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(c) Platylelminthes

Correct Answer is: (a) Prawn

Correct Answer is: (a) Prawn

(b) respiration

Correct Answer is: (d) Prawns

(b) flame cells of Planaria

(b) Flame cells of Planaria

(d) both (a) and (b)

Correct Answer is: (c) Louse

(a) A – s, B – p, C – q, D – r

(d) various aspects of insects.

The exoskeleton of insect is made up of chitin.

(d) Complete metamorphosis

(b) ventral nerve cord

• The characteristics that contribute to the success of reptiles on land are as follows: 
• The presence of dry and comified skin with epidermal scales or scutes which prevent the loss of water. 
• The presence of metanephric kidney. 
• They are uricotelic (they excrete uric acid to prevent the loss of water).

Yes, it is also found in class Amphibia of phylum Chordata.

Metamorphosis is the process of developmental stages of an organism after birth or hatching. Ecdysone is a steroid hormone which is secreted from prothoracic glands of insects and controls ecdysis (metamorphosis). It is produced by prothoracic glands of insects and helps in molting. 

So, the correct answer is OPTION(B)

Hormone, which helps in metamorphosis in insects is ecdysone.

Correct Answer is: (a) Hirudin

(a) corpora allata

(a) Acarology

(d) Marine poisonous snakes

Correct Answer is: (d) python

Characteristic features of class Cyclostomata (Cyclos: Circular, stoma-mouth) Lat/Grk

1. Members of class Cyclostomata are jaw-less and eel like organisms.

2. Their skin is devoid of scales, soft and smooth, containing unicellular mucus glands. 

3. Median fms are present but paired fins are absent. 

4. They are ectoparasites on fishes. 

5. They have sucking circular mouth, without jaws.

6. Cranium and vertebral column are made up of cartilage. 

7. Their digestive system lacks stomach. 

8. Respiration occurs by 6 – 15 pairs of gill slits. Gills slits are without operculum. 

9. Heart is two chambered with one auricle and one ventricle. 

10. Gonad is single, large and without gonoduct. 

11. Fertilization is external. They are anadromous as they migrate for spawning to fresh – water from marine habitat. 

12. After spawning, they die within few days. Larvae metamorphosize and migrate to ocean.e.g Petromyzon (Lamprey), Myxine (Hagfish).

Animals like Ascaris show sexual dimorphism. The male Ascaris is shorter and narrower than the female and has a curved posterior end with a pair of penial setae for copulation. The female Ascaris is relatively longer and broader and has a straight posterior end without penial setae.

Nervous system: Brain is enlarged with a well developed cerebellum for equilibrium.

(d) cockroach

1. Cephalochordates are also known as lancelets and are small fish-like animals that rarely exceed 5 cm in length. 

2. Lancelets are exclusively marine and live partly buried in soft marine sediments. 

3. Notochord extends throughout entire length of the body and persists throughout life. 

4. Myotomes (muscle blocks) are present. 

5. Post anal tail is present. 

6. Circulatory system is closed type. Blood lacks pigment, e.g. Branchiostoma

The archenteron becomes the cavity of the digestive tract.

Ctenophores are exclusively marine. They emit light. It helps the animals in finding food, mate and escape from the predators.

Correct Answer is: (c) sponges

The members of this phylum are called as flatworms. 

Unique features of phylum Platyhelminthes: 

1. Body shape: Body of these animals is dorsoventrally flattened. 

2. Coelom: They are acoelomates. 

3. Germ layers: Platyhelminthes are triploblastic. 

4. Body organization: They show organ-system grade of organization. 

5. Forms: Most of them are endoparasites and few are free-living. Parasitic forms have hooks and suckers for attachment to the hosts’ body. In parasitic forms, body is covered by cuticle and in free-living forms it is covered by cilia. 

6. Digestive system: Parasitic forms generally lack digestive system. In free-living forms, the digestive system is incomplete. 

7. Body plan: They show blind-sac body plan. 

8. Excretion and osmoregulation: It occurs by flame cells or protonephridia. 

9. Reproduction: They are mostly hermaphrodite (bisexual). 

10. Self-fertilization: Few animals show high power of regeneration and show polyembryony. e.g. Planaria, Taenia (Tapeworm), Fasciola (Liver fluke) are included in this phylum.

Mollusca (Mollis: Soft) is the second-largest phylum. 

Unique features of phylum Mollusca:

1. Habitat: They are aquatic or seen in marshy places. Few of them are terrestrial. 

2. Forms: Molluscs are either free-living or sedentary. 

3. Body plan: These are soft bodied and show tube within a tube type of body plan. 

4. Body symmetry: Most of the Molluscs show bilateral symmetry but few are asymmetrical due to torsion (twisting). 

5. Body division: Body consists of head, foot and visceral mass. Visceral mass is enclosed in thick, muscular fold of body wall called mantle. Mantle secretes a hardcalcareous shell, that may be external or internal or absent. Muscular foot is present ventrally. 

6. Digestive system: Digestive system is well-developed and complete with anterior mouth and posterior anus. Buccal cavity has a rasping organ called radula (helps in feeding), which is provided with transverse rows of teeth. 

7. Respiration: In aquatic forms, numerous feather-like gills called ctenidia, help in aquatic respiration. Terrestrial forms may show the presence of lungs. 

8. Circulatory system: Circulatory system is of open type (except in Sepia, where it is of the closed type). Blood contains a copper-containing blue-coloured respiratory pigment called hemocyanin. 

9. Excretion: Excretion occurs by kidney-like structures, also called ‘Organ of Bojanus’. 

10. Nervous system and sense organs; Nervous system has three rjahs of Mf hxese, interconnected by commissures and connectives.

11. Sense organs: Sense organs such as eyes for vision, tentacles for tactile sensation and osphradia for testing purity of water is present. 

12. Sexual reproduction: Sexes are usually separate. Animals of this phylum are mostly oviparous and the development is direct or indirect. e.g. Pila, Spisula (Bivalve), Octopus (devil fish), Sepia (cuttle fish), Chaetopleura (Chiton), Pinctada (Pearl oyster), Loligo (Squid), Aplysia (Sea hare), Dentalium (Tusk shell).

Cydippid larva.

Exoskeleton: Body is covered by a tough, non – living chitinous exoskeleton. As the exoskeleton does not allow body growth, arthropods shed off their exoskeleton periodically during growth. This process is called moulting or ecdysis.

(a) Sea anemone (Adarnasia) 

(b) Radial symmetry 

(c) No 

(d) Two (ectoderm and endoderm) 

(e) One 

(f) No.

Acoelomates do not have body cavity. Their body is solid and hence the movement of internal organs is restricted. Pseudocoelomates have pseudocoelomic fluid in the pseudocoelom. It acts as a hydrostatic skeleton and allows free movement of visceral organs and circulation of nutrients.

The members of this phylum are commonly known as comb jellies and sea walnuts. They are also known as acnidarians as they lack cnidoblasts. The phylum is considered as one of the minor phyla as it is represented by very few members.  

Salient features of phylum Ctenophora: 

1. Habitat: They are exclusively marine. 

2. Forms: They are free swimming animals. 

3. Germ layers: Members of this phylum are diploblastic. 

4. Body Symmetry: They are radially symmetrical. 

5. Body plan: The animals of this phylum show blind-sac body plan.

6. Body organization: They show tissue level organization. 

7. Locomotion: It is earned out by eight rows of ciliated comb plates. 

8. Bioluminescence: It is the characteristic feature of the members of this phylum. 

9. Digestion: It is extracellular and intracellular. 

10. Reproduction: Reproduction is sexual with indirect development. 

11. Colloblasts: These sticky cells are used to capture prey, e.g. Pleurobrachia, Ctenoplan

The members of this phylum are called as flatworms. 

Unique features of phylum Platyhelminthes: 

1. Body shape: Body of these animals is dorsoventrally flattened. 

2. Coelom: They are acoelomates. 

3. Germ layers: Platyhelminthes are triploblastic. 

4. Body organization: They show organ-system grade of organization.

5. Forms: Most of them are endoparasites and few are free-living. Parasitic forms have hooks and suckers for attachment to the hosts’ body. In parasitic forms, body is covered by cuticle and in free-living forms it is covered by cilia. 

6. Digestive system: Parasitic forms generally lack digestive system. In free-living forms, the digestive system is incomplete. 

7. Body plan: They show blind-sac body plan. 

8. Excretion and osmoregulation: It occurs by flame cells or protonephridia. 

9. Reproduction: They are mostly hermaphrodite (bisexual). Self fertilization is seen. 

10. Few animals show high power of regeneration and show polyembryony. e.g. Planaria, Taenia (Tapeworm), Fasciola (Liver fluke) are included in this phylum.

Flame cells are the specialized excretory cells in flat worms. They help in excretion and osmoregulation.

Characteristics of members belonging to phylum Cnidaria: 

1. Habitat: They are aquatic, mostly marine and few of them are fresh – water forms. 

2. Forms: They are sessile or free swimming. 

3. Cnidoblasts: Presence of cnidoblasts or stinging cells are present on the tentacles for anchorage, offence and defence. 

4. Body Symmetry: They have radially symmetrical body.

5. Germ layer: They are diploblastic. 

6. Body cavity: Cnidarians have a central cavity called coelenteron or gastrovascular cavity, which helps in digestion and circulation. They have blind-sac body plan i.e., single pore opening to the exterior in the digestive system. 

7. Body form: Members of this phylum exhibit two body forms. The cylindrical form, known as polyp e.g. Hydra and the umbrella – like form (.Aurelia – jelly fish) is known as medusa. 

8. Digestion: They have extracellular and intracellular digestion. 

9. Reproduction: Cnidarians reproduce asexually and sexually.

Asexual reproduction takes place by budding and regeneration. Sexual reproduction takes place gamete formation. They exhibit metagenesis i.e. alternation of polypoid generation with medusoid generation. Polyps produce medusae asexually and medusae produce polyps sexually, e.g. Obelia e.g. Hydra, Aurelia (Jellyfish), Physalia (Portuguese man-ofwar), Adamsia (Sea anemone), Diploria (Brain coral), Gorgonia (sea fan).

The animals which do not possess a body cavity are called acoelomates. The body is solid without perivisceral cavity. These have restricted free movement of internal organs, e.g. Flatworms.

• Notochord, cephalisation, dorsal nerve cord and radial symmetry.
• Notochord, cephalisation and dorsal nerve cord are the characteristic features of chordates. The radial symmetry is not a characteristic feature of chordate. It is the feature of cnidarian and adult echinoderms. Hence it does not belong to the group.

Flat worms are called acoelomate because they do not possess a body cavity.

Annelids are commonly called as ring worms or segmented worms.

Characteristic feature of phylum Annelida: 

1. Forms: Annelids may be aquatic, ectoparasitic or free – living or burrowing in moist soil. 

2. Body symmetry: They are bilaterally symmetrical. 

3. Body coelom: They are true coelomates. 

4. Segmentation: Body is metamerically segmented and has a special region called clitellum. 

5. Digestive system: Alimentary canal is complete. 

6. Locomotion: Locomotion takes place with the help of setae (earthworm), parapodia (Nereis) or suckers (leech). Well developed longitudinal and circular muscles help in locomotion. 

7. Nervous system: It consists of nerve ring and ventral solid and ganglionated nerve cord. 

8. Reproduction: Mostly are hermaphrodites and few are dioecious (Nereis). 

9. Respiration: Exchange of gases takes place through body wall.

10. Circulation: Circulatory system is of closed type. Excretion and osmoregulation is carried out with help of nephridia. e.g. Nereis (Aquatic annelid), Pheretima (Earthworm), Hirudinaria (Leech).

Number of germ layers: 

(a) When an organism shows only two germ layers, they are called diploblastic animals. In this case, the outer ectoderm is separated from the inner endoderm by a non-living substance called mesoglea. (b) When an organism shows three germinal layers, they are called triploblastic animals. The three layers are namely – outer ectoderm, middle mesoderm and inner endoderm.

(d) ecdysone

(c) joint legs and chitinous exoskeleton

The nutrition in which solid food materials are taken in by animals is called holozoic nutrition.

Radiata: 

• These include radially symmetrical animals. 
• There are diploblastic e.g., Cnidarians and ctenophores

Bilateria: 

• These include bilaterally symmetrical animals. 
• There are triploblastic. e.g. Flat – worms

he development with different types of larval stages is called indirect development.