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NEET Biology: Diversity in the Living World · Chapter 4

Animal Kingdom

What to remember

  • Animals are classified by level of organisation, symmetry, germ layers (diploblastic or triploblastic), coelom (acoelomate, pseudocoelomate, coelomate), segmentation and the notochord.
  • Non-chordate phyla in order of body plan: Porifera (cellular level), Coelenterata and Ctenophora (tissue level, diploblastic), Platyhelminthes (organ level, acoelomate), Aschelminthes (pseudocoelomate), then Annelida, Arthropoda, Mollusca, Echinodermata and Hemichordata (organ-system level, coelomate).
  • Chordates have a notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits. Subphyla: Urochordata, Cephalochordata, Vertebrata. Vertebrates have a vertebral column that replaces the notochord.
  • Heart chambers: fishes 2, amphibians 3, most reptiles 3 (crocodiles 4), birds 4, mammals 4. Birds and mammals are warm-blooded. Fishes, amphibians and reptiles are cold-blooded.

Basis of classification

BasisTypes and examples
Levels of organisationCellular (sponges); tissue (coelenterates, ctenophores); organ (flatworms); organ-system (annelids and higher phyla)
SymmetryAsymmetrical (most sponges); radial (coelenterates, ctenophores, adult echinoderms); bilateral (annelids, arthropods and others)
Germ layersDiploblastic: ectoderm and endoderm, with undifferentiated mesoglea between them (coelenterates, ctenophores). Triploblastic: ectoderm, mesoderm and endoderm (flatworms to chordates)
CoelomAcoelomate: no body cavity (flatworms). Pseudocoelomate: cavity not fully lined by mesoderm, as mesoderm is present as scattered pouches (roundworms). Coelomate: cavity lined by mesoderm (annelids, arthropods, molluscs, echinoderms, hemichordates, chordates)
SegmentationBody divided into repeated segments, called metamerism (annelids, arthropods, chordates)
NotochordA mesoderm-derived rod on the dorsal side. Present in chordates; absent in non-chordates

Non-chordates: Porifera, Coelenterata and Ctenophora

Porifera (sponges)

  • Mostly marine, asymmetrical, cellular level of organisation.
  • Water enters through many pores (ostia) into a central cavity (spongocoel) and leaves through the osculum. This is the canal system. Choanocytes (collar cells) line the spongocoel and canals.
  • Digestion is intracellular. The skeleton is of spicules or spongin fibres.
  • Sponges are hermaphrodite (bisexual). Asexual reproduction is by fragmentation. Fertilisation is internal. Development is indirect, with a larva unlike the adult.
  • Examples: Sycon, Spongilla (freshwater sponge), Euspongia (bath sponge).

Coelenterata (Cnidaria)

  • Aquatic, mostly marine, sessile or free-swimming, radially symmetrical, diploblastic, tissue level.
  • Cnidoblasts (cnidocytes) bear stinging capsules called nematocysts. They are used for anchorage, defence and capture of prey.
  • A central gastro-vascular cavity opens by a single opening, the hypostome.
  • Two body forms: polyp (sessile, cylindrical; Hydra, Adamsia) and medusa (umbrella-shaped, free-swimming; Aurelia). Obelia has both; polyps produce medusae asexually and medusae form polyps sexually.
  • Corals have a calcium carbonate skeleton.
  • Examples: Physalia (Portuguese man-of-war), Adamsia (sea anemone), Pennatula (sea pen), Gorgonia (sea fan), Meandrina (brain coral).

Ctenophora

  • Sea walnuts or comb jellies. Exclusively marine, radially symmetrical, diploblastic, tissue level.
  • Eight external rows of ciliated comb plates help in locomotion.
  • Digestion is both extracellular and intracellular. Bioluminescence is well marked.
  • Sexes are not separate. Only sexual reproduction occurs. Fertilisation is external. Development is indirect.
  • Examples: Pleurobrachia, Ctenoplana.

Non-chordates: Platyhelminthes to Hemichordata

PhylumKey featuresExamples
Platyhelminthes (flatworms)Dorsoventrally flattened; bilateral, triploblastic, acoelomate, organ level; mostly endoparasites with hooks and suckers; flame cells for osmoregulation and excretion; sexes not separate; internal fertilisation; high regeneration (Planaria)Taenia (tapeworm), Fasciola (liver fluke)
Aschelminthes (roundworms)Body circular in cross-section; bilateral, triploblastic, pseudocoelomate, organ-system level; complete alimentary canal with muscular pharynx; sexes separate, females often longer than males; development direct or indirectAscaris, Wuchereria (filaria worm), Ancylostoma (hookworm)
AnnelidaBilateral, triploblastic, coelomate, metamerically segmented; segments marked by transverse grooves; longitudinal and circular muscles; nephridia for excretion and osmoregulation; double ventral nerve cord; Nereis has parapodia for swimmingNereis (dioecious), Pheretima (earthworm), Hirudinaria (leech); earthworms and leeches are monoecious
ArthropodaLargest phylum; bilateral, triploblastic, segmented, coelomate; chitinous exoskeleton; body of head, thorax, abdomen; jointed appendages; gills, book gills, book lungs or trachea for respiration; open circulation; Malpighian tubules excrete; mostly dioecious, oviparousApis (honey bee), Bombyx (silkworm), Laccifer (lac insect), Anopheles, Culex, Aedes (vectors), Locusta (locust), Limulus (king crab, a living fossil)
MolluscaSecond largest phylum; bilateral, triploblastic, coelomate; soft body with head, muscular foot and visceral hump; calcareous shell; mantle covers the hump and the mantle cavity holds feather-like gills; radula (file-like rasping organ) in the mouth; usually dioecious, oviparous, indirect developmentPila (apple snail), Pinctada (pearl oyster), Sepia (cuttlefish), Loligo (squid), Octopus (devil fish), Aplysia, Dentalium, Chaetopleura
EchinodermataSpiny skin from calcareous ossicles; all marine; adults radially symmetrical but larvae bilateral; triploblastic, coelomate; water vascular system for locomotion, food capture and respiration; excretory system absent; sexes separate; external fertilisation; indirect developmentAsterias (star fish), Echinus (sea urchin), Antedon (sea lily), Cucumaria (sea cucumber), Ophiura (brittle star)
HemichordataWorm-like marine animals; body of proboscis, collar and long trunk; bilateral, triploblastic, coelomate; open circulation; respiration by gills; proboscis gland excretes; sexes separate; external fertilisation; indirect developmentBalanoglossus, Saccoglossus

Hemichordates were earlier placed in Chordata. They are now treated as a separate non-chordate phylum.

Chordata

All chordates have these three features at some stage of life:

  • A notochord.
  • A dorsal, hollow, single nerve cord.
  • Paired pharyngeal gill slits.

Chordates are bilaterally symmetrical, triploblastic, coelomate and at organ-system level. They also have a post-anal tail and a closed circulatory system.

FeatureNon-chordatesChordates
NotochordAbsentPresent
Central nervous systemVentral, solid and doubleDorsal, hollow and single
PharynxWithout gill slitsPaired gill slits present (at least in the embryo)
HeartDorsal, if presentVentral
Post-anal tailAbsentPresent

Subphyla:

  • Urochordata (tunicates): notochord is present only in the larval tail. Examples: Ascidia, Salpa, Doliolum.
  • Cephalochordata: notochord extends from head to tail and stays for life. Example: Branchiostoma (Amphioxus, lancelet).
  • Vertebrata: the notochord is present in the embryo and is replaced by a cartilaginous or bony vertebral column in the adult. The heart is ventral and muscular with 2, 3 or 4 chambers. Kidneys excrete and osmoregulate. Paired appendages (fins or limbs) are present.

Classes of vertebrates

Cyclostomata: all are ectoparasites on fishes. The body is elongated with 6–15 pairs of gill slits. The mouth is circular and sucking, without jaws. Cranium and vertebral column are cartilaginous. They have no limbs and no scales. They live in the sea but migrate to fresh water to spawn. Larvae return to the ocean after metamorphosis. Examples: Petromyzon (lamprey), Myxine (hagfish).

Chondrichthyes: marine, streamlined, with a cartilaginous endoskeleton. The mouth is ventral. The notochord persists through life. Gill slits are separate and have no operculum. The skin has placoid scales. Teeth are modified placoid scales. There is no air bladder, so the fish must keep swimming to avoid sinking. The heart is two-chambered. They are cold-blooded. Males have claspers on the pelvic fins. Fertilisation is internal and most are viviparous. Examples: Scoliodon (dog fish), Pristis (saw fish), Carcharodon (great white shark), Trygon (sting ray), Torpedo (electric ray).

Osteichthyes: marine and fresh water, with a bony endoskeleton. The mouth is mostly terminal. Four pairs of gills are covered by an operculum. The skin has cycloid or ctenoid scales. An air bladder regulates buoyancy. The heart is two-chambered. They are cold-blooded. Fertilisation is usually external. Most are oviparous with direct development. Examples: Exocoetus (flying fish), Hippocampus (sea horse), Labeo (rohu), Catla, Clarias (magur), Betta (fighting fish), Pterophyllum (angel fish).

Amphibia: live in water and on land. There are two pairs of limbs. The skin is moist and without scales. The eyes have eyelids. The tympanum represents the ear. The alimentary canal, urinary and reproductive tracts open into a common cloaca. Respiration is by gills, lungs and skin. The heart is three-chambered. They are cold-blooded. Fertilisation is external. They are oviparous with direct or indirect development. Examples: Bufo (toad), Rana (frog), Hyla (tree frog), Salamandra, Ichthyophis (limbless).

Reptilia: creeping or crawling animals. The skin is dry and cornified, with epidermal scales or scutes. The tympanum represents the ear. The heart is usually three-chambered but four-chambered in crocodiles. They are cold-blooded. Snakes and lizards shed their scales as skin cast. Fertilisation is internal. They are oviparous with direct development. Examples: Chelone (turtle), Testudo (tortoise), Calotes (garden lizard), Hemidactylus (wall lizard), Crocodilus, Alligator, Naja (cobra), Bangarus (krait), Vipera (viper).

Aves: the body has feathers. Forelimbs are modified into wings. Most fly, but some such as the ostrich are flightless. Hind limbs have scales. The skin is dry, with only an oil gland at the base of the tail. Long bones are hollow with air cavities (pneumatic bones). The digestive tract has a crop and a gizzard. The heart is four-chambered. They are warm-blooded. Respiration is by lungs, aided by air sacs. Fertilisation is internal. They are oviparous with direct development. Examples: Corvus (crow), Columba (pigeon), Psittacula (parrot), Struthio (ostrich), Pavo (peacock), Aptenodytes (penguin), Neophron (vulture).

Mammalia: found in all kinds of habitats, and some fly or live in water. The defining feature is mammary glands that feed the young. The skin has hair. External ears (pinnae) are present. The teeth are of different types (heterodont) and are set in sockets. The heart is four-chambered. They are warm-blooded. Fertilisation is internal. Most are viviparous with direct development. Examples: Ornithorhynchus (platypus, oviparous), Macropus (kangaroo), Pteropus (flying fox), Camelus (camel), Macaca (monkey), Rattus (rat), Canis (dog), Felis (cat), Elephas (elephant), Equus (horse), Delphinus (dolphin), Balaenoptera (blue whale), Panthera tigris (tiger), Panthera leo (lion).

ClassSkin or coverHeart chambersBody temperatureFertilisation
CyclostomataSmooth, no scales2Cold-bloodedExternal
ChondrichthyesPlacoid scales2Cold-bloodedInternal
OsteichthyesCycloid or ctenoid scales2Cold-bloodedUsually external
AmphibiaMoist, no scales3Cold-bloodedExternal
ReptiliaDry, scales or scutes3 (4 in crocodiles)Cold-bloodedInternal
AvesFeathers4Warm-bloodedInternal
MammaliaHair4Warm-bloodedInternal

Quick comparison of phyla

PhylumSymmetryGerm layersBody cavitySpecial structure
PoriferaAsymmetrical (mostly)No true layersNot applicableChoanocytes, spicules
CoelenterataRadialDiploblasticGastro-vascular cavityNematocysts
CtenophoraRadialDiploblasticPresent as gastro-vascular systemComb plates
PlatyhelminthesBilateralTriploblasticAcoelomateFlame cells
AschelminthesBilateralTriploblasticPseudocoelomateMuscular pharynx
AnnelidaBilateralTriploblasticCoelomateMetameric segments, nephridia
ArthropodaBilateralTriploblasticCoelomateJointed appendages
MolluscaBilateralTriploblasticCoelomateRadula, mantle
EchinodermataRadial in adultsTriploblasticCoelomateWater vascular system
HemichordataBilateralTriploblasticCoelomateProboscis, collar, trunk

Remember the order of heart evolution in vertebrates. Fishes have a two-chambered heart with one auricle and one ventricle. Amphibians have two auricles and one ventricle. Birds and mammals have two auricles and two ventricles, so oxygenated and deoxygenated blood do not mix.

NEET traps

  • 1. Coelenterates and ctenophores are diploblastic. Flatworms and above are triploblastic.
  • 2. Flatworms are acoelomate. Roundworms are pseudocoelomate. Annelids are coelomate.
  • 3. Flatworms use flame cells. Annelids use nephridia. Arthropods use Malpighian tubules.
  • 4. Arthropods are the largest phylum. Molluscs are the second largest.
  • 5. Adult echinoderms are radially symmetrical but their larvae are bilateral.
  • 6. Hemichordates are not chordates. They have no true notochord and are placed among non-chordates.
  • 7. In Urochordata the notochord is only in the larval tail. In Cephalochordata it runs from head to tail for life.
  • 8. Chondrichthyes have no air bladder and no operculum. Osteichthyes have both.
  • 9. Fertilisation is internal in Chondrichthyes but usually external in Osteichthyes.
  • 10. Crocodiles are reptiles with a four-chambered heart. Other reptiles generally have three chambers.

One-liners

  • 1. Porifera have cellular organisation, choanocytes and an osculum.
  • 2. Nematocysts are stinging capsules of cnidarians.
  • 3. Ctenophores move by eight rows of ciliated comb plates.
  • 4. Flame cells are found in flatworms.
  • 5. Roundworms have separate sexes and a complete alimentary canal.
  • 6. Parapodia of Nereis help swimming.
  • 7. Arthropods have a chitinous exoskeleton and jointed appendages.
  • 8. Molluscs have a radula, mantle and calcareous shell.
  • 9. Echinoderms have a water vascular system.
  • 10. Balanoglossus has a proboscis, collar and trunk.
  • 11. Chordates have a notochord, dorsal hollow nerve cord and pharyngeal gill slits.
  • 12. Branchiostoma is a cephalochordate.
  • 13. Cyclostomes lack jaws and paired fins.
  • 14. Male sharks have claspers.
  • 15. Birds have pneumatic bones, a crop and a gizzard.

Practice questions

  1. Which phylum shows only the cellular level of organisation?

    1. Annelida
    2. Platyhelminthes
    3. Coelenterata
    4. Porifera
    Answer

    D. Porifera

    Sponges have cells loosely arranged without true tissues.

  2. Which phylum is acoelomate?

    1. Annelida
    2. Platyhelminthes
    3. Aschelminthes
    4. Mollusca
    Answer

    B. Platyhelminthes

    Flatworms have no body cavity; roundworms are pseudocoelomate.

  3. Cnidoblasts bearing nematocysts are characteristic of

    1. Ctenophora
    2. Echinodermata
    3. Coelenterata
    4. Porifera
    Answer

    C. Coelenterata

    Cnidoblasts are stinging cells used for defence and prey capture.

  4. Eight rows of ciliated comb plates are found in

    1. Ctenophora
    2. Coelenterata
    3. Hemichordata
    4. Porifera
    Answer

    A. Ctenophora

    Comb jellies move using comb plates.

  5. Malpighian tubules are the excretory organs of

    1. Arthropoda
    2. Platyhelminthes
    3. Annelida
    4. Mollusca
    Answer

    A. Arthropoda

    Arthropods excrete through Malpighian tubules.

  6. The file-like rasping organ in the mouth of a snail is the

    1. spongin
    2. operculum
    3. radula
    4. proboscis
    Answer

    C. radula

    Molluscs feed with a radula.

  7. The water vascular system helps in locomotion, food capture and respiration in

    1. Arthropoda
    2. Annelida
    3. Mollusca
    4. Echinodermata
    Answer

    D. Echinodermata

    This system is a feature of echinoderms such as Asterias.

  8. Which animal has a body made of proboscis, collar and trunk?

    1. Asterias
    2. Balanoglossus
    3. Ascidia
    4. Branchiostoma
    Answer

    B. Balanoglossus

    Balanoglossus is a hemichordate.

  9. In which group is the notochord present only in the larval tail?

    1. Cephalochordata
    2. Vertebrata
    3. Urochordata
    4. Cyclostomata
    Answer

    C. Urochordata

    Tunicates lose the notochord in the adult.

  10. Branchiostoma is placed in the subphylum

    1. Cephalochordata
    2. Urochordata
    3. Vertebrata
    4. Hemichordata
    Answer

    A. Cephalochordata

    Its notochord runs from head to tail and persists.

  11. Which of the following is a cyclostome?

    1. Pristis
    2. Petromyzon
    3. Labeo
    4. Torpedo
    Answer

    B. Petromyzon

    Petromyzon (lamprey) has a circular, jawless sucking mouth.

  12. Which feature is true of Chondrichthyes?

    1. Three-chambered heart
    2. Operculum covering the gills
    3. Bony endoskeleton
    4. No air bladder
    Answer

    D. No air bladder

    Cartilaginous fishes lack an air bladder and an operculum.

  13. Which of the following is a bony fish?

    1. Hippocampus
    2. Pristis
    3. Trygon
    4. Scoliodon
    Answer

    A. Hippocampus

    Hippocampus (sea horse) belongs to Osteichthyes.

  14. The amphibian heart has

    1. one auricle and two ventricles
    2. two auricles and one ventricle
    3. two auricles and two ventricles
    4. one auricle and one ventricle
    Answer

    B. two auricles and one ventricle

    Amphibians have a three-chambered heart.

  15. Which of the following is a flightless bird?

    1. Columba
    2. Corvus
    3. Struthio
    4. Psittacula
    Answer

    C. Struthio

    Struthio is the ostrich.

  16. Which of the following is an egg-laying mammal?

    1. Delphinus
    2. Pteropus
    3. Macropus
    4. Ornithorhynchus
    Answer

    D. Ornithorhynchus

    The platypus is oviparous; the others are viviparous.

  17. Given below are two statements: Statement I: Coelenterates are diploblastic. Statement II: Flatworms are pseudocoelomate.

    1. Statement I is correct but Statement II is incorrect
    2. Both Statement I and Statement II are correct
    3. Both Statement I and Statement II are incorrect
    4. Statement I is incorrect but Statement II is correct
    Answer

    A. Statement I is correct but Statement II is incorrect

    Flatworms are acoelomate.

  18. Given below are two statements: Statement I: Annelids are metamerically segmented. Statement II: Aschelminthes have separate sexes.

    1. Both Statement I and Statement II are incorrect
    2. Statement I is correct but Statement II is incorrect
    3. Statement I is incorrect but Statement II is correct
    4. Both Statement I and Statement II are correct
    Answer

    D. Both Statement I and Statement II are correct

    Both are correct.

  19. Given below are two statements: Statement I: Molluscs form the largest phylum of animals. Statement II: Arthropods have an open circulatory system.

    1. Both Statement I and Statement II are correct
    2. Both Statement I and Statement II are incorrect
    3. Statement I is incorrect but Statement II is correct
    4. Statement I is correct but Statement II is incorrect
    Answer

    C. Statement I is incorrect but Statement II is correct

    Arthropoda is the largest phylum; molluscs are second.

  20. Which of the following statements are correct? 1. Adult echinoderms are radially symmetrical. 2. Echinoderm larvae are radially symmetrical. 3. Echinoderms have no excretory system.

    1. 1 and 2 only
    2. 1 and 3 only
    3. 2 and 3 only
    4. 1, 2 and 3
    Answer

    B. 1 and 3 only

    Echinoderm larvae are bilaterally symmetrical.

  21. Given below are two statements: Statement I: Hemichordata is a subphylum of Chordata. Statement II: The body of a hemichordate has a proboscis, collar and trunk.

    1. Both Statement I and Statement II are correct
    2. Statement I is incorrect but Statement II is correct
    3. Both Statement I and Statement II are incorrect
    4. Statement I is correct but Statement II is incorrect
    Answer

    B. Statement I is incorrect but Statement II is correct

    Hemichordates are a separate non-chordate phylum.

  22. Given below are two statements: Statement I: Chondrichthyes have a two-chambered heart. Statement II: Osteichthyes lack an operculum.

    1. Statement I is correct but Statement II is incorrect
    2. Both Statement I and Statement II are correct
    3. Both Statement I and Statement II are incorrect
    4. Statement I is incorrect but Statement II is correct
    Answer

    A. Statement I is correct but Statement II is incorrect

    Bony fishes have an operculum covering the gills.

  23. Which of the following statements are correct? 1. Reptiles have a three-chambered heart, except crocodiles. 2. Reptiles have moist skin without scales. 3. Fertilisation in reptiles is internal.

    1. 1 and 2 only
    2. 2 and 3 only
    3. 1, 2 and 3
    4. 1 and 3 only
    Answer

    D. 1 and 3 only

    Reptile skin is dry and cornified.

  24. Given below are two statements: Statement I: Birds are warm-blooded. Statement II: Amphibians have a common cloaca for the digestive, urinary and reproductive tracts.

    1. Both Statement I and Statement II are incorrect
    2. Statement I is correct but Statement II is incorrect
    3. Both Statement I and Statement II are correct
    4. Statement I is incorrect but Statement II is correct
    Answer

    C. Both Statement I and Statement II are correct

    Both are correct.

  25. Which of the following statements are correct? 1. Cyclostomes are ectoparasites on fishes. 2. Cyclostomes have a sucking, circular mouth with jaws. 3. Cyclostomes have 6 to 15 pairs of gill slits.

    1. 1 and 2 only
    2. 2 and 3 only
    3. 1 and 3 only
    4. 1, 2 and 3
    Answer

    C. 1 and 3 only

    Cyclostomes are jawless.

  26. Given below are two statements: Statement I: In Cephalochordata the notochord extends from head to tail and persists through life. Statement II: In Urochordata the notochord is present throughout the adult body.

    1. Both Statement I and Statement II are correct
    2. Statement I is correct but Statement II is incorrect
    3. Both Statement I and Statement II are incorrect
    4. Statement I is incorrect but Statement II is correct
    Answer

    B. Statement I is correct but Statement II is incorrect

    In Urochordata the notochord is limited to the larval tail.

  27. Assertion (A): Sharks must swim constantly to avoid sinking. Reason (R): Chondrichthyes lack an air bladder.

    1. Both A and R are true and R is the correct explanation of A
    2. Both A and R are true but R is not the correct explanation of A
    3. A is true but R is false
    4. A is false but R is true
    Answer

    A. Both A and R are true and R is the correct explanation of A

    No air bladder means no buoyancy control.

  28. Assertion (A): Coelenterates use cnidoblasts for defence and prey capture. Reason (R): Cnidoblasts contain stinging capsules called nematocysts.

    1. Both A and R are true but R is not the correct explanation of A
    2. A is true but R is false
    3. A is false but R is true
    4. Both A and R are true and R is the correct explanation of A
    Answer

    D. Both A and R are true and R is the correct explanation of A

    Nematocysts deliver the sting.

  29. Assertion (A): Amphibians are cold-blooded animals. Reason (R): Reptiles have a dry, cornified skin.

    1. Both A and R are true and R is the correct explanation of A
    2. A is true but R is false
    3. A is false but R is true
    4. Both A and R are true but R is not the correct explanation of A
    Answer

    D. Both A and R are true but R is not the correct explanation of A

    Both are true but the skin type does not explain body temperature.

  30. Assertion (A): Ctenophores show bioluminescence. Reason (R): Ctenophores are freshwater animals.

    1. Both A and R are true and R is the correct explanation of A
    2. Both A and R are true but R is not the correct explanation of A
    3. A is true but R is false
    4. A is false but R is true
    Answer

    C. A is true but R is false

    Ctenophores are exclusively marine.

  31. Assertion (A): Adult echinoderms are bilaterally symmetrical. Reason (R): Echinoderm larvae are bilaterally symmetrical.

    1. Both A and R are true and R is the correct explanation of A
    2. A is false but R is true
    3. Both A and R are true but R is not the correct explanation of A
    4. A is true but R is false
    Answer

    B. A is false but R is true

    Adults are radially symmetrical; larvae are bilateral.

  32. Assertion (A): Parasitic flatworms have hooks and suckers. Reason (R): Hooks and suckers help them attach to the host.

    1. Both A and R are true and R is the correct explanation of A
    2. Both A and R are true but R is not the correct explanation of A
    3. A is true but R is false
    4. A is false but R is true
    Answer

    A. Both A and R are true and R is the correct explanation of A

    These structures give attachment.

  33. Match List I with List II. List I: a. Porifera b. Coelenterata c. Echinodermata d. Hemichordata List II: i. Balanoglossus ii. Spongilla iii. Pennatula iv. Asterias

    1. a-iii, b-ii, c-iv, d-i
    2. a-ii, b-iii, c-i, d-iv
    3. a-ii, b-iii, c-iv, d-i
    4. a-ii, b-iv, c-iii, d-i
    Answer

    C. a-ii, b-iii, c-iv, d-i

    Spongilla, Pennatula, Asterias and Balanoglossus respectively.

  34. Match List I with List II. List I: a. Annelida b. Arthropoda c. Mollusca d. Platyhelminthes List II: i. Radula ii. Flame cells iii. Nephridia iv. Malpighian tubules

    1. a-iii, b-iv, c-ii, d-i
    2. a-iv, b-iii, c-i, d-ii
    3. a-iii, b-i, c-iv, d-ii
    4. a-iii, b-iv, c-i, d-ii
    Answer

    D. a-iii, b-iv, c-i, d-ii

    Nephridia, Malpighian tubules, radula and flame cells respectively.

  35. Match List I with List II. List I: a. Cyclostomata b. Chondrichthyes c. Osteichthyes d. Amphibia List II: i. Rana ii. Labeo iii. Petromyzon iv. Trygon

    1. a-iii, b-iv, c-ii, d-i
    2. a-iv, b-iii, c-ii, d-i
    3. a-iii, b-ii, c-iv, d-i
    4. a-iii, b-iv, c-i, d-ii
    Answer

    A. a-iii, b-iv, c-ii, d-i

    Petromyzon, Trygon, Labeo and Rana respectively.

  36. Match List I with List II. List I: a. Struthio b. Naja c. Hyla d. Pteropus List II: i. Reptilia ii. Mammalia iii. Aves iv. Amphibia

    1. a-i, b-iii, c-iv, d-ii
    2. a-iii, b-i, c-iv, d-ii
    3. a-iii, b-iv, c-i, d-ii
    4. a-iii, b-i, c-ii, d-iv
    Answer

    B. a-iii, b-i, c-iv, d-ii

    Struthio is a bird, Naja a reptile, Hyla an amphibian and Pteropus a mammal.

  37. Match List I with List II. List I: a. Limulus b. Laccifer c. Loligo d. Hippocampus List II: i. Sea horse ii. Squid iii. King crab iv. Lac insect

    1. a-iii, b-ii, c-iv, d-i
    2. a-iii, b-iv, c-ii, d-i
    3. a-iii, b-iv, c-i, d-ii
    4. a-iv, b-iii, c-ii, d-i
    Answer

    B. a-iii, b-iv, c-ii, d-i

    King crab, lac insect, squid and sea horse respectively.

  38. Match List I with List II. List I: a. Osteichthyes b. Amphibia c. Aves d. Reptilia List II: i. Two auricles and one ventricle ii. Two chambers iii. Four chambers iv. Usually three chambers, four in crocodiles

    1. a-ii, b-i, c-iii, d-iv
    2. a-ii, b-iii, c-i, d-iv
    3. a-i, b-ii, c-iii, d-iv
    4. a-ii, b-i, c-iv, d-iii
    Answer

    A. a-ii, b-i, c-iii, d-iv

    Fishes have two chambers, amphibians three, birds four, reptiles usually three.

  39. A worm from a pig's intestine is round in cross-section, has separate sexes, a complete alimentary canal and a pseudocoelom. It belongs to

    1. Mollusca
    2. Annelida
    3. Aschelminthes
    4. Platyhelminthes
    Answer

    C. Aschelminthes

    These are features of roundworms.

  40. An aquatic animal has a soft unsegmented body, a muscular foot, a mantle cavity with gills, a radula and a calcareous shell. It belongs to

    1. Annelida
    2. Echinodermata
    3. Arthropoda
    4. Mollusca
    Answer

    D. Mollusca

    Foot, mantle, radula and shell are molluscan features.

  41. A free-swimming larva has a notochord in its tail, but the adult is sac-like and has lost it. The animal belongs to

    1. Cephalochordata
    2. Vertebrata
    3. Hemichordata
    4. Urochordata
    Answer

    D. Urochordata

    Notochord restricted to the larval tail is a urochordate feature.

  42. A marine fish has placoid scales, no operculum and claspers on the pelvic fins of the male. It is a member of

    1. Osteichthyes
    2. Chondrichthyes
    3. Amphibia
    4. Cyclostomata
    Answer

    B. Chondrichthyes

    Placoid scales, no operculum and claspers are chondrichthyan features.

  43. A vertebrate has moist scaleless skin, a three-chambered heart, a cloaca and external fertilisation. It is a

    1. frog (Rana)
    2. shark (Scoliodon)
    3. lizard (Calotes)
    4. pigeon (Columba)
    Answer

    A. frog (Rana)

    These are amphibian features.

  44. A chordate keeps its notochord from head to tail throughout life and has no vertebral column. It belongs to

    1. Cyclostomata
    2. Urochordata
    3. Cephalochordata
    4. Vertebrata
    Answer

    C. Cephalochordata

    Persistent head-to-tail notochord is typical of Branchiostoma.

  45. A swimmer is stung by a Portuguese man-of-war. The stinging structures involved are

    1. comb plates
    2. flame cells
    3. radulae
    4. nematocysts of cnidoblasts
    Answer

    D. nematocysts of cnidoblasts

    Cnidarians sting with nematocysts.

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