.

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(C)

Division Pteridophyta: (Gk. pteris – fern, phyton – plant) It is a division of seedless vascular plants which are commonly called vascular cryptogams. Pteridophyta represents the highest group of crytogamae. General Characters: (i) Plant body: They are the highest group of cryptogams in which the plant body is differentiated into leaf, stem and roots. (ii) Gametophyte : It is a small but independent stage in life cycle. (iii) Sex organs: They are multicellular and jacketed like those of bryophytes –male antheridia, female archegonia. (iv) External Water: Athin film of external water is required for swimming of male gametes upto archegonia. (v) Vascular Tissues: The vascular tissue (xylem and phloem) is present, therefore they are also known as vascular cryptogams. (vi) Seeds: They don’t produce seeds. (vii) Reproductive organs are multicellular. Fertilized egg develops into embryo ; for example, all types of ferns. Examples: Equisetum (Horsetail), Lycopodium (Club Moss), Marsilea (Water Fern), Dryopteris (Male Shield Fern),Adiantum (Walking Fern).

Different between Bryophyta and Pteridophyta Bryophyta 1. The plant body is not differentiated into true root, shoot and leaves.

Pteridophyta 1. The plant body is divided into true root, shoot and leaves.

2. The main plant body is gametophytic.

2. The main plant body is sporophytic.

3. Bryophytes are terrestrial nonvascular.

3. Pteridophytes are terrestrial vascular plants.

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Knowledge Enhancer: Pteridophytes are used for medicinal purposes and as soil-binders. They are also frequently grown as ornamentals. Evolutionarily, they are the first terrestrial plants to process vascular tissues - xylem and phloem. Interesting Fact: 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 veryinconspicuous, and theyare therefore called cryptogamae of those with hidden reproductive organs. Do you Know: The first three divisions of Plantae, namelyAlgae, Bryophyta and Pteridophyta are often collectively called non-flowering plants. They do not produce any flowers or seeds. (D)

Division Spermatophyta (Phanerogamae) (General Characters): The main plant bodyis sporophytic and is differentiated into true root, stem and leaves. The gametophytic phase is reduced and is completed within sporophyte. These are also called seed plants. Vascular system (xylem and phloem) is well developed. Sex organs are multicellular.An embryo develops from fertilized egg. (i) Pollination : Male gametophytes or pollen grains reach near the female sex organs through an external agencyof wind, water or animals. The process is called pollination. Fertilization occurs with the help of a pollen tube. An external water is not required. (ii) Seed: Reproductive process produces seeds. On germination each seed forms a new plant. Sub-Division – Gymnospermae : Subdivision Gymnospermae: (Gymnosperms, Gk. gymnos – naked, sperma – seed). Gymnospermae is the subdivision of seed plants in which the seeds are naked and the sporophylls are aggregated to form cones. On the basis of absence or presence of fruits, there are two sub-divisions : Gymnospermae and Angiospermae. General Characters: (i) Habit: Plants are evergreen, woody and perennial. They are trees and shrubs. (ii) Cones: Sporophylls are aggregated to form cones. There are separate male and female cones. (iii) Naked Seeds: The seeds are naked i.e., they are not enclosed by the fruit wall. (iv) Pollination: It is by wind. (v) Endosperm: Part of the haploid female gametophyte not used up in the formantion of embryo persists in the seed as food storage tissue called endosperm. (vi) VascularStrand: Xylem lackes vessels whilephloemis devoid of companioncells. Sieve elements are not organised into sieve tubes. They are called sieve cells.

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Examples: Cycas,Pinus (Pine), Cedrus (Deodar).

(b)

Sub-division Angiospermae : Angiospermae Gk. angio – cover, sperma – seed) Angiospermae is a subdivision of seed plants in which the seeds are produced inside fruits and the sporophylls are aggregated to form flowers. Members of angiospermae or angiosperms are also called flowering plants.

General Characters: (i) Habit: Plants are deciduous or evregreen, annual, biennial or perennial herbs, shrubs or trees. (ii) Fruit: The seeds are covered or enclosed by fruit wall. (iii) Flowers: Sporophylls are aggregated to form flowers. Flowers may be unisexual or bisexual. They possess sterile nonsporophylls on the outside. The reproductive organs are flowers. (iv) Pollination: It occurs by wind, water and animals. (v) Endosperm: It is a new food storing structure which is generallytriploid and is formed by fusion of three nuclei (triple fusion). (vi) Vascular Strand : Xylem contains vessels and phloem contains companion cells. (vii) Cotyledons: They are parts of the embryo called seed leaves because in certain cases they emerge and become green to function as leaves. In angiosperms, a seed may have two or one cotyledon. On the basis of cotyledon number, angiosperms have been divided into two classes, dicotyledoneae and monocotyledoneae.

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(a)

Class Dicotyledoneae: It is a class of angiosperms in which seeds possess two cotyledons. The plants of this class are commonly called dicots or dicotyledonous plants. Some other characters are reticulate venation, tap root system, pentamerous or tetramerous flowers, occurrence of secondarygrowth in perennial plants and concentric arrangement of tissues in the stem. Common examples are Mustard, Pea, Green Gram, Mango, Rose, Ipomea.

(b)

Class Monocotyledoneae: The members of class monocotyledoneae of angiosperms are characterised by the occurrence of a single cotyledon in their seeds.They are commonly called monocots or monocotyledonous plants. Other characters of monocots are parallel ventaion, fibrous root system, trimerous flowers, absence of secondary growth and occurrence of uniform ground tissues in the stem instead of concentric arrangement of tissues. Common examples are Lily, Coconut, Wheat, Maize, Grass, Bamboo.

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CH-4: DIVERSITY IN LIVING WORLD

Difference between Dicotyledoneae and Monocotyledoneae Dicotyledoneae 1. In the seeds, the embryo bears two cotyledon. 2. The leaves show reticulate venation. 3. The plants have tap root system. 4. Secondary growth occurs. 5. Flowers are pentamerous (have five of each floral part) or tetramerous.

Monocotyledoneae 1. In the seeds, the embryo bears one cotyledons. 2. The leaves show parallel venation. 3. The plants have adventitious root system. 4. Secondary growth does not occur. 5. Flowers are trimerous (have three of each floral part).

Differences between Gymnosperms and Angiosperms Gymnosperms 1. The seeds are naked. 2. Xylem lacks vessels and phloem lacks companion cells. 3. The ovules are not located in the ovary. 4. The microspores and megaspores are produced by male and female cones.

Angiosperms 1. The seeds are enclosed by fruit wall. 2. Xylem contains vessels and phloem also contains companion cells. 3. The ovules are enclosed in the ovary. 4. The microspores are produced in anthers while the megaspores are produced in ovules of the ovary in flowers.

Note:



Herbs have soft, flexible and usually green stem.



Shrubs have medium height (1 – 4 m), woody stem, bushy in appearance.



Trees have a thick woody stem which may or may not be branched.



Flower is basicallya shoot which has been modified in angiosperms for carrying out the process of sexual reproduction. Flower bears sepals, petals, stamens and carpels. Sepals are green ; petals are brightly coloured ; anther develops pollen grain ; carpels have ovary.



When one male gamete (n) fuses with the egg cell (n) to form zygote (2n) and other male gamete fuses with the secondary polar nucleus (2n) (Two primary polar nuclei fuse to form secondary polar nucleus) to form endosperm mother cell (3n). This process is known as double fertillization. It is observed in angiosperms and it is absent in gymnosperms.



Endosperms mother cell divides to form endosperm. It is triploid in angiosperms and provide nutrition to developing embryo.

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24. 25. 26. 27. 28.

29. 30.

31. 32. 33. 34.

Try yourself Vascular system ofAlgae comprise of (A) Xylem (B) Phloem

(C) Both

(D)Absent inAlgae

Amphibia of plant kingdom is (A)Algae (B) Fungi

(C) Bryophyta

(D) Pteridophyta

Sex organs in fungi (A)Absent

(C) Multicellular

(D) None of these

Parasexual hybridization occurs in (A) Human (B)Algae

(C) Fungi

(D) Plants

Diploids have (A) No chromosome (C) Two set of chromosome

(B) One set of chromosome (D) None of these

Cross pollination occurs with help of (A) Wind (B) Water

(C)Animal

Double fertilization in Gymnosperm includes (A) Fusion of eggs (C) Both

(B) Fusion of polar nuclie (D)Absent in Gymnosperm

(B) Unicellular

(D)All

Secondary growth occurs in (A) Dicotyledoneae (B) Monocotyledeneae (C) Both

(D) None of these

Parallal venation is found in (A) Monocots (B) Dicots

(C) Both

(D) None of these

Flower bears (A) Stamen

(B) Carpel

(C) Petal

(D)All

Vascular system consists of (A) Xylem (B) Phloem

(C) Both

(D) None

Animal Classifications Animals are devided into several phyla mainlyon the basis of their cell organisation, symmetry, presence or absence of notochord and bodycavity. In the two kingdom system animals are arranged progressively from simple single-celled protozoans to highlycomplex animals. Charcteristics of Animalia: (i) Cellular Nature: Members of kingdom animalia are wall - less eukaryotic and multicellular. (ii) Nutrition : It is holozoic or ingestive.An internal alimentary canal is present for intercellular digestion and absorption of food in most animals. Digestion intracellular in primitive animals. The undigested matter is thrown out.

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(iii)

Growth : It is limited and stops after reaching maturity.

(iv)

Definite Shape, Size and Symmetry : Animals generaly possess a definite shape, size and symmetry. Exceptions occur in some lower forms.

(v)

Locomotion : Most animals are mobile. Mobility is required for obtaining food and other necessities. Sponges and corals are however, sedentary.

(vi)

Muscular and Nervous System : Movements occur in animals with the help of muscular system. Information is conveyed to different parts of the body by nervous system which also provides stimulus to muscles for contraction.

(vii)

Organisation : It is cellular, tissue, organ and organ system level.

Important Terms: Organisation: It is a structural differentiation of animal body (i)

Cellular Organisation : Tissues do not differentiate. Different types of cells may occur, e.g., proifera (sponges).

(ii)

Tissue Level Organisation : Multicellular body has cells organised into tissues but organs are absent, e.g., coelenterata.

(iii)

Organs Level Organisation : Cells are organised into tissue and organs but organ systems are absent, e.g., platyhelminthes.

(iv)

Organ System Level Organisation : Cells are organised into tissues, tissues into organs and organs into organ systems e.g., nematoda and higher animals.

Body Symmetry: It is similarity in arrangement of parts.Absence of any repetition or similarityis called asymmetery. Symmetry is of two types, radial and bilateral. (i)

Radial Symmetry : The body is cylindrical or discoid where similar parts occur all around the central axis.Any vertical plane passing through the central axis will divide the body into two equal halves, e.g., many sponges, coelenterates and echinodermates. Head is generally absent.

(ii)

Bilateral Symmetry : The body has a head. Organs and limbs are paired. They are arranged laterally. Body is divisible into two equal halves byonly one plane (mid-sagittal plane). Bilateral symmetry is found in platyhelminthes, nematoda, annelida, mollusca, arthropoda and chordata.

Cephalization: It is development of head in the anterior part of the animal body. Germ or Germinal Layers : They are the primarylayers that differentiate in the embryo.All tissues and organs of the animal body develop from them. Germinal layers can be two or three in number. On this basis, the animals are of two types, diploblastic and triploblastic. (i)

DiploblasticAnimals :Animals have two germinal layers, outer ectoderm and inner endoderm. Mesoderm is absent, e.g., porifera, coelenterata.

(ii)

Triploblastic : Animals have three germinal layers - outer ectoderm, middle mesoderm and inner endoderm, e.g. platyhelminthes of chordata.

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Coelom (Body Cavity): It is mesoderm lined fluid filled space that occurs between alimentary canal and body wall which provides shock proof environment to various body organs. Depending upon the absence, presence and nature of coelom, animals are of three types – acoelomate, pseudocoelomate and eucoelomates. (i) Acoelomate : Coelom is absent e.g., porifera, coelenterata, platyhelminthes. In platyhelminthes a mesoderm is present but it does not form a cavity. (ii) Pseudocoelomate : Acavity called pseudocoelom is present which is not lined by mesoderm. It is generally endodermal in origin. Mesoderm occurs but forms small seperate pouches, e.g., nematoda.

35.

36.

37.

38.

Try yourself Most primitive organisms are included (A)Annelida (B) Porifera

(C) Mollusca

(D) Protozoa

The structure absent from animal cell (A) Cell wall (B) Nucleus

(C) Mitochondria

(D)All

Body symmetryin Echinodermata is (A) Radial (B) Bilateral

(C)Asymmetric

(D)All

Nematoda is (A) Coelomic

(C)Acoelomic

(D) None

(B) Pseudocoelomic

The outline classification of animal kingdom is given below: (A)

Phylum Protozoa (early animals) (i)

Single-celled (unicellular), mostly aquatic (fresh and marine water), free-living or parasitic organisms.

(ii)

Locomotion is by finger-like pseudopodia (pseudo-false, podia-feet), flagella or cilia.

(iii)

Nutrition is mostly heterotrophic.

(iv)

Reproduction is through binary or multiple fission and conjugation. For examples, Amoeba, Euglena, Paramecium and Plasmodium.

(v)

Saprophytic nutrition means it can absorb organic substances from the environment (feed on decaying matter).

(vi)

Myxotrophic nutrition – organisms which are autotrophic as well as saprophytic. Example, Euglena.

Examples: Paramoecium (commonly known as slipper animalcule, it is binucleated, has cilia for locomotion); Trypanosoma (with flagella, is parasite of man, causes a disease African sleeping sickness). Plasmodium causes Malaria. Campus : 2–K–17, Vigyan Nagar, Kota–5 (Raj.) | Contact : 0744–2423245, +91–8003038222 A Pre-Foundation Program

E-mail : [email protected] | www.bansal.ac.in

PAGE# 26

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(B)

Phylum Porifera includes sponges. (i) Habitat : They are mostly marine but a few live in fresh water.e.g. Spongilla (ii) They are multicellular animals with a cavity called spongocoel. They attach themselves to objects in the adult stage and thus become stationary (sessile). (iii) Sponges may be vase-like, rounded, sac-like or branched. (iv) Organisation : The body possesses many cells, but these are not organised into tissues. They have porous body with innumerable pores called ostia (work as mouth) and a single exhalent pore called osculum (works as anus). (v) The canal system consists of pores, canals and chambers through which water circulates with the help of flagellate choanocytes (flagellate collar shaped cells). Water brings food and oxygen. (vi) Skeleton is made up of calcareous or siliceous spicules or spongin fibres of either calcium carbonate or silica or spongin fibres (made up of protein). These spicules form endoskeleton. (vii) Reproduction is both asexual by budding and gemules and sexual through fertilization. (viii) Digeston is intracellular (digestion take place within the cell). (ix) Respiration and excretion take place by diffusion through the general surface of the body. Examples: Leucosolenia (simplest sponge), Scypha or Sycon, ‘Euplectella (Venus Flower Basket), Euspongia (bath sponge), Spongilla (fresh water sponge).

(C)

Phylum Coelenterata (koilos = hollow ; enteron = intestine) Phylum Cnidaria (Coelenterata) includes Hydra, jelly fish, Sea anemone and corals. (i) Habitat: It includes aquatic (both fresh water and marine), solitary or colonial forms. (ii) Show radial symmetry their body can be divided into two halves by any plane passing through the centre. (iii) Coelenterata are unique in having slender, finger like projections called tentacles. Tentacles are collered with stinging cells or cnidoblasts or nematoblasts. (iv) A cavity in the centre of the body called gastrovascular cavity or coelenteron is present. (v) Reproduction is usually asexual (budding) in polyp form and sexual in medusa form. (vi) When digestion of food takes place within the cell then it is known as intracellular digestion whereas when digestion takes place outside or in between two cells it is known as intercellular digestion. (vii) Respiration and excretion takes place through general body surface. (viii) Primitive type of nervous system present but brain is totally absent. (ix) Many forms possess a hard exoskeleton of lime to form corals. (x) Neurons or nerve cells develop first in this phylum. Examples : Hydra, Obelia, Aurelia, Metridium. Examples:(Soeitary life) Hydra, Physalia (Portugese man - of - war),Aurelia (Jelly fish), Metridium (sea - anemone).

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Differences between Porifera and Coelenterata Poriferans 1. They possess cellular level organisation. 2. The body has several pores, ostia and oscula. 3. Digestion is intracellular. 4. Muscle and nerve cells are absent. 5. Appendages are absent. 6. Special cells are choanocytes or collar cells.

Coelenterates 1. Coelenterates have tissue level organisation. 2. The body has usually a single opening. 3. Digestion is both intracellular and intercellular. 4. They appear for the first time in coelenterates. 5. Appendages occur in the form of tentacles. 6. Special cells are cnidoblasts.

(D)

Phylum Platyhelminthes (flatworms) includes tapeworms, flatworms and flukes. (i) They are metazoa with organ level of organsiation. They are free living or parasite. (ii) They possess bilateral symmetry (Animals can be divided into two halves by just one plane). Body cavity (coelom) is totally absent means they are acoelomate. (iii) Excertion takes place through flame cells. (iv) Nervous system is well developed. Primitive brain is also formed. (v) They are mostly parasitic, some are free living (e.g., Planaria). (vi) Most of them are hermaphorite (organism contains both male and female sex organs). (vii) Their body is dorsoventrally flat and leaf-like or ribbon-like (platy-flat). (viii) They are the first triploblastic animals which means their tissues differentiate from three embryonic germ layers, but without a body cavity or coelom. (ix) Life history includes variety of larvae. (x) In Taenia digestive system is totally absent, so, absorb food from body surface. Examples: Physalia (Portugese man – of – war), Aurelia (Jelly fish), Metridium (sea – anemone). Dugesia (commonlyknown as planaria, it is free living), Schistosoma (blood fluke), Fasciola (commonly known as liver fluke), Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm). Parasites which complete their life cycle on one host are known as monogenetic parasites whereas, those parasites which complete their life cycle on two hosts are known as digenetic parasites. Fasciola and Taenia solium are digenetic parasites. Hooks and suckers are organs of attachment in parasitic forms.

(E)

Phylum Aschelminthes / Nemathelminthes/ Nematode – The Round worms.(Nema– thread, Helminth – worm) (i) They are parasitic or free-living. (ii) Body size varies from microscopic to several centimeters in length. (iii) They are triploblastic, unsegmented and of bilateral symmetry. (iv) They are metazoa which are triploblastic and have a primitive organ -system level of organisation where organs are not well defined (hence tissue level of organisation) although a false cavity or pseudocoelom is present. (v) Digestive system has both mouth and anus. Respiratory system and circulatory systems are lacking.

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(vi) (vii) (viii) (ix)

Alimentarycanal is complete. Sexes are seperate (unisexual) and females produce large number of eggs. MaleAscaris is smaller than femaleAscaris. The posterior end of male Ascaris is curved whereas the posterior end of female Ascaris is straight. (x) The Pineal setae (project out through cloacal aperture and help in reproduction) are present in maleAscaris but absent in femaleAscaris. (xi) Filarial worm is transmitted by female Culex mosquito. (xii) Cloaca is a common aperture through which undigested waste, excretory waste and gametes are passed. Examples: Ascaris (round worm), Ancylostoma (hook worm), Wuchereria (Filarial worm cause elephantiasis), Enterobius (Pin worm). (F)

PhylumAnnelida – the segmented animals. (Annulus = ring ; lidos = form) The phylum consists of triploblastic bilaterlally symmetrical animals having organ system level of organisation (i) They occur in moist soil, fresh water and sea. (ii) They are elongated, with segmented body and bilateral symmetry. (iii) First animals with true body cavity (coelom). (iv) Metameric segmentation is a type of segmentation where external divisions correspond to inernal divisions. Each segment is known as metamere. (v) Chitinous setae are locomotory structures in all annelids except leech. Nereis also has parapodia for locomoton. (vi) Blood in annelids is red due to the presence of haemoglobin. It is dissolved in plasma. RBC are absent. (vii) Digestive system is well developed. Respiration by gills or skin. Circulatory system is closed (blood flows in well formed blood vessels). (viii) Excretory system consists of excretory units called nephridia. (ix) Sexes may be seperate (unisexual) or united (hermaphrodite). (x) Reproduction is by sexual means. Example: Nereis (sand worm) Aphrodite (sea mouse), Pheretima (earthworm), Hirudinaria (cattle leech) Leech-an ectoparasite which suckes blood from the host.

(G)

Phylum Arthropoda (Arthro = Jointed ; Poda = Legs) It is phylum of triploblastic bilaterally symmetrical segmented animals having jointed legs, jointed appendages, a chitinous exoskeleton and blood filled body cavity called haemocoel. (i) Animals with jointed feet is largest phylum, which includes prawns, shrimps, insects, spiders and scorpions. (ii) They are found everywhere, on land, in soil, in fresh and marine water and as parasitic on other animals and plants.

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(iii) (iv)

The phylum arthropoda includes the largest number of animals about 1 lakh. The body is segmented and the segments are grouped into two regions – cephalothorax (head and thorax together) and abdomen, or three regions – head, thorax and adbomen. (v) Anterior part of body forms a distinct head, bearing sense organs and brain. (vi) Exoskeleton is chitinous (made of a hard substance called chitin) and jointed. (vii) Body cavity is reduced and filled with blood (called haemocoel). (viii) Exoskeleton of arthropods is light – weight,tough andcomposed ofstructural polysaccharide chitin. (ix) Circulatory system is said to be open when, blood is present in the open spaces known as lacuna or sinuses. Example : – Arthropoda and mollusca. When blood circulates inside the blood vessels without ever coming in direct contact with the body cells then it is known as closed system. Example – chordates and annelids (except leech). (x) Respiration is by gills, trachea, booklung, etc. Sexes are separate. (xi) Excretion takes place by malpighian tubicles (insects) and green glands (crab and prawn). (xii) In many arthropods, compound eyes are present, in which mosaic vision is developed. (xiii) Sexes are separate. The development of the animal may involve metamor-phosis. Example: Palamonaeous (Scorpion), Palaemon (prawn), Musca (housefly), Cancer (crab), Scolopendra (Centipede), Julus (Milipede), Aranaea (Spider), Anopheles, (Silver fish), Periplaneta (Cockroach), Termite, Apis (honey bee), Ant. Differences between Annelids and Arthropoda

Annelids 1. Appendages are unjointed. 2. Blood flows inside blood vessels (closed circulatory system). 3. True coelom is well developed. 4. A chitinous exoskeleton is absent. 5. Excertory organs are nephridia.

Arthropods 1. Appendages are jointed. 2. Blood flows through large sinuses or spaces (open circulatory system). 3. True coelom is small. Instead, blood filled body cavity called haemocoel is present. 4. A chitinous exoskeleton is present. 5. Excretory organs are green glands and tubules. 6. Sensory system is well developed.

6. Sensory system is less developed.

Largest class of phylumArthopoda is insect.

39.

40. 41.

Try yourself Paramecium has (A) No nucleus (C) Two nucleus

(B) Single nucleus (D) More than two nucleus

Larvae of sponge is (A) No larva present

(B) Motile

(C) Sessile

(D)Attached to surface

Jellyfish is (A) Fish

(B) Arthopoda

(C) Mollusca

(D) None

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CH-4: DIVERSITY IN LIVING WORLD

42.

43.

44.

45.

Cephalization first occurs in (A)Annelida (B) Flatworm

(C) Roundworm

Round worm circularatory system is (A) Open (C) May be open or close

(B) Close (D)Absent

(D) Mammals

Excretory organ of flatworms:(A) Kidney (B) MalphigianAubule (C) Flame cell

(D) Body surface

Arthopoda are most successful animals because of (A) Coelome (B) Brain (C) Joint appendage

(D) Chitinaceous exoskelton

(H)

Phylum Mollusca– The soft bodied animals :It is phylum of triploblastic soft bodied but shelled animals with reduced coelom, open circulatory system, little segmentation where the body is differentiated into head, foot and visceral mass covered by a special fold called mantle. General Characters: (i) Mollusca is the second largest phylum. (ii) Soft–bodied animals with a protective shell. (iii) Body cavity is filled with blood. Circulatory system is open. (iv) Muscular foot is present for locomotion. (v) Body is divided into three regions : (head, dorsal visceral mass and ventral foot). (vi) Outer surface is covered by a hard calcareous shell. (vii) Respiration is by gills called ctenidia. (viii) The sexes are usually separate. (ix) Radula – sensory organ. (x) They are: usually bilaterally symmetrical and body cavity is filled with blood (haemocoel). Circulatory system is open. Body is unsegmented. Example: Pila (apple snail), Unio (fresh water mussel), oyster, Sepia (cuttle fish), Loligo (squid) and Octopus, Chiton (Coat of mail shell).

(I)

Phylum Echinodermata – the spiny skinned animals (Echinos = Epines ; Derma = Skin / covering). General Characters: (i) All echinoderms are found in marine water.They are pelagic (free swimming in open water), benthonic (bottom dwellers), while a few are sessile (attached to the substratum). (ii) Tube feet helps in locomotion. (iii) They are marine, gregarious (live in groups) and free-living animals. (iv) Shape may be star-like, spherical or elongate. (v) Body surface is covered all over by calcareous spines.

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(vi) (vii) (viii)

Their symmetry is radial in adults but bilateral in larvae. These are unsegmented. Body cavity is modified into a water-vascular system with tube like outward extension for locomotion, called tube feet. WVS – aids in respiration and locomotion. (ix) Sexes are separate: But no sexual dimorphism. They have extensive power of regeneration. Examples:Asterias (star fish), Echinus (sea urchin), Holothuria (sea cucumber),Antedon (feather star).

(J)

Phylum Hemichordata (Hemi = half + chordata = notochord). Phylum Hemichordata includes worm -like, unsegmented animals which are exclusivelymarine. These possess a combination of invertebrate and chordate characters. They are connecting link between nonchordates and chordates. (i) Body is divided into proboscis, collar and trunk. (ii) Symmetry is bilateral. (iii) Respiration is through gill slits. (iv) Sexes are mostly separate. Example: Balanoglossus (tongue worm).

(K)

Phylum Chordata : The Phylum Chordata is the most advance group of animals. The main distinctive characters of this group are the presence of (a) Notochord (b) Dorsal, tubular, hollow nerve cord (c) Presence of pharyngeal gill slits (d) Post anal tail. (i) It is a long rod-like structure that develops between dorsal nervous system and gut. In higher chordates, notochord is transformed into cranium and vertebral column. (ii) Dorsal Hollow Nerve Cord : It occurs above the notochord. In higher chordates it gets transformed into brain and spinal cord. (iii) Pharyngeal Gill Slits : (Gill Pouches) : They are paired respiratory structures which remain functional throughout life in fishes and some amphibians. In others they occur only in embryo. (iv) Post-anal Tail : It occur in most chordates for balancing, protection of genital and anal regions. Other Characteristics : Chordates have bilateral symmetry, organ system level organisation triploblastic development, enterocoelom, prounced cephalization system, closed circulatory system, well developed excretory system based on kidneys and an integumentary system (single layered in protochordates and multilayered in vertebrates). Chordates are divided into three subphyla : Urochordata, Cephalochordata and Vertebrata. The first two subphyla together are also known as lower chordates or protochordates. (i) Subphylum Urochordata (Uros = tail + chordata = notochord) Exclusivelymarineanimals : • Body is unsegemented and usually adults lack tail. • Body is covered by a tunic. Notochord occurs in tail in larval forms only. • Hollow nerve cord is also there in larva only. • Pharynx has several gill slits. Examples : Herdmania, Doliolum, Pyrosoma.

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BIOLOGY / CLASS-IX

(ii) •

Subphylum Cephalochordata (Cephalos = head + chordata = notochord). Their notochord extends upto anterior end of the body and persists throughout life. Example:Amphioxus. • It includes tiny fish-like chordates without a head. • It possesses all the characters of chordates, i.e. a notochord extending to entire length, a nerve cord (without a distinct brain), numerous gill slits and a post anal tail. Example : Branchiostoma (Amphioxus). (iii) Subphylum Vertebrata (Craniata) • Head is well differentiated. • Nervous system and endoskeleton highly developed. • Notochord is replaced by vertebral column (back bone) in the adult forms (Notochord is present in the embryonic stage). There are two pairs of appendages. Class: Cyclostomata. • It includes lamprey and hag fish. • These are most primitive vertebrates. • They are without jaws. • The mouth does not possess jaws hence namedAgnatha. Unpaired fins are present. • Mouth is suctorial as they are ectoparasites and use mouth to stick to back of other fish. • Notochord present in the form of cylindrical rod. • Respiration is bygills contained in pouches. • Heartistwochambered.Gonadissingleandfertilizationexternal.Example:Petromyzon,(Lamprey). Differences between Nonchordates and Chordates Nonchordates 1. Notochord is absent. 2. Central nervous system is solid and ventral. 3. Heart, if present, in dorsal. 4. Vascular system may be open or closed. 5. Haemoglobin, if present, is dissolved in plasma. 6. Pharyngeal gill slits are absent. 7. The anus is posterior, so no post-anal tail.

Chordates 1. Notochord is present at some stage of development 2. It is hollow and dorsal. 3. Heart is ventral. 4. Vascular system is closed. 5. Haemoglobin is present in red blood corpuscles. 6. Pharyngeal gill slits are present. 7. A post-anal tail is present.

Superclass Pisces General Characters: (i) Stream lined body covered with scales. (ii) Lateral line sense organs pesent. (iii) Cold–blooded vertebrates with true jaws. Note : • Animals, in which the body temperature varies according to surrounding environment are called cold blooded or poikilothermal animals. Example – Invertebrates, Pisces,Amphibia and Reptilia. • Animals, in which the body temperature remains constant and does not change with the change of environmental temperature are called warm blooded or homoiothermal animals. Example: Birds and Mammals.

CH-4: DIVERSITY IN LIVING WORLD

BIOLOGY / CLASS-IX

Class: Chondrichthyes (cartilaginous fishes) • It includes sharks, rays and skates. • They are mostly marine, and generally large in size (upto 10-20 meters long). • Skin is covered with placoid scales. • Skeleton is completely cartilaginous. • Respiration is through gills. • Air bladder is absent. Example : – Torpedo (electric ray), Scoliodon (dog fish), Trygon (sting ray). Class: Osteichthyes (bony fishes) • Bony fishes are found in fresh water as well as in sea water. • Fishes with endoskeleton consisting of bone. • Air bladder is present, it helps in maintaining buoyancy. Example: Labeo rohita (Rohu), Catla catla (Katla), Gambusia (mosquito fish), Exocoetus (flying fish), Hippocampus (sea horse), Anabas (Climbing perch), Protopterus (lung fish). Note: • Gambusia eats on the larvae of mosquito. It is used to control mosquitoes. • Bony fishes are the most successful of the vertebrates, accounting for more than half of all living vertebrate species. • In Hippocampus, male bears a brood pouch in which the female lays eggs. • Flying fish does not fly but glide. Class: Amphibia (Amphi = two or both ; bios = life) • They live in fresh water and moist places. • Body varies in form and is without scales. • There are mostlytwo pairs of pentadactyl (five digits) limbs, which maybe absent in some cases. • Respiration is by gills, lungs or skin. • Skin is smooth and without scales. • Heart is three chambered. • External ear absent (but ear drum presnt). Example: Salamandra (salamander), Rana (frog), Bufo (toad), Hyla (tree frog), Necturus (mud puppy). Note: • Most of the amphibians undergo hibernation (winter sleep) and aestivation (summer sleep) to overcome the unfavourable condition. • Limbless amphibian – lchthyophis. • Tadpole is the larva of frog. • Frog is active in day whereas toad is active at night. • Skin of frog is moist and smooth whereas skin of toad is dry and rough. • Frog has webbed feet whereas in toads it is absent.

CH-4: DIVERSITY IN LIVING WORLD

BIOLOGY / CLASS-IX

Class: Reptilia. The creeping vertebrates. (Reptare – to creep). • They are mostly terrestrial and live in warmer regions. • Body varies in form and is covered by scales. • Respiration is by lungs only. • Reptilia is the first class of terrestrial animals. • Skin in dry, rough and without glands. • Theybear twopairs of pentadactyl (five digit) limbs, whichare absent in snakes and some lizards. • Heart is generally 3-chambered. Note : • Reptiles are successful on land because of – (a) Internal fertilization (b) Shell around egg (c) Dry, scaly skin (d)Amnion(embryonicmembrane) encloses the embryoand provides it witha wateryenvironment during development. So, embryo does not need water for development. • Chameleon has the ability to change the colour of its body according to the surrounding. • Limbless reptile – Snake. • Wall lizard can break of its tail to escape from the enemycalled autotomy. It can move on ceiling and smooth surfaces due to vacuum pads on its toes. • Poisonous snakes are – Cobra, Krait, Viper, Sea snake. • Non – poisonous snake Python : Class: Aves. The birds (Aves = Bird) • Fore limbs are modified into wings. • Body is covered with feathers. • Skeleton is light. • Mouth is surrounded by a beak modified for different purposes. • Respiration is by lungs only. • First group of flying animals, having exoskeleton of feathers. • warm blooded animals. • Forelimbs are modified into wings while hindlimbs have four clawed digits. • Pneumatic bones • Teeth are absent. • Four chambered heart Example: Struthio (Ostrich – largest flightless bird), Pavo (Peacock – National bird of India), Columba (Pigeon), Passer (Sparow), Budo (Owl) etc. Note : • The largest bird is ostrich. • Sun birds are the smallest among Indian birds. • Dove is the emblem of the sign of peace. • The humming bird is the only bird which can fly backward as well as forward. • Ornithology – study of birds. • Salim Ali was a famous Ornithologist. He was known as “Bird man of India”. • Owl can rotate its head through an angle of 270° (because eyes are fixed in eye socket). • Emu, Ostrich, Kiwi, Penguins are some flightless birds.

BIOLOGY / CLASS-IX

CH-4: DIVERSITY IN LIVING WORLD

Class: Mammalia (Mamma = Breast) They are primarily terrestrial and occupying all sorts of habitats. • Body is of varied shape, covered with hairs. • They have two pairs of pentadactyl limbs modified for various purposes. • Respiration is by lung only. • Heart is 4–chambered. Example: Macropus (Kangaroo), Rattus (rat), Canis (dog), Felis (cat), Panthera (lion, tiger, leopard) Homo sapiens (man), Platypus, Balaenoptera (whale), Elephas (elephant), Macaca (rhesus monkey), Pan (chimpanzee). Note : • Oviparious – Egg laying animals. Example from mammals – Platypus, Echidna • Females having marsupium or brood pouch for rearing the young ones – Example from mammals – Kangaroo. • When embryos are retained in the womb and the adult female gives birth to young ones – Viviparous. Example – Cattles, human being. • Largest animal – Blue whale • Largest ape – Gorilla. • Most intelligent ape – Chimpanzee. • Tiger – National animal of India.

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Try yourself Largest class of animals is (A) Insecta (B) Nematoda Millipede have (A) No legs

(C) Both

(B) 10–30 pairs of legs (C) 70–100 pairs

(D) None

(D) 1000 pairs

Locomotion in Mollusca is by (A) Flagella (B) Pseudo podia

(C) Muscular foot

(D)All of these

Fresh water Echinodermata is (A) Star fish (B) Sea Urchin

(C) Feather star

(D) None

Chordata have (A) Notochord (C) Postanal tail

(B) Dorsal, hollow nerve cord (D)All of the above

Temperature of fish body is (A) 37°C (C) 28°C

(B) 40°C (D) Varies according to environment

Egg layingmammal is (A) Platypus

(C) Kangaroo

(B) Blue whale

(D) None