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3_Diversity of Life – class 9

Classification of Organisms

  • Out of 1.7 million organisms 1.2 million are animal (insects 0.75 million) and 0.5 million are plants. About 15,000 new organisms are added to the list every year. They live in diverse habitats (aquatic and terrestrial) from the mountain peaks to ocean depths. 40% of organisms live in 8% tropical rain forest. If the total organisms evolved only 1% is living, rest are all extinct. For proper study of diversity the organisms are arranged in orderly manner in small and large groups on the basis of their features. This is called biological classification.
  • Taxonomy (de Candole, 1813) is the science of identification, nomenclature and classification of organisms.
  • Systematics (term by Linnaeus) is the “science of diversity” including phylogenetic interrelationship of organisms. Both taxonomy and systematics are complementary discipline, hence often used interchangeably.
  • Classification, in biology, identification, naming, and grouping of organisms into a formal system based on similarities such as internal and external anatomy, physiological functions, genetic makeup, or evolutionary history.
  • Classification determines methods for organizing the diversity of life on earth. It is a dynamic process that reflects the very nature of organisms, which are subject to modification and change over many, many generations in the process of evolution.

Classification Methods

  • Scientists classify organisms using a series of hierarchical categories called taxa (taxon, singular). This hierarchical system moves upward from a base containing a large number of organisms with very specific characteristics. This base taxon is part of a larger taxon, which in turn becomes part of an even larger taxon. Each successive taxon is distinguished by a broader set of characteristics.
  • The base level in the taxonomic hierarchy is the species. Broadly speaking, a species is a group of closely related organisms that are able to interbreed and produce fertile offspring. On the next tier of the hierarchy, similar species are grouped into a broader taxon called a genus (genera, plural). The remaining tiers within the hierarchy are formed by grouping genera into families, then families into orders, and orders into classes.

History of Classification Systems

  • Aristotle divided animals into those with blood and those without blood, a classification that roughly corresponds to the division between vertebrates and invertebrates used in contemporary classification schemes.
  • Aristotle wrote extensively on both plants and animals, but his writings on plants were lost. Theophrastus subdivided plants, based on shape, into such broad categories as trees, shrubs, and herbs.
  • In the mid-1700s, Swedish naturalist Carolus Linnaeus developed formal rules that provided consistency for a two-name system in common use called the binomial system of nomenclature. In this system, similar organisms are grouped into a genus, and each organism is given a two-word Latin name. The first word is the genus name, and the second word is usually an adjective describing the organism, its geographic location, or the person who discovered it. Using this system, the domestic dog is Canis familiaris. Canis is the genus name for the group of animals that includes dogs, wolves, coyotes, and jackals. The word familiaris acts as a descriptor to further differentiate the domestic dog from its wild cousins.
  • Haeckel placed bacteria within the Kingdom Protista in a separate group that he called Monera, recognizing that these organisms differed from all other cells because they lacked nuclei. As biologists learned more about bacteria, they became aware of the further differences between these organisms and all other life forms. In addition to lacking nuclei, bacteria differ from other types of cells in that they do not have membrane-bound organelles, such as mitochondria, the cell structures involved in energy metabolism.
  • In 1938 American biologist Herbert Copeland argued that the distinctions between prokaryotes and eukaryotes were so fundamental that prokaryotes merited a fourth kingdom of their own called Kingdom Monera (now called Kingdom Prokaryotae).
  • In the 1950s, American biologist Robert H. Whittaker proposed adding a fifth kingdom, kingdom f, based on fungi’s unique method of obtaining food. Fungi had previously been classified with plants, but Whittaker argued that fungi do not make their own food, as plants do, and they do not ingest it, as animals do. Rather, fungi secrete digestive enzymes around their food, breaking it down before absorbing it into their cells.
  • Cord woese gave six kingdom classification, by adding Archaea as another category.

Importance of Classification

l    Classification makes the study of a wide variety of organisms easy. Classification is the tool by which one can deal with great diversity of living forms.

l    Classification projects before us a picture of all life forms at a glance.

l    Classification is essential to understand the interrelationships among different groups of organisms.

l    Classification forms a base for the development of other biological sciences.

Artificial System of Classification

It is a system of classification, which uses one or two morphological characters for grouping of organisms. Some artificial system have used habit and habitat for this purpose. Pliny the Elder (23—79 AD.) applied artificial system of classification to both plants and animals. This classification divided plants and animals into land, air and water. Pliny distinguished animals into flight and non-flight ones. Flight animals included bats, birds and insects.

This system has several drawbacks

l       It does not study homology but is mostly based on convergence.

l    The system employs one or two morphological and ecological traits which have no bearing on the actual status of taxa.

l    The characters picked up for artificial system of classification, show progressive, retrogressive or parallel evolution. Therefore, they do not reflect any natural relationship.

l    Organisms of close affinities get separated into different groups, e.g., bat, whale and rat or Solanum tuberosum  (herb). Solanum jasminoides (climber) and Solanum grandiflorum (a tree).

 

Natural System of Classification

It is a system of classification which takes into consideration comparable study of a number of characters so as to bring out natural similarities and dissimilarities and hence natural relationships among the organisms. The system employs those characters which are relatively constant. They include morphological characters, anatomical characters, cytological characters, physiology, ontogeny or development, reproduction, cytochemistry and biochemistry. In this system homology is brought out through the study of internal and external characters. Homology is the relationship of comparable structure.

Natural system of classification is certainly better than any artificial system of classification because

l       There is stress on actual study of each and every organism.

l       There is stress on comparative study.

l    Helps in identification of an organism.

l       It brings about affinities on the basis of a number of characters.

l       It places only related organisms in a group.

Nomenclature

The adoption of a system of binomial system of nomenclature is due to Swedish botanist and physician Carolus Linnaeus (1707–1778) who attempted to describe the entire known natural world and gave every species (plants or animal) a two-part name. However, binomial nomenclature in various forms existed before Linnaeus, and was used by the Bauhins, who lived nearly two hundred years before Linnaeus.

The value of the binomial nomenclature system derives primarily from its economy, its widespread use, and the stability of names it generally favors:

l    Every species can be unambiguously identified with just two words.

l    The same name can be used all over the world, in all languages, avoiding difficulties of translation.

l    The genus name and species descriptor may come from any source whatsoever. Often they are Latin words, but they may also come from Ancient Greek, from a place, from a person (preferably a naturalist), a name from a local language, etc.

However, names are always treated grammatically as if they were a Latin sentence. For this reason the name of a species is sometimes called its “Latin name,” although this terminology is frowned upon by biologists (and philologists), who prefer the phrase scientific name.

The scientific names are unique, understood and followed all over the world. They are not changed easily. They are guided by a set of rules stated in the International Code of Biological Nomenclature.

Categories of Classification

Living organisms are first split into kingdoms, such as the animal and plant kingdoms. These kingdoms are then split up into a large number of smaller groups called phyla (singular : phylum). All the members of the phylum have certain things in common. Each phylum is divided into classes, classes into orders, orders into families, families into genera (singular : genus), and genera into species.

Taxa Potato Wheat Paramecium Man
Scientific name Solanum tuberosum Triticum aestivum Paramecium caudatum Homo sapiens
Kingdom Plantae Plantae Animalia Animalia
Phylum/Division Spermatophyta Spermatophyta Protozoa Chordata
Subphylum/Subdivision Angiospermae Angiospermae Ciliophora Vertebrata
Class Dicotyledonae Monocotyledonae Ciliata Mammalia
Order Polemoniales Germinales Holotricha Primates
Family Solanaceae Gramineae   Hominidae
Genus Solanum Triticum Paramecium Homo
Species tuberosum aestivum caudatum sapiens

It is important to note that the species is the basic level of all modern classification. The species is an isolated reproductive unit which does not mate with members of other reproductive isolates. Thus, species is most unambiguous of all taxa in the hierarchy. A species is a group of organisms that are able to breed together and produce fertile offspring. For example, human beings, dogs, cats, etc., form distinct species. But when a horse (Equus cabalus) and Ass (Equus asinus) belonging to different species interbreed, the product is the mule which is sterile, i.e., incapable of reproducing.

Classification of Plants

Plants exhibit tremendous diversity in size, form, colour, organization, distribution and life history. The chart given below briefly outline the basis for their classification.

Plant kingdom (Kingdom Plantae). According to Eicheler (1883) plant kingdom is subdivided into two subkingdoms : Cryptogames and Phanerogames (Spermophyta)

 

Sub-Kingdom Cryptogames (Gr. Crypto-hidden; gamous-marriage)

This subgroup of plant kingdom comprises “lower plants” “flowerless” or “seedless” plants. These plants do not bear external flowers or seeds and hence are considered to have hidden reproductive organs. They reproduce by spores. This sub-group includes three divisions Thallophyta, Bryophyta and Pteridophyta.

 

Division Thallophyta (Gr. Thallus – plant body without root, stem and leaves; phyton – a plant)

Have the simplest plants which possesses undifferentiated or thallus like forms, single celled nonjacketed reproductive organs and a mode of development devoid of an embryo stage. Vascular tissues are absent.

l     Most primitive and simple plants. The plant body is not differentiated into stem, root and leaves, but it is in the form of an undivided thallus.

l     Asexual reproduction generally takes place by spores.

l     Sex organs are simple, single-celled and there is no embryo formation after fertilization.

l     In their life-cycle, the gamete-producing haploid phase, called gametophytic phase is dominant. The short spore-bearing diploid phase, the sporophytic phase, does not remain attached to the gametophyte.

The division Thallophyta is divided into three classes : Algae, Fungi, Lichens.

Algae (L., alga – sea weed)

l     Most algae are water-growing or aquatic, both marine and fresh water; some are terrestrial, i.e., live on land near moist places.

l     Usually contain green pigment for photosynthesis; some algae have other photosynthetic pigments such as red, brown, blue, green and purple. These pigments form the basis of further classification of algae.

l     They are autotrophic, i.e., manufacture their own food. Reserve food is generally starch.

l     They have a cellulose cell wall around their cells.

l     The plant body may be unicellular (Chlamydomonas), colonial (Volvox), filamentous (Ulothrix, Spirogyra, Oedogonium or with large thallus Laminaria, Ficus, Sargassum).

  • Examples : Blue-green algae (Nostoc, anabaena); diatoms; red algae (Batra chospermum, Polysiphonia); brown algae (Laminaria, Fucus, Sargassum) and green algae (Acetabularia, Ulothrix, Spirogyra, Oedogonium, Chlorella, Chlamydomonas, Pandorina, Volvox).
  • Fungi (L., fungus – a mushroom)
  • Simple non-green plants which are not photosynthetic. They are heterotrophic. Some fungi, such as Puccinia, Albugo, Ustilago, etc., are parasites, drawing their nutrients from the living cells of their host-plants. Some fungi, such as Mucor, Rhizopus, Penicillium and Agaricus, are saprophytes, deriving their nourishment from the dead remains of plants and animals.
  • They may be unicellular (yeast) or filamentous (most fungi). The body of a multicellular and filamentous fungus is called a mycelium and is composed of several thread-like structures, termed hyphae.
  • Fungi have a cell wall containing a mixture of chitin and cellulose.
  • The reserve food is glycogen.

 

Examples : Slime mold; bread mold (Rhizopus) Mucor; yeast; pink bread mold (Neurospora); brewer’s yeast (Penicillium; cup fungus (Peiziza); sponge fungus (Morchella)`1; mushroom (Agaricus); rust (Puccinia); smut (Ustilago) and Aspergillus.

 

Differences between Algae and Fungi

Fungi Algae
l    Fungi always live in contact with organic matter l       Algae occur freely.
l    Fungi, live in aquatic, subaquatic and terrestrial habitats. l    Algae do not occur in terrestrial habitats. They are aquatic or subaquatic.
l    Fungi lack chlorophyll l    Algae usually posses chlorophyll
l    Motile spores (Zoospores) and motile gametes are rare. l    Motile spores and motile gametes are quite common.
l    In higher forms, karyogamy is delayed after completion of plasmogamy. l    Plasmogamy is immediately followed by karyogamy.
l    There is progressive reduction of sexuality in fungi. l    There is progressive evolution of sex amongst algae.

Lichens

l    Lichens grow on rocks, tree-trunks, and even on the ground. They are very hardy.

l    In lichens, algae and fungi live in symbiosis, (mutualism), i.e., they co-exist for mutual benefit.

l    The algae component of the lichen is known as phycobiont and the fungal component as mycobiont.

l    The fungus absorbs water and mineral matter and supplies it to the algae. The algae, in turn, prepares food and supplies it to the fungus.

Examples : Crustose lichens foliase lichens (e.g., Parmelia, Collema) and fruticose lichens (e.g., Alectoria, Usnea)

Division Bryophyta

l    They have over 25,0000 species.

l    The dominant phase or plant body is a free living gametophyte.

l    Bryophytes are small multicellular green land plants. These simplest land plants are confined to shady damp places. They are also called amphibians of the plant kingdom.

l    Their plant body is a flat, green thallus in liverworts (Riccia, Marchantia) and leafy, erect structures in mosses (Funaria, Sphagnum). They lack true roots, stems and leaves and have no flower.

l    In them a true vascular system is absent.

l    Gametophyte is attached to substratum by means of hair-like outgrowths, the rhizoids which absorb water and minerals from the substratum.

l    The sex organs are multicellular.

l    An embryo is formed upon fertilization.

Examples : Riccia, Marchantia, Anthoceros, Funaria, Barbula.

 

Division Pteridophyta

l    Dominant phase or plant body is a sporophyte.

l    Plant body is differentiated into true stem, leaves and roots.

l    They are found mainly in shady or damp places.

l    They have well developed vascular system (xylem and phloem).

l    These plants have no flowers and do not produce seeds.

l    Sex organs are multicellular and jacketed by sterile cells.

l    Fertilised egg develops into embryo.

l    Embryo stage is present.

Examples : Club mosses – Selaginella, Lycopodium (“ground pine”); horsetails – Equisetum; and ferns – Marsilea, Azolla, Adiantum, Dryopteris, Pteris and Pteridium.

Sub-Kingdom-Phanerogames or Sprematophyta (Gr. Sperma,– atos – seed)

l    They comprise over 250,000 vascular plants.

l    The plant body belongs to sporophytic generation.

l    The sporophytic plant body is differentiated into true stem, leaves and roots.

l    Phanerogames includes higher plants that bear flowers and seeds.

l    The plant body is differentiated into root, stem and leaves.

l    Vascular system (xylem and phloem) well developed.

l    Sex organs are multicellular.

l    An embryo develops from fertilized egg.

On the basis of absence or presence of fruits, the group of seed bearing plants is further divided into two subdivisions : Gymnospermae and Angiospermae.

Subdivision Gymnospermae (Gr., gymno – naked; sperma – seed)

l    They are most primitive and simple seed plants.

l    The seeds produced by these plants are naked and are not enclosed within fruits.

Gymnospermae includes the following two groups :

l    Cycadae. e.g., Cycas, etc.

l    Coniferae. e.g., Pinus, Cedrus, Ginkgo, etc.

Subdivision Angiospermae (Gr., angeion – case; sperma – seed)

l    Angiosperms are highly evolved plants and they produce seeds that are enclosed within the fruit.

l    The reproductive organs are aggregated in a flower.

On the basis of the number of cotyledons (fleshy embryonic leaves), the angiosperms are divided into two groups : dicotyledons and monocotyledons.

Dicotyledonae (Dicots)

l    The seeds produced by these plants have embryos with two fleshy leaves, the cotyledons.

l    Their leaves have reticulate venation, with a network of veins.

l    The root system has a prominent tap root.

l    The flowers have five or multiple of five petals.

l    The vascular bundles are arranged in a ring. They are open (i.e., have cambium) and undergo secondary growth.

Examples : Pea (Pisum sativum), potato (Solanum tuberosum), sunflower (Helianthus annuus), rose (Rosa indica), banyan (Ficus religiosa), neem (Melia indica), apple (Malus silvestris).

Monocotyledonae (Monocot)

l    The seeds of these plants have only one cotyledon.

l    Their leaves have parallel venation.

l    The root system consists of similar fibrous roots.

l    The flowers are trimerous, i.e., have three or multiple of three petals.

l    The vascular bundles are scattered and closed (i.e., lack cambium). Secondary growth does not occur.

Examples : Maize (Zea mays), wheat (Triticum vulgare), rice (Oryza sativa), onion (Allium cepa), sugarcane (Saccharum officinarum), barley (Hordeum vulgare), banana (Pandanus), Coconut and grasses.

      Classification of Animals

l    Animals are the most diverse groups of organisms, with more than a million living species.

l    Multicellular heterotrophs, designated as Metazoa sub-divided into Parazoa and Eumetazoa.

l    Characterised by mobility, sensory and nervous systems.

l    Parazoa (sponges) lack these features, hence were considered as plants initially.

l    Animal life arose from the ocean depth, but now are found in all habitats.

l    The mode of life, feeding and movement has influenced the anatomy physiology and
behaviour of animals to a great extent.

Animal body construction plan

l    There are three basic plans on which animal body are built.

l    Cell-aggregate plan

l    Blind-sac plan

l    Tube-within-tube plan.

Cell-aggregate plan

l    Body is simply formed by aggregation of cells representing initial stage of multicellularity, but cellular grade of organization, tissue level is absent.

l    The cells are of different types but showing only rudimentary  division of labour  and without nervous coordination e.g., sponges.

Blind-sac plan

l    Comparatively more complex organisation with tissue grade of organisation.

l    Body is closed tube-like with only one opening through which ingestion of food and the egestion of undigested waste occur.

l    Cells are more specialized showing actual division of labour with nervous coordination achieved.

Figure 3. 1 Plan of animal construction

Tube-within-tube Plan

l    The highest grade of architectural plan that exists in all triploblastic animals, i.e., from phylum platyhelminthes to chordata.

l    The body wall makes the outer large (ectodermal) and the inner tube  alimentary canal (gut) with openings at both ends. The cavity between body wall and gut is coelom.

Figure 3. 2 Types of body cavities in animal

l    The alimentary canal opening of gut is formed in two ways during embryonic development, which represents the two evolutionary lines : (1) Protostomia and (2) Deuterostomia.

Protostomes 

In these animals mouth is formed first i.e., at the site of blastopore and the anus develops
later. Examples: Annelids, Molluscs and Arthropods.

Deuterostomes

Here anus is formed first, at the site of blastopore and mouth develops later at its opposite
end. Examples: Echinoderms and Chordates.

BODY SYMMETRY

Body shape is 3-dimensional hence has a particular symmetry. It is an imaginary line along which the shape of the body is determined.

It is of three types :

l    Radial

l    Bilateral

l    Asymmetric symmetry.

 

Radial Symmetry

When the body can be divided in two equal parts on any plane. This is most primitive type
found in early animals like sponges, coelenterates and adult echinoderms (though advance group).

Bilateral Symmetry

In most animals, body can be divided into two equal halves on only one plane, hence body has left and right sides front and rear (back) sides; anterior and posterior ends; dorsal and ventral sides.

Asymmetric Type

In many animals the body can not be divided in two equal halves on any plane. Ex. Amoeba being irregular in shape, some sponges with various branching. Gastropod molluscs (snails, conch) have no symmetry due to torsion in embryonic stage.

BODY CAVITY (COELOM)

l    A true coelom is defined as the cavity between body wall and alimentary canal lined with
mesodermal epithelia on both sides. It is the part of triploblastic body with ‘tube-within-tube’ plan.

l    This allows greater body flexibility, accommodates various organs and also provides hydrostatic skeleton.

Figure 3. 3 Structure of Coelom

Pseudocoel

In Nemathelminthes, the coelom arises from embryonic blastocoel and has only body wall side lined with mesoderm.

Haemocoel

In Arthropods the coelom is reduced and becomes a blood-filled cavity hence termed as haemocoel.

Enterocoel

When the coelom develops as the lateral pouches of the gut. Ex. Echinoderm, Chordates.

Schizocoel

The coelom formed by split in the mesodermal mass of cells. This enlarge as cavities Ex. Annelida, Arthropoda, Helminthes.

Body Segmentation

In many animals body is divided into segments. This is significant from structural and evolutionary points of views. This is of two types :

Metameric segmentation (Metamerisation)

l    This is true segmentation which occurs during the embryonic development.

l    Each segment is in sequence with its preceeding and succeeding segments, hence represents
a definite position. Ex. Annelids, Arthropods, Chordates.

l    In Arthropods each segment bears paired appendages which are sensory (antenna),
locomotory (legs) and feeding (mouth parts) apparatus. Segments also become grouped
to form body regions like head, thorax and abdomen.

Pseudometamerisation

l    This is false segmentation which doesn’t occur in embryonic stage e.g., tape worms.

l    The segments are formed continuously one behind another in adult throughout the life.

l    Each segment is individually independent; the older reaching the posterior end and newer
being formed at the anterior end.

BODY SUPPORT AND PROTECTION

l    Bodies of animals are invariably supported with hard structures to provide protection shape and strength. This is called skeleton.

l    The hardness is provided by minerals (inorganic substance) and some special organic substances like proteins.

l    Its varieties and complexity have progressed with the grade of evolution.

l    Primitive animals are without hard support or covering e.g., coelenterates and worms.

Exoskeleton

l   The external covering formed by the deposition or secretion of hard protective material.

l   Cuticle of arthropods is unique gift of nature to them which make them able to survive in all odd conditions being resistant to air, temperature, water and other chemicals; it forms wings, surface for muscle attachment, etc.

l   Molluscs have hard calcareous shell.

l   Echinoderms have both calcareous and cartilaginous plates below the skin.

l   Vertebrates have scales, feathers, claws, hairs, nails, etc.

 

Endoskeleton

l   Cuticle also forms endoskeleton in Arthropods.

l   In vertebrates these are bones and cartilages.

l   Providing surface for attachment of muscle it provides greater opportunity for movement and
speed.

Like the woody vascular system led to the evolution of large plants, the endoskeleton has lobed by vertebrates attaining large size.

  1. PHYLUM-PROTOZOA (Gr., protos – first; zoon – animals; early animals)

l    Unicellular (one-celled or single-celled), mostly aquatic (fresh water or marine) animals.

l    Solitary or colonial, free living or parasitic or symbiotic.

l    Body naked or covered by pellicle or hard shells.

l    Body shape may be irregular, spherical, oval, elongated or flattened.

l    Cytoplasm differentiated into outer ectoplasm and inner endoplasm.

l    Uninuclete, binucleate or multinucleate.

l    Locomotion by finger-like pseudopodia, flagella or cilia.

l    Nutrition is mostly heterotrophic.

l    Asexual reproduction by binary fission, multiple fission, and sexual reproduction by conjugation.

Phylum protozoa is divided into the following five classes :

Mastigophora

l    Locomotory organs are flagella.

Examples : Euglena, Noctiluca, Trypanosoma (causes sleeping sickness), Giardia (causes dysentery), Leishmania (causes kala azar)

Sarcodina (Rhizopoda)

l    Pseudopodia are chief organelles of locomotion and food catching.

Examples : Amoeba, Entamoeba (causes dysentery), Polystomella, Arcella

Sporozoa

l    Lack locomotary organelles.

l    All are parasites.

Examples : Plasmodium (causes malaria), Monocystis.

Ciliata

Cilia are the chief locomotory and food catching organelles.

Examples : Paramecium, Opalina, Nyctotherus, Vorticella.

Suctoria

Adult without any locomotory organelles.

Examples : Ephelota.

2.   PHYLUM PORIFERA (Gr., porus – pore; ferre – to bear; sponges)

l    Sessile (stalk-less), sedentary (attached to the substratum), and marine except one group that lives in fresh water.

l    Simplest multicellular, diploblastic animals.

l    Have organization at cellular colony level. Thus, cells are loosely held together and do not form tissues.

l    Asymmetrical or radially symmetrical. Sponges may be vase-like, rounded, sac-like or branched.

l    Body is perforated by numerous pores, the ostia that open into a canal system having canals and chambers lined with collared flagellated cells or choanocytes. It also has one or more large-sized outlets for water, called oscula (singular osculum). Water brings food and oxygen.

l    Mouth, digestive cavity and anus absent.

l    Skeleton is made up of minute calcerous or silicious spicules or spongin fibre or both. Possess great power of regeneration.

Phylum porifera is divided into the following three classes :

Calcarea.

l    Marine.

Examples : Leucosolenia, Sycon (Scypha).

Hexactinellida.

l    Marine

Example : Euplectella (Venus’s flower basket), Hyalonema (rope sponge)

Demospongiae. Mostly marine and a few fresh water solitary or colonial form.

      Example : Cliona (boring sponge), Spongilla, Euspongia (bath sponge)

  1. PHYLUM CNIDARIA OR COELENTERATA (Gr., koilos – hollow; enteron – gut)

l    Aquatic, mostly marine, a few such as Hydra are fresh water solitary or colonial forms.

l    Cnidarinas or coelenterates are multicellular, diploblastic animals with tissue grade of organization.

l    Body shows radial symmetry.

l    A central gastrovascular cavity coelenteron is present which lacks anus but has mouth which is surrounded by short and slender tentacles.

l    Possess specialized cells (cnidoblasts) bearing stinging organoids called nematocysts. Nematocysts serve the functions of paralyzing the prey by injecting poison or to hold the prey.

l    Respiratory, circulatory and excretory organs absent.

l    Nervous system is primitive, has only network of nerve cells.

l    Exhibit the phenomenon of polymorphism (Gr. Poly-many; morphe – shape) which is the specialization of individuals of a colonial species for the division of labour. For example, hydrozoans have feeding individuals or zooids, the gastrozooids, protective zooids, the dectylozooids and reproductive zooids, the gonozooids producing sexual medusae.

l    Body shows two main forms, the polyps and the medusae. The polyp is diploid, cylindrical and sedentary. It is either solitary or colonial and reproduces asexually. The medusa is diploid, umbrella-like and free-swimming sexual phase of the animal.

l    Asexual reproduction by budding and sexual reproduction by gametes formed by medusae.

l    Many forms possess a hard exoskeleton of lime to form corals.

Phylum coelenterata is divided into the following three classes :

Hydrozoa.

      Their life history includes both polypoid and medusoid forms.

Example : Hydra, Obelia, Millepora (coral), Physalia (Portugese man of war), Porpita.

Scyphozoa.

      Their life history lacks polypoid phase and has only medusoid form.

Examples : Aurelia (jelly-fish), Rhizostoma.

Anthozoa.

      Their life history has only polypoid form, the medusoid forms are absent.

Examples : Pennatula (sea-pen), Tubipora (organ pipe coral), Gorgonia (sea-fan), Corallium (red coral), Metridium (sea anemone), Fungia (mushroom coral).

  1. PHYLUM-CTENOPHORA (Gr., ktenos – comb; phora – carrying)

l    Transparent body with biradial symmetry.

l    Two tentacles and eight longitudinal rows of ciliary comb-plates for locomotion are present.

l    Marine solitary and free-swimming.

Examples : Pleurobrachia (comb jelly), Cestum (Venus’s girdle), Ctenoplana, Beroe (sea mitres).

  1. PHYLUM-PLATYHELMINTHES (Gr., platys – flat; helmins – worm; Flatworms)

l    Bilaterally symmetrical and dorsoventrally flattened animals.

l    Body thin, soft, leaf-like, ribbon-like.

l    They are first triploblastic animals which means their tissues differentiate from three embryonic germ layers. They are without a body cavity (acoelomate animals).

l    Digestive cavity (when present) with a single opening, the mouth (anus is absent).

l    Suckers and hooks are usually present.

l    Circulatory, respiratory and skeleton systems are absent.

l    Excretory system consists of blind tubules called protonephridia. Blind end bears a tuft of cilia or a flagellum and is called a flame bulb or flame cell.

l    Hermaphrodite, i.e., both male and female reproductive organs occur in the same individual.

l    The turbellarians are free-living, aquatic, both marine and fresh water and a few are terrestrial. Trematodes and cestodes are parasitic.

Examples: TurbellariaDugesia, Planaria

TrematodaFasciola (liver fluke), Schistosoma (blood-fluke);

CestodaTaenia solium (pork tape-worm).

6.   PHYLUM-ASCHELMINTHES (Gr., ascus – a bladder; helminis – worm; Round worm)

l    Bilaterally symmetrical, triploblastic, pseudocoelomate and unsegmented animals.

l    Body worm-like (i.e., round, slender and tapering at the two ends), cylindrical or flattened.

l    Body is covered with a tough, resistant cuticle; cilia absent.

l    Alimentary canal straight and complete with mouth and anus; pharynx muscular.

l    Sexes are separate.

l    Most forms are parasitic but some are free-living in soil or water.

Examples : Ascaris (round-worm), Ancylostoma (hook-worm), Wucheria (filarial worm), Enterobius (pinworm of man).

 

7.    PHYLUM-ANNELIDA (L., annelus – a ring;        segmented worms)

·               Body triploblastic, bilaterally symmetrical, soft, elongated, vermiform and cylindrical or dorsoventrally flattened.

·               Body is metamerically segmented externally by transverse grooves and internally by septa. Some of the anterior body segments concentrate to form head.

·               Exoskeleton absent; body is covered by a thin cuticle.

·               Locomotory organs are segmentally arranged paired lateral appendages, parapodia or chitinous setae or chaete.

  • Alimentary canal is tube-like, complete and extends straight from mouth to anus.
  • True coelomatic animals (first animals with true body cavity) with closed blood vascular system.
  • Excretion by paired segmental nephridia which removes wastes from coelom and blood stream directly to the exterior.
  • The nervous system consists of a dorsal “brain” and a ventral nerve cord having ganglia and lateral nerves in each body segment.
  • Reproduction is by sexual means. Sexes may be united (hermaphroditic) or separate.
  • Mostly aquatic, marine or fresh water; some are terrestrial (in moist soil), burrowing in tubes, some free-living forms.

Phylum Annelida includes the following three classes :

Polychaeta. Locomotion by segmentally arranged parapodia having numerous setae.

Examples : Nereis (calm worm or sand worm), Aphrodite (sea mouse)

Oligochaeta. Body without distinct head and lacks eyes, tentacles and parapodia.

Examples : Pheretima (earthworm), Eutypheus, Lumbricus.

Hirudinea. (1) Body with anterior and posterior suckers.  (2) Parapoda and setae are absent.

Examples : Hirudinaria (Indian cattle leech). Pontobdella.

8.   PHYLUM-ARTHROPODA

      (Gr., arthros – jointed; podos – foot; Animals with jointed feet)

l    Triploblastic, bilaterally symmetrical and metamerically segmented animals.

l    Body segments are grouped into two regions – cephalothorax (head and thorax together) and abdomen, or three regions – head, thorax and abdomen. Anterior part of body forms a distinct head, bearing sense organs and brain.

l    Body is covered with a thick chitinous (made of hard substance called chitin) and jointed exoskeleton which is moulted at intervals.

l    Each body segment usually bears laterally paired and jointed legs or appendages.

l    Body cavity is haemocoel (i.e., filled with blood). The true coeloms reduced to the spaces of the genital and excretory organs.

l    Alimentary canal is complete, mouth and anus lie at opposite ends of the body.

l    Respiration through general body surface, by gills, air tubes (tracheae) or book-lungs.

l    Circulatory system is open with dorsal heart and arteries but without capillaries and veins.

l    True nephridia absent. Excretion by coelomoducts, malphighian tubules or green or coxal glands.

l    Sexes are usually separate; sexual dimorphism well marked in several forms.

l    Terrestrial or aquatic (fresh water and marine), free-living, commensal or parasitic (on other animals and plants) forms.

l    Arthropoda forms the largest phylum of animal kingdom. About 900,000 species are known.

Phylum Arthropoda is divided into the following five classes :

Class 1. Onychophora. Body elongated, segmented and is covered with thin cuticle.

Example : Peripatus.

      Class 2. Crustacea. 1. Head and thorax fused together to form cephalothorax. 2. Respiration by gills.

Example : Palaemon (prawn), Daphnia (water flea),  Cyclops (one-eyed giant), Cancer (true crab).

      Class 3. Myriapoda. 1. Body elongated, metamerically segmented, each segment with one or two pairs of legs. 2. Respiration by tracheae.

Examples : Scolopendra (centipede), Julus (milepede).

      Class 4. Insecta. 1. Body divisible into distinct head, thorax and abdomen. 2. Abdomen lacks appendages, head with a pair of antennae and mouth parts and thorax with three pairs of legs and two pairs of wings. 3. Respiration by tracheae.

Examples : Lepisma (silver fish), Melanopus (grasshopper), Gryllus (house cricket), Periplaneta (cockroach), Musca (house fly), Apis (honey bee), Anopheles (mosquito), Culex (mosquito), Pieries (butterfly), Cimex (bed bug).

Class 5. Arachnida. 1. Body divisible into cephalothorax and abdomen. 2. Antennae and true jaws absent. 3. Respiration by tracheae, book-lungs or book gills.

Examples : Limulus (king-crab), Palamnaeus (scorpion); Aranea (spider), Sarcoptes (itchmites), Argus (tick).

9.   PHYLUM-MOLLUSCA (L., molluscus – soft)

l    Body soft, unsegmented, bilaterally symmetrical and without appendages. The size of body varies from a microscopic to a giant form such as Octopus of up to 50 feet.

l    Body is divisible into an anterior head, a ventral muscular foot, a hard dorsal visceral mass. The entire body is covered by a fold of thin skin, called mantle which secretes a hard calcareous shell of one or more pieces.

l    Body cavity is haemocoel. True coelom is restricted to the pericardial cavity and the lumen of the gonads and nephridia.

l    Digestive tract simple.

l    Respiration by gills (called ctenidia), mantle or a “lung” of the mantle.

l    Circulatory system is open except in cephalopods.

l    Excretion by a pair of metanephridia or kidneys.

l    Sexes are usually separate.

l    Aquatic, mostly marine, few fresh water and some terrestrial forms.

The phylum mollusca is divided into the following five main classes :

      Class 1. Polyplacophora. 1. Shell composed of eight calcareous pieces.

Example : Chiton.

      Class 2. Gastropoda. Univalve shell and visceral mass are spirally coiled (torsion).

Examples : Pila (apple snail), Aplysia (sea hare), Helix (garden snail).

      Class 3. Scaphopoda. Tusk-like tubular shell opens at both ends.

Examples : Dentalium (tusk shell).

      Class 4. Pelecypoda (Bivalvia). Shell consists of two lateral valves hinged together middorsally.

Examples : Unio (fresh water mussel), Pinctada (Indian pearl oyster), Teredo (ship worm).

      Class 5. Cephalopoda. 1. Shell external, internal or absent. 2. Foot altered into a series of sucker-bearing arms or tentacles.

Examples : Nautilus, Loligo, Sepia, (Cuttle-fish), Octopus (devil fish).

10. PHYLUM-ECHINODERMATA (Gr., echinos – spiny; derma – skin; spiny skinned animals)

l    Simple animals may be star-like, spherical or elongate.

l    Body triploblastic, coelomate, unsegmented and radially symmetrical (larva bilaterally symmetrical)

l    Body lacks head, but has oral and aboral surfaces. Oral surface of body has five radial areas called ambulacra.

l    Body wall is covered by spiny calcareous plates forming a rigid or flexible endoskeleton.

l    Body cavity is modified into a unique water vascular system which moves respiratory and locomotary organs, the tube feet or podia.

l    Excretory organs absent.

l    Reproduction sexual, asexual or by regeneration. Sexes are separate.

l    Exclusively marine, gregarious (live in groups) living.

Phylum echinodermata includes the following five classes :

      Class 1. Crinoidea. The oral surface is directed upward.

Example : Antedon (feather star).

      Class 2. Holothuroidea.      1. Worm-like body without arms and spines.

  1. Mouth surrounded by tentacles.

Example : Holothuria (sea cucumber).

      Class 3. Echinoidea. 1. Spherical or discoidal body lacking arms. 2. Body enclosed in an endoskeletal shell or test a closely fitted calcareous plates covered with movable spines.

Examples : Echinus (sea urchin).

      Class 4. Asteroidea. Flattened, pentagonal or star-shaped body with flexible endoskeleton.

Examples : Pentaceros, Asterias (star fish).

      Class 5. Ophiuroidea. Asteroids-like body is flat and composed of long arms and a central disc.

Examples : Ophioderma (brittle star), Ophiura (brittle star).

 

  1. PHYLUM: CHORDATA
  • Notochord (chorda dorsalis) present at some stage in the life.
  • In vertebrates the notochord is replaced by bony vertebral column.
  • Paired pharyngeal visceral gill slits.
  • Dorsal, single and hollow (tubular) nerve cord.
  • Post anal tail is present.
  • Segmented muscle blocks (myotomes) on either side of the body.
  • Blood flows forward in ventral vessel and backwardly in dorsal vessel.
  • Ventral myogenic heart is made of cardiac muscle.
  • Divided into two groups: (1) Acraniata (2) Craniata.

Group I: Protochordata (Acraniata)

l    Some groups possess the chordate characters only partially, hence are grouped as protochordata,

l    They are without cranium (acrania)

Divided in three sub-phyla:  (I) Hemichordata (II) Urochordata and (III) Cephalochordata.

Hemichordata

l    Now preferred to be kept as non-chordate phylum.

l    Body worm-like, divided into proboscis, collar and trunk.

l    Buccal diverticulum which was earlier thought to be the rudiment of notochord is a simple
epidermal thickening of ectodermal origin.

l    Several pairs of gill slits in branchial part of trunk with two lateral folds.

l    Skin with only epidermal layer.

 

Figure 3. 4  Balanoglossus A. Adult,  B. Tornaria larva

l    Sexes are separate, ovaries and testes are arranged in double rounds along the most part of the trunk, fertilization is external.

l    Development indirect, through tornaria larva which resembles bipinnaria larva of echinoderm.

l    Mostly tubiculous and marine.

Ex. Balanoglossus (acorn worm or tongue worm), Saccoglossus.

Urochordata

l    No trace of notochord, and nerve cord in adult
stage.

l    Adult is a sessile filter feeder. It is degenerated
compared to larva (tadpole).

l    This shows retrogressive metamorphosis.

l    Larva possesses notochord, tubular nerve in tail
part only.

l    Also called as tunicata because the body
covering (tunic or test) is made of tunicin, a
cellulose like substance.

Ex. Herdmania (sea squirt), Doliolum; Salpa, Pyrosoma (bioluminiscent).

Figure 3. 5 Herdmania

Cephalochordata (Branchiostomata)

l    Notochord in entire length of body, extended upto head in both adult and larval forms.

l    Fish like animals with median fins, without distinct head and limbs.

l    Filter feeder, feed upon micro-organism.

l    Wheel organ is present for creating water current in front of mouth.

l    The oral hood dorsally covers the mouth.

l    Brain absent but the oral nerve ring is present.

l    Ammocoete larva comes in life cycle.

Ex. Amphioxus or Branchiostoma (lancelets).

Group II: Vertebrata or Craniata

l    It is also known as euchordates.

l    Notochord replaced by vertebral column.

l    Cranium (brain box) well formed with brain.

l    Divided in two sub groups: (I) Agnatha and (II) Gnathostomata

Agnatha

l    The jawless, most primitive chrodates

l    Constituting single class.

Class: Ostracoderms

l    All extinct vertebrates.

Ex. Cephalaspis.

Class: Cyclostomata

l    Mostly sanguivorous, eel-like.

l    Mouth jawless, suctorial and round.

Figure 3. 6 Petromyzon

l    Single, median nostril, a median eye and pair of true eye without eyelids.

l    Remain as ectoparasite on fishes as blood sucker.

l    No paired fins and lateral line systems.

l    Most of life the adult lives in sea but are well adapted to live in fresh water for breeding.

l    Ammocoete larva comes in life cycle.

Ex. Petromyzon (lamprey), Lampetra (lamprey ectoparasites on sharks), Myxine (hag fish).

Gnathostomata

l    Mainly free living forms; jaws encircle mouth.

l    3 semicircular canals in internal ear.

l    Paired lateral fins or limbs, pectoral and pelvic girdles are present for movement

l    Divided into two super classes: (i) Pisces (ii) Tetrapoda

Super Class:  Pisces (fishes)

l    All are aquatic with branchial (gill) respiration and paired lateral fins with girdles.

l    Two chambered venous heart, with sinus venosus and truncus arteriosus well developed

l    No perception of air borne sound. Only internal ear present, no middle and external ear.

l    Eye without eyelid. Highly developed sense of smell (olfactory lobe in brain is larger)

l    Lateral line system serves, as special sensory system for balancing, perceptions of vibration     and electric field.

l    Mostly ammonotellic, but some marine bony fishes excrete trimethyl ammomium oxide (TMO)

l    Egg macrolecithal type, no Fertilization external larval stage. It is further divisible into three classes on the basis of skeleton: Class (i) Chondrichthyes (cartilaginous fishes), (ii) Placodermi (the ancestral fishes with plate like body covering all extinct) and (iii) Osteichthyes (bony fishes)

Comparable features of cartilapinous and bony fishes          

Chondrichthyes (cartilaginous fish) Osteichthyes (bony fishes)
–          About 600 species

–          Exclusively marine

–          Mouth ventral behind snout

–          All 5 pairs gill slits open to outside separately, no operculum

 

–          Scroll valve (spiral) in small intestine

–          Scales of placoid type

–          No swim bladder or air bladder

 

–   About 2,5,000 species

–    Both marine and fresh water

–    Mouth is always terminal.

–    All gill silts open together in a gill chamber with common opening outside covered by operculum.

–    No scroll valve is present

–    Scales of cycloid, ctenoid, ganoid types.

–    It is present above the gut. This is for buoyancy, specially in fresh water form.

Migratory fishes: Many fishes migrate regularly from one habitat to another. It is of following two types:

(a)  Anadromous: They move from sea to river e.g., Hilsa, Salmon.

(b)  Catadromous: They move from river to sea e.g., Anguilla.

Super Class:  Tetrapoda

l    For shifting from water to land vertebrates acquired some drastic changes like.

l    Pulmonary (lung) respiration two pairs of limbs (pentadactyle) present.

l   Internal fertilization except in amphibians.

l   Air borne sound perception and sound production (vocal)

Classified into four classes: (i) Amphibia (ii) Reptilia (iii) Aves (iv) Mammalia.

Class: Amphibia

l    Poikilothermic i.e., body temperature changes with environment.

l    Respiration by gills, skin, lung and buccal epithelium.

l    Scaleless and moist skin pervious to water.

l    Tooth homodont, acrodont and polyphyodont type.

l    Heart is 3 chambered (2 auricles and 1 ventricle), with sinus venosus and truncus arteriosus.

l    Renal portal system present; nucleated RBC

l    Gut, urinary duct and reproductive duct, open into cloaca.

l    10 pairs of cranial and spinal nerves each.

l    Development indirect through distinct larval stage called tadpole

l    Parental care well exhibited in various ways and forms.

Divided into 3 orders (living) : (i) Urodela, (ii) Anura (iii) Apoda

(A) Frog, (B) Bufo, (C) Tree frog, (D) Atyles

Ichthyophis

Figure 3. 7 Some examples of Amphibia

  l    Oviparous and direct development no larval stage.

l    Formation of 4 extra embryonic membranes amnion, chorion, allantois and yolk sac.

l    Due to presence of these membranes in reptiles, birds and mammals they are called amniotes.

Horned Toad

Tuatara

Naja naja

 
  Figure 3. 8 Some examples of Reptilia  

 

Class: Aves (Birds)

·               The most fascinating group of vertebrates includes about 9000 living species.

·               Most features are reptilian hence also called as glorified reptiles.

·               Homeothermic, highly evolved with highest rate of metabolism.

·               Body covered with soft feather (plumage) as modified scales of reptiles.

·               Scales are present on the legs.

·               Fore limbs modified as wings for flight.

·               Bipedal locomotion, hind limb modified for perching and walking.

·               High body temperature ranging from 42ºC to 45ºC.

·               4 chambered heart, with size of about 2% of the body i.e., double than mammal’s.

·               Only right systemic aorta present.

·               Uricotelic excretion helps in conservation of water.

·               Only left reproductive structures are functional (right one degenerated).

·               Sense of smell less developed, but vision is highly developed.

·               Bones pneumatic (with air space) hence are light but strong.

·               Oviparous, embryonic membranes all like reptiles.

  • High degree of parental care for young ones.
  • Many bird species possess instinct for seasonal migration. They migrate through long distances, generally for breeding in one region and for growing and feeding in the other.
  • Birds are known for their characteristic behaviour and have played companion to human in various fields like amusement, communication, hunting, beauty and aesthetics.
  • Highly evolved behaviours are like courtship, nestling, brooding (parental care), migration, etc.

 

 

Class: Mammalia

l    The homeotherms include more than 4,000 specis adapted also for aquatic, arboreal and aerial life.

l    Most primary features are the presence of hairs, pinna (external ear) and mammary gland.

l    Skin with sweat, gland and sebacious gland and their many modified glands.

l    Muscular diaphragm divides coelom as thoracic and abdominal cavities.

l    Only left systemic arch persists in adult.

l    RBC without nucleus (biconcave) except camel (oval)

l    3 ear ossicles (incus, malleus and stapes) present in the tympanic cavity.

l    Presence of 7 cervical vertebrae except few.

l    Eggs microlecithal or alecithal type.

l    Viviparous development and formation of placenta except prototherians.

Divided into three subclasses: (i) Prototheria, (ii) Metatheria and (iii) Eutheria

 

 

 

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exercise

 

Very Short Answer Questions

  1. Name a chondrichthyes fish with covered gills?
  2. How can you identify a poisonous frog?
  3. Which teeth are modified into tusks in elephants?
  4. Name an alga which is used in laboratory culture media?
  5. Name the four classes of pteridophytes.

Short Answer Questions

  1. Distinguish between crytogamae and phanerogamae.
  2. Differentiate between dicots and monocots.
  3. Why are bryophytes called plant amphibians.
  4. How bony fish are different from cartilaginous fish?
  5. Explain how birds have adapted themselves to an aerial mode of life.

 

Long Answer Questions

  1. Give the general characteristics of the vertebrates and list the distinguishing features of the classes under it.
  2. Write down the general characters of class mammalia?
  3. Classify the following animals. Petromyzon, African lung fish, cobra, whale, gorilla.
  4. Describe the important characteristics of gymnosperms.
  5. Explain the terms (a ) Gametophyte (b) Sporophyte (c) Alternation of Generations.

HOT Questions

  1. Why are living organisms classified?
  2. Why are the classification systems changing every now and then?
  3. What different criteria would you choose to classify people that you meet often?
  4. What do we learn from identification of individuals and populations?
  5. Given below is the scientific name of Mango. Identify the correctly written name.
  6. Define a taxon. Give some examples of taxa at different hierarchical levels.
  7. Can you specify the correct sequence of taxonomic categories?
  8. Define the following terms:

(a) Phylum (b) Class (c) Family (d) Order (e) Genus

  1. How is a key helpful in the identification and classification of an organism?
  2. Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.
  3. Who is said to be Father of Taxonomy?
  4. State the advantage of using scientific names instead of common or popular names?
  5. Who was the scientist to propose the binomial nomenclature? Give uses of this system?
  6. State the components of a scientific name?
  7. State the conventions followed while writing the scientific names?
  8. How are two characteristics to be used for developing a hierarchy in classification choose?
  9. State the basis for grouping organisms into five kingdoms?
  10. State the major divisions in the plantae. What is the basis for these division?
  11. State the criteria for deciding divisions in plants?
  12. How vertebrata are classified into further subgroups?

Very Short Answer Questions (1 Mark)

  1. What do you mean by diversity?
  2. Which division among plants has the simplest organisms?
  3. Name the plant which have two cotyledons.
  4. What are hermaphrodites?
  5. Name a fish with skeletal made up of bone.
  6. Name two mammals that lay eggs.
  7. Name the phylum of an animals with having water canal system.
  8. Name the female reproductive organ of plants.
  9. What is the meaning of Diploblastic?
  10. What do you mean by radial symmetry in animals?

Short Answer Questions (2 Marks)

  1. Give the characteristics of Protista.
  2. Give the difference between gymnosperms and angiosperms.
  3. What are the rules followed in binomial nomenclature?
  4. State the difference in non-chordates and chordates?
  5. What are the specific characteristics of coelenterata?

Short Answer Questions (3 Marks)

  1. What do you mean by dual life in plants and animals?
  2. Differentiate between Algae and fungi.
  3. What is the primary characteristic on which the first division of organisms is made?
  4. Which group – Pisces or Amphibia is advanced? Give two reasons.
  5. A, B and C are three plants. A bears seeds but no fruits, B bears sporangia arranged in sori and the plant body of C is gametophyte and has no vascular tissue. Identify the groups to which these plants belongs.

Long Answer Questions (5 marks)

  1. What is the importance of classification and why is it necessary?
  2. Give the hierarchy of five kingdom classification of living world.
  3. Give the outline classification of animal kingdom, with examples.
  4. Give the outline classification of plant kingdom, with examples.
  5. Give the characteristics of flatworms, roundworms and segmented worm. Give their phylum.

Value based questions

  1. Amit went to a place in Himachal Pradesh to spent vacations. This place was very rich in vegetation and while walking he touched a plant which caused irritation in his body. Native people told him that it is due to a plant known as Bicchu Butti. He got confused because a plant with similar name in Haryana is a beautiful soft ornamental plant.

(i)                    Why such confusion occurs about the identity of living organisms?

(ii)                   How such problem of identity can be solved and confusion and be avoided?

  1. While walking along roadside, Sunil asked his father, a biology teacher, whether some small, green, non-flowering, leafy and thalloid plants, having little differentiation of body and growing along pavement are of any use to us. Father answered that the plants are small but they play very important role in maintaining green covers on the land

(i)          To which group these small thalloid, green, non-flowering plants belong?

(ii)                   In what way bryophytes are useful to us?

(iii)        Which other groups of plants acts as colonizers of barren rocks and make land suitable for growth of higher plants? Do these plants play some role in pollution monitoring?

OBJECTIVE TYPE QUESTIONS :-

  1. The umbrella like spherical part of a button mushroom is

(a)     Pileus                                         (b)   Stipe

(c)     Sporangium                                (d)   Rhizomorph

  1. You are identifying a plant that possesses seeds but not fruits. It may belong to

(a)     Pteridophyta                                (b)   Gymnosperms

(c)     Bryophyta                                   (d)   Angiosperm

  1. Which of the following is not an aquatic adaptation

(a)     Skin is covered with scales/plates      (b) Gaseous exchange through gils

(c)     Presence of muscular tail            (d)   All the above characters

  1. Which of the following belongs to phylum annelids.

(a)     Earthworm                                  (b)   Leech

(c)     Both (a) and (b)                           (d)   Ascaris

  1. A specimen of a fish was given to students to identify the externally visible chordate features in it. Students would look for

(a)     Operculum                                  (b)   Notochord

(c)     Dorsal tubular nerve cord            (d)   Post anal tail

  1. Sepals of a typical flowers are

(a)     outermost whorl of floral leaves   (b)   innermost whorl of floral leaves

(c)     male reproductive organs             (d)   female reproductive organs

  1. Cells of spirogyra possess

(a)     Spindle-shaped chloroplasts        (b)   Collar-shaped chloroplasts

(c)     Pyrenoids                                    (d)   Star-shaped chloroplasts

  1. Mark the odd one out

(a)     Rohu                                           (b)   Sea horse

(c)     Jelly fish                                     (d)   Flying Fish

 

MCQ (DIVERSITY)

  1. Redwood tree of California reaches a height of

(a) 25 m                                    (b) 50 m

(c)                                            75 m (d) 100 m

  1. Homo : generic name : : sapines : ………….

(a) species name                       (b) human name

(c) division name                      (d) organisms name

  1. The basic unit of classification is

(a) variety                                 (b) genera

(c) family                                  (d) class

  1. Which of the following groups of plants is called vascular cryptogames?

(a) Thallophyta                          (b) Bryophyta

(c) Pteridophyta                        (d) Angiosperms

  1. Phylum Mollusca can be distinguished from other non-chordates by the presence of

(a) Bacterial symmetry and exoskeleton

(b) A mantle and gills

(c) Shell & non-segmented body

(d) Mantle and non-segmented body

  1. The phylum of sedentary animals is

(a) Mollusca                              (b) Echinodermata

(c) Porifera                                (d) Both (a) and (b)

  1. Choanocytes are unique to

(a) Protozoa                               (b) Porifera

(c) Mollusca                              (d) Echinodermata

  1. Tapeworm is member of phylum

(a) Mollusca                              (b) Porifera

(c) Nemaoda                              (d) Platyhelminthes

  1. True coelom appeared for the first time

(a) Mollusca                              (b) Nematoda

(c) Annelida                              (d) Arthropoda

  1. In the Pila, the gastropod mollusk, the organ of the locomotion is

(a) Mantle                                 (b) Foot

(c) Tentacles                             (d) Legs

 

 

WORKSHEET – 1

 

  1. Why do we classifying organisms?
  2. Give three examples of range of variations that you see in life forms around you.
  3. Which do you think is a more basic characteristic for classifying organisms?

          (i)       the place where they live

(ii)      the kind of cells they are made of why?

  1. What is the primary characteristic of first division of organisms is made?
  2. On what basis are plants and animals puts into difference categories?
  3. Who gave the five kingdom classification?
  4. Which organisms are called primitive and how are they different from the so called advanced organisms?
  5. Draw the hierarchy of classification.
  6. Draw the labelled diagram of two prokaryotic organisms and write two difference between them?
  7. Name the two characteristic of fungi.
  8. Draw a labelled diagram of Euglena.
  9. In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?
  10. Name the two fungal species with diagram.
  11. Explain the phylum plantae upto sub-divisions and example?
  12. Write three characteristics of Bryophytes?
  13. Bryophytes are known as amphibians plant. Why?
  14. Which is not an algae

(a) Ulva                                              (b) Urothrix

(c) Spirogyra                                       (d) Chara

  1. The nostoc belongs to phylum

(a) Protista                                         (b) Fungic

(c) Monera                                          (d) Plantae

  1. Pick out the wrong statement about plantae

(a) Autotrophic in nature                    (b) Multicellular eukaryotes

(c) Saprophytic in nature                    (d) All of the above’

  1. Which is not found in euglena

(a) Chloroplast                                    (b) Cell-wall

(c) Pellick                                           (d) Flagella

  1. Who wrote the book origin of species?

(a) R.H. Whittaker                              (b) Robert Hook

(c) Robert Brown                                (d) Charles Darwin

 

 

WORKSHEET – 2

 

  1. Define kingdom Animalia.
  2. Write a specific character of phylum porifera.
  3. Give one example of phylum platyhelminhes.
  4. Scoliodion belongs to which class of kingdom animalia.
  5. How many classes of kingdom Animalia consists warm blooded Animalia?
  6. What is protochordata? Give two examples Protochordata.
  7. Write two characters of starfish.
  8. Which is the largest phylum of animal kingdom. Give two examples of this phylum.
  9. Write two characteristic features of phylum Nematoda.
  10. Write two amphibians characters with example.
  11. Write short notes on

          (i)       cold blooded animals       (ii)      warm blooded animals

(iii)     notochord                        (iv)     triploblastic

  1. What is symmetry? How many different kinds of symmetry?
  2. What is acoelamate, pseudocoelemate and eucoelomate?
  3. Draw a labelled diagram of hydra and discuss about it.
  4. Write a short notes on Carolous Linnaeus.
  5. Explain the five different classes of chordata.
  6. Which one is a pseudocoelomate animal?

(a) Amoeba                                         (b) Hydra

(c) Earthworm                                    (d) Cockroach

  1. Which one is a four chambered animal?

(a) Pigeon                                           (b) Ostrich

(c) Crocodile                                       (d) All

  1. Starfish belongs to the phylum

(a) Annelida                                        (b) Mollusca

(c) Arthropoda                                    (d) Echinodermata

  1. Which one is triploblastic acoelomate?

(a) Hydra                                            (b) Cockroach

(c) Flatworms                                     (d) Earthworms

  1. Which one is not a cold-blooded animals?

(a) Pisces                                            (b) Amphibians

(c) Reptiles                                         (d) Aves

         

 

 

 

WORKSHEET – 3

 

  1. Define following terms :

(i)       Identification                            (ii)      Nomenclature        (iii)     Classification

  1. Write two examples of phylum protozoa.
  2. Write two characters of phylum coelenterata.
  3. Draw a labelled diagram of hydra.
  4. Define following terms :

          (i)       Asymmetry                      (ii)      Bilateral symmetry

(iii)     Radial symmetry             (iv)     Diploblastic (iv)     Triploblastic

  1. How many classes in phylum chordata?
  2. Which one is poikilothermic animal?

          (a)      Pisces                             (b)      Amphibians

(c)      Reptiles                          (d)      All

  1. Which are warm blooded animal

          (a)      Pisces                             (b)      Aves

(c)      Mammals                        (d)      Both (b) and (c)

  1. Which one does not belongs to phylum Arthropoda

          (a)      Earthworm                      (b)      Cockroach

(c)      Head lice                         (d)      termite

  1. Which is not a character of phylum annelida

          (a)      Metamerically segmented body

(b)      Closed vascular system

(c)      Paired appendages

(d)      Respiration by skin

 

 

 

         

 

WORKSHEET – 4

 

SET-A

  1. Where are the major difference between liverwort and harmwort.
  2. Name the cytoplasmic extensious used by Amoeba for locomotion.
  3. What are hermaphrodites? Name two such organisms.
  4. What is taxonomy? How is it useful?
  5. What are the salient feature of bacteria?

SET-B

  1. Thallophyta has undifferentiated body called thallus. Which other plants have an undifferentiated bodys.
  2. What is binomial system of nomenclature?
  3. Name the body cavities of the following and mention which animals have complete gut.
  4. What are the major differences between dicotyledons and monocotyledons?
  5. How do algae ‘differ from fungi’?

SET-C

  1. What are parapodia, setae and chaetae?
  2. The body of a mollusk is divided into 3 parts. Name these parts.
  3. Compare the character of Bryophyta and compare it with pteridophyta.
  4. Mention the characteristics of Hemichordata?
  5. What is coelom? How many different kinds of coelom.

SET-D

  1. Which organisms are included in the kingdom monera and which in the kingdom Protista?
  2. Which phylum do organisms of the genes plasmodium belongs to? Which disease is caused by them?
  3. How do molluscs breathe?
  4. What does diploblastic mean? Name an organisms which is diploblastic.
  5. What are the characteristics features of mammals?

 

 

 

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