1. Phylum
    2. 1. Classification of Animals
    2. Protozoa
    3. Porifera
    4. Coelenterata
    5. Platyhelminthes
    6. Nemathelminthes
    7. Annelida
    8. Earthworm
    9. Arthropoda
    10. Cockroach
    11. Mosquito
    12. Honey bee and Silk moth
    13. Mollusca
    14. Echinodermata
    15. Hemichordata
    16. Chordata
    17. Pisces
    18. Amphibia
    19. Frog
    20. Reptile
    21. Aves
    22. Mammalia
    23. Rabbit bone
  2. Animal Behaviour and Adaptation
    3. 24. Animal behaviour
    25. Animal adaptation
    26. Migration
  3. Developmental Biology
    4. 27. Development of Animals
    28. Development of Frog
  4. Human Biology
    5. 29. Tissues
    30. Sense organs
    31. Digestive system
    32. Circulatory system
    33. Respiratory system
    34. Nervous system
    35. Endocrine system
    36. Reproductive system
    37. Excretory system
    38. Skeletal system
    39. Basic concept of Immunology
    40. Human diseases
  5. Evolutionary Biology
    6. 41. Origin of Life
    42. Organic Evolution
    43. Theories of Evolution
    44. Evolution of Human beings
    45. Horse Evolution
Phylum
4. Coelenterata
COELENTERATA
▢ General Characters:
Image 1
Fig. Hydra
❖ Habit: Sessile or free swimming, Solitary or Colonial
❖ Habitat: Aquatic, mostly marine except few freshwater forms like Hydra
❖ Grade of Organization:
  1. Tissue grade of organization
  2. Presence of collection of bipolar and multipolar nerve cells forming an irregular net or plexus.
❖ Germ layers: Diploblastic
❖ Body cavity: Acoelomate
❖ Body plan: Blind sac body plan
❖ Symmetry: Radial symmetry except Sea anemone which is Biradial symmetrical.
1. Radial symmetry is found in

[MOE 2063]

  • Porifera
  • Coelenterata
  • Helminthes
  • Annelida
2. In sea anemone, the symmetry is
  • Radial
  • Spherical
  • Biradial
  • Bilateral
Image 1
❖ Nutrition: Carnivorous
❖ Digestion: Extracellular followed by intracellular
❖ Reproduction:
◉ Asexual methods:
  1. Budding or
  2. Strobilation
◉ Sexual methods:
◈ Larval forms:
  1. Hydra ->Hydralua
  2. Aurelia
    1. Hydratuba
    2. Scyphula
    3. Ephyra
1. Ephyra is the larva of
  • Obelia
  • Sea anemone
  • Physalia
  • Aurelia
❖ Receptors:
◉ Photoreceptor: Ocelli
◉ Statocysts: Balance receptors
1. Statocysts are found in
  • Paramecium
  • Obelia
  • Earthworm
  • Cockroach
▢ Body wall:
Consists of 2 cellular layers surrounding the Mesogloea
Image 1
❖ Epidermis (Outer epithelium):
❖ Gastrodermis (Inner epithelium):
  1. Lines the gastrovascular cavity
❖ Mesogloea:
  1. Extracellular gelatinous layer.
  2. Ranges from a thin, noncellular basal lamina to thick, fibrous, jelly-like, connective tissue with or without mesenchymal cells.
1. The body of coelenterates is made up of two cell layers. These are

[MOE 2000]

  • Epidermis and submucosa
  • Ectoplasm and endoplasm
  • Protoplasm and cytoplasm
  • Ectoderm and endoderm
2. Mesogloea is present in the phylum
  • Hydrozoa
  • Porifera
  • Annelida
  • Coelenterata
3. The middle layer of the body wall of Hydra is known as
  • Mesoderm
  • Gastrodermis
  • Glandulo-muscular layer
  • Mesogloea
▢ Gastrovascular cavity/ Coelenteron:
  1. This cavity serves as gut (for digestion of food) and as circulatory system (for circulation of digested body).
  2. Opens to outside at one end of body to form a mouth.
  3. Mouth serves both in ingestion and egestion.
  4. Anus is absent.
▢ Metagenesis/ Alternation of generation:
Alternation of polypoid and medusoid generation occurs.
❖ Example: Seen in Obelia of Hydrazoa class
Image 1
Credit. www.w3schools.blog
Image 1
Credit. www.w3schools.blog
Polypoid generation
Medusoid generation
Asexual generation
Sexual generation
No gonads is formed.
Gonads are present.
Sessile
Free swimming
Body is cylindrical with a long stalk.
Body is umbrella, cup shaped with reduced stalk.
Mesogloea is thin.
Mesogloea is thick.
Mouth is located in Hypostome.
Mouth is located in Manubrium.
Diploid
Diploid
1. Most appropriate term to describe the life cycle of hydrozoans like Obelia is
  • Alternation of generation
  • Neoteny
  • Metagenesis
  • Metamorphosis
2. Metagenesis occurs in
  • Hydra
  • Obelia
  • Aurelia
  • Tubipora
▢ Polymorphism:
Image 1
Fig. A -> Obelia; B->Hydractinia; C->Vella; D->Physalia;
E->Generalized calycophoran Siphonophora
The occurrence of structurally and functionally different types of individuals, called zooids, within the same organism during its life history is called Polymorphism.
❖ Example: Seen in Physalia of Class of Hydrazoa
❖ 9 types:
◉ Trophozooid/ Gastrozooid: Feeding
◉ Gonophore: Sessile medusae
◉ Gonozooid: Gonophore production
◉ Dactylozooid: Protection, food caption
◉ Tentaculozooid: Same as dactylozooid
◉ Nematophore: Food capture
◉ Pneumatophore: Float
◉ Nectophore: Swimming
◉ Phyllozooid: Protective cover
1. Polymorphism is characteristics of the phylum:

[IOM 2005]

  • Annelida
  • Coelenterata
  • Porifera
  • Protozoa
2. Polymorphism is found

[BPKIHS 2001]

  • Hydra
  • Coral
  • Physalia
  • Sponges
3. Polymorphism is characteristics of the phylum:

[IOM 2013]

  • Coelenterata
  • Annelida
  • Porifera
  • Protozoa
4. Polymorphism occurs in
  • Anthozoa
  • Scyphozoa
  • Rhizopod
  • Hydrozoa
▢ Nematocyst and Tentacles:
❖ Tentacles surround the mouth to aid in capture and ingestion of food.
❖ Cnidocyte/ Cnidoblast: It is cell of cnidarians containing cnide.
❖ Cnide:
  1. Cnide are cellular organelles of cnidocyte.
  2. It is capable of eversion from cnidocyte.
  3. It is of 3 types of which one type is Nematocyst.
▢ Coral reef formation:
1. Coral reef is formed by

[IOM 2013]

  • Coelenterata
  • Echinodermata
  • Mollusca
  • Annelida
2. Coral reef is formed by

[IOM 2013]

  • Echinoderm
  • Helminthes
  • Mollusca
  • Coelenterates
▢ Classification:
Characters
Hydrozoa (Water)
Scyphozoa (Cup shaped Medusa)
Anthozoa (Flower shaped)
Habitat
Few fresh water and most are marine
Marine
Marine
Zooids
Both Polyp and Medusa. In Hydra only Polyp. In Obelia both Polyp and Medusa are present (So Metagenesis)
Medusa
Polyp
Mesogloea
Thin (Dominant) Without chamber
Thick Without chamber
Thin Chambered
Metagenesis
Yes (Both Polyp and Medusa form of zooid present in their life cycle)
No
No
Polymorphism
Yes. E.g.: Physalia (Portuguese man of war):
No
Examples
  1. Hydra
    2. Image 1
  2. Obelia (Sea fur)
    3. Image 1
    ◈ Metagenesis
  3. Physalia (Portuguese man of war)
    4. Image 1
    ◈ Polymorphism
  4. Velella (Little sail)
    5. Image 1
  5. Porpita (Blue button)
    6. Image 1
  6. Mililipora (Fire coral)
    7. Image 1
  7. Bougainvilla (a plant also with same name)
    8. Image 1
  1. Aurelia (Jellyfish)
    • •
      Aurelia is Bioluminiscent.
    Image 1
  1. Metridium (Sea anemone)
    2. Image 1
  2. Adamsia (Sea anemone)
    3. Image 1
  3. Alcyonium (Dead man's finger)
    4. Image 1
  4. Gorgonia (Sea fan)
    5. Image 1
  5. Pennatula (Sea pen/ Sea feather)
    6. Image 1
  6. Fungia (Mushroom coral)
    7. Image 1
  7. Heliopora (Blue coral)
    8. Image 1
  8. Astraea (Star coral)
    9. Image 1
  9. Madrepora (Horny coral)
    10. Image 1
  10. Tubipora (Organ pipe coral)
    11. Image 1
  11. Corallium (Precious Red coral/ Coral stone)
    12. Image 1
  12. Meandrina (Brain coral)
    13. Image 1
  13. Virgularia (Walking stick)
    14. Image 1
  14. Charybdaea (Sea wasp)
    15. Image 1
1. Scyphozoan medusa is more commonly known as

[IE 2002]

  • Hydra
  • Sea anemone
  • Jelly fish
  • Corals
2. In which class Jellyfish is found?

[BPKIHS 2013, BPKIHS 2014]

  • Scyphozoa
  • Hydrozoa
  • Anthozoa
  • Sporozo
3. Which is a coelenterate
  • Sea pen
  • Sea urchin
  • Sea fish
  • Sea cucumber
4. Which group does not contain polyp
  • Hydrozoa
  • Scyphozoa
  • Anthozoa
  • Calcarea
5. The generic name of common jellyfish is
  • Aurelia
  • Physalia
  • Gorgonia
  • Pennatula
6. Sea anemone belongs to the class
  • Coelenterata
  • Hydrozoa
  • Scyphozoa
  • Anthozoa/Actinozoa
7. Organ pipe coral is
  • Fungia
  • Tubipora
  • Heliopora
  • Astraea
8. Gastrovascular cavity is divided into compartments in
  • Hydrozoa
  • Scyphozoa
  • Anthozoa
  • None
9. Only asexual polyp stage occurs in
  • Hydrozoans
  • Scyphozoans
  • Anthozoans
  • All
10. Which one of these is cnidarian?
  • Sea urchin
  • Sea horse
  • Sea cucumber
  • Sea anemone
11. Which one of these is cnidarian?
  • Sea anemone
  • Sea fan
  • Sea pen
  • All
HYDRA
▢ General Characters:
❖ Habit: Solitary
❖ Habitat: Freshwater (stagnant)
❖ Grade of Organization: Tissue-grade of body organization
❖ Germ layers:
◉ Diploblastic
◉ Ectoderm:
    ◉ Endoderm/ Gastroderm:
      ◉ Mesogloea:
      1. Found between ectoderm and endoderm
      2. Secreted by both ectoderm and endoderm
      3. Thin, delicate, transparent and noncellular.
      1. Mesogloea in Hydra is secreted by
      • Epidermis
      • Gastrodermis
      • Both of these
      • Hypostome
      ❖ Symmetry: Radially symmetrical
      ❖ Coelom: Acoelomate
      ❖ Body plan: Blind sac body plan due to presence of Hypostome but lacks Anus.
      ❖ Segmentation: Unsegmented
      ❖ Symbiotic relation with Chlorella:
      1. No chlorophyll.
      2. Green due to presence of Chlorella vulgaris(Zoochlorella)
      3. Zoochlorella is intracellular symbiont.
      4. It lives in Musculoepithelial cells of Hydra.
      1. An association mutually benefited to both partners is represented by
      • Hydro and waterfleas
      • Zoochlorella and Hydra
      • Earthworm and farmer
      • Honeybee and man
      ▢ Body parts:
      ❖ Hypostome:
      1. Mouth of Hydra
      2. Also called as Manubrium
      ❖ Basal disc: Attached to substratum
      ❖ Tentacles:
      1. Surround the mouth to aid in capture and ingestion of food.
      2. Also help in locomotion.
      3. So, analogous to to pseudopodia of Amoeba.
      4. Tentacles of hydra are hollow.
      5. Growth zone of hydra is located just below the tentacles.
      1. The tentacles of Hydra are
      • Solid
      • Hollow
      • Branched
      • Frilled
      2. Number of tentacles in Hydra is
      • Two to four
      • Six to ten
      • Ten to forty
      • Forty to fifty
      3. The growth zone of Hydra is located
      • Just below the tentacles
      • In the middle of the hard.
      • In the hypostome
      • Around the basal disc
      ❖ Coelenteron:
      1. Also called Gastrovascular cavity.
      2. Endodermis/ Gastrodermis lines it.
      3. Serves the function of Digestion and Circulation.
      ▢ Body wall:
      ▢ Cells:
      Image 1
      Fig. Cells in Hydra
      Cell Type
      Epidermis
      Gastrodermis
      Muscular cells
      ▢ Epithelio-muscular cell: If forms the bulk of Epidermis
      ▢ Endothelio-muscular cell: If forms the bulk of Endodermis
      Interstitial cells
      1. Present
      2. But absent in Epidermis of pedal disc and tentacles.
      3. Undifferentiated cells that can develop into other cell types
      Present
      Nerve cells
      Present - Form nerve nets for simple sensory functions
      Present - Similar nerve nets found, coordinating with epidermal nerve nets
      Sensory cell
      Present
      Present
      Gland cells
      Epithelio-gland cell
      Endothelio-gland cell - Secrete digestive enzymes into the gastrovascular cavity
      Cnidocytes
      Present - Stinging cells used for defense and prey capture
      Absent
      Germ cell
      Present
      Absent
      1. Which of the following is only present in epidermis of Hydra:

      [IOM 2005]

      • Muscular cells
      • Sensory cell
      • Nematoblasts
      • Interstitial cells
      2. Hydra will regenerate from a fragement, if it contains
      • Tentacles
      • Epidermis and gastrodermis
      • Tentacles, epidermis and gastrodermis
      • Epidermis, hypodermis and gastrodermis
      3. Which pair of cells is present in the epidermis of Hydra but not, in the endoderm?
      • Stinging cells and gland cells
      • Stinging cells and germ cells
      • Gland cells and germ cells
      • Stinging cells and interstitial cells
      ❖ Cnidocytes:
      Image 1
      ◉ Features of Cnidoblast:
      1. Universal character of all coelenterates.
      2. Derived from interstitial cells of epidermis.
      3. Present only in epidermis.
      4. Maximum in tentacles.
      5. Absent in pedal disc / basal disc.
      6. A group of cnidoblasts is known as Cnidome.
      7. The group of cnidoblasts on the tentacles is especially called Battery.
      8. Opening of nematocyst is Operculum.
      9. Just below the operculum, narrow neck is Butt.
      10. Inside the butt, triangular shaped structure is Barb.
      Type and Name
      Features and Functions
      Penetrant / Stenoteles - Largest Nematocyst
      1. Discharges a thread tube that injects poisonous fluid (hypnotoxin)
      2. Hypnotoxin paralyzes or kills prey like Cyclops and Daphnia
      3. Hypnotoxin is composed of protein and phenol
      4. Makes Cnidarians carnivorous
      5. Most complex type of nematoblast
      Volvent / Desmoneme - Smallest Nematocyst
      1. Thread coils tightly around projections such as hair or bristles
      2. Coils and captures prey
      Glutinant / Holotrichous isorhiza (Streptoline glutinant) - Largest glutinant
      • Used to stick to prey
      Glutinant / Atrichous isorhiza (Steroline glutinant) - Smallest glutinant
      1. Helps in looping movement
      2. Common mode of locomotion in Hydra
      3. Looping movement is leech-like in Hydra
      4. Somersaulting movement is the fastest locomotion mode
      ◉ Grouping of Cnidoblasts:
      1. A group of cnidoblasts is known as Cnidome.
      2. The group of cnidoblasts on the tentacles is especially called Battery.
      ◉ Structure of Nematocyst:
      1. Opening of nematocyst is Operculum.
      2. Just below the operculum, narrow neck is Butt.
      3. Inside the butt, triangular shaped structure is Barb.
      ◉ Functions of Nematoblast:
      1. Takes part in locomotion, food capture, offence, and defence.
      ◉ Nematocyst Details:
      1. Nematocyst or stinging capsule is a part of the cell called Cnidoblast or Cnidocyte.
      2. Nematocyst is known as Independent effector:
      3. Discharge of nematocyst is completely independent of nervous control, hence called independent effector.
      4. Discharge of nematocyst is enzymatic in action.
      5. Discharge involves both mechanical and chemical stimulus.
      6. On stimulation, the nematocyst shoots out within 0.3–0.5 seconds.
      7. Action depends on enzymes that increase osmotic pressure inside the capsule.
      8. Once flagellum is used, it is never withdrawn — nematocyst is used only once.
      ◉ Supportive Structures:
      1. Lasso, bars (3 pairs of large spines), and barbules (50 pairs of smaller spines).
      2. Lasso helps in checking the emerging of nematocyst.
      ◉ Cnidocil:
      1. The trigger needle of cnidoblast is called Cnidocil.
      2. Cnidocil is the stimulus-receiving part of nematoblast / cnidoblast.
      1. Poison present in Nematocyst of Hydra is:

      [IOM 2000]

      • Haematin
      • Hirudin
      • Heparin
      • Hypnotoxin
      2. Which is toxic substance secreted by Hydra?

      [BPKIHS 2013]

      • Hirudin
      • Hypnotoxin
      • Heparin
      • Histamine
      3. Penetrants and stenoteles are names of nematocysts in phylum coelenterata of these:

      [BPKIHS 2005]

      • Penetrants are smaller
      • Penetrants are larger
      • Both are same
      • Stenoteles are not found in Hydra
      4. Common between trichocysts of Paramecium and nematocysts of Hydra is
      • Attachment and defence
      • Defence only
      • Sensitivity
      • Food capturing
      5. Characteristics cells of Hydra is
      • Trichocys
      • Nematocyst
      • Cnidoblast
      • Sporocyst
      6. Hydra is a coelenterate because it posses
      • Mesogloea
      • Nematocyst
      • Body cavity
      • Tentacles
      7. Which action of Hydra will be most hindered if there were no nematocysts in it?
      • Locomotion
      • Food capture
      • Digestion
      • Ingestion
      8. Hypnotoxin is a poisonous fluid produced by
      • Ascaris
      • Ants
      • Parasitic protozoa
      • Nematocysts
      9. Nematocysts take part in
      • Locomotion
      • Offence and Defence
      • Food capture
      • All of these
      10. A group of cnidoblast is called
      • Bunch
      • Aggregation
      • Clone
      • Battery
      11. Largest nematocyst of Hydra is
      • Volvent
      • Penetrant
      • Atrichous isorhiza
      • Holotrichous isorhiza
      12. Common between trichocyst of paramecium and nematocyst of Hydra is
      • Attachment and defence
      • Defence only
      • Sensitivity
      • Food capturing
      13. The 'independent effectors' of Hydra are
      • Nerve cells
      • Sensory cells
      • Gland cells
      • Nematocysts
      ❖ Interstitial cell:
      ◉ About:
      1. Interstitial cell is a totipotent cell.
      2. So, interstitial cells help in regeneration called Morpholaxis.
      3. Interstitial cell can transform into all other types of cells including germ/sex cell, glandular cell, and cnidoblast.
      ◉ Cell Types Derived from Interstitial Cells:
      1. Reproductive cells
      2. Glandular cells
      3. Stinging cells (Cnidoblasts)
      ◉ Scientific View:
      1. Brien stated that all cells arise from interstitial cells.
      ◉ Functions of Interstitial Cells:
      1. Help in formation of external bud.
      ◉ Characteristics of Interstitial Cells:
      1. Interstitial cells are uninucleated.
      2. Interstitial cells are absent in the epidermis of pedal disc and tentacles.
      3. Interstitial cells can cross the mesoglea.
      1. Cells of Hydra having capacities of regeneration, repair and budding are
      • Interstitial
      • Gastrodermis
      • Blepharoplast
      • Cnidocils
      ❖ Epithelio-muscular cell:
      ◉ Epithelio-muscular Cell:
      1. Epithelio-muscular cell forms the bulk of the epidermis.
      ◉ Structure of Epithelio-muscular Cell:
      1. Muscle tail or Myoneme is present in it.
      2. The number of myonemes in the muscle tail of epithelio-muscular cells is two.
      ◉ Function of Epithelio-muscular Cell:
      1. Contraction of muscle fibres in the epithelio-muscular cells shortens the body and tentacles.
      Part
      Features and Functions
      Epithelial Part
      1. Located towards the epidermis side
      2. Helps in cuticle formation (Cuticle → Epidermis → Mesoglea → Endodermis)
      3. Provides protection
      Muscular Part
      1. Located towards the mesoglea side
      2. Helps in shortening and bending of the body
      3. Responsible for body movement
      1. Muscles of Hydra are
      • Smooth
      • Skeletal
      • Both a and b
      • None of the above
      ❖ Epithelio-gland cell:
      ◉ Epithelio-gland Cells / Glandulo-muscular Cell:
      1. Also known as Glandulo-muscular cell
      2. Glandulo-muscular cell is a modification of epithelial-muscular cells.
      3. Glandulo-muscular cell is maximum in epidermis, pedal/basal disc.
      ◉ Functions of Glandulo-muscular Cells:
      1. Help in attachment.
      2. Create gas bubbles that make it float (floating movement).
      ❖ Sensory cell:
      ◉ Sense organs like Statocyst, Tentaculocyst occur in free swimming forms.
      1. In Hydra, Sensory cell found in:
      • Tentacles
      • Pedal stalk
      • Hypostome
      • All
      ❖ Nerve cell:
      ◉ Nerve Cell:
      1. Nerve cells are apolar.
      2. Nerve cells are more numerous in the epidermis of hypostome, basal disc, and basal parts of tentacles.
      ◉ Stimuli Responded to by Nerve Cells:
      1. Touch
      2. Chemical
      3. Temperature
      4. Light
      5. Electric current
      6. No response to rheotaxis
      ◉ Nervous System:
      1. Nervous system is a simple nerve net, made of naked and largely nonpolar neurons.
      ◉ Endocrine Role:
      1. Endocrine system is also present, and hormones are secreted by nerves.
      ❖ Germ cell:
      ▢ Physi:
      ❖ Locomotion:
      1. Walking
        1. Erect movement with all tentacles directed downwards using them as legs.
        2. It is called Cuttlefish movement because it resembles the locomotion of cuttlefish.
      2. Gliding
        1. Slowest mode of locomotion
      3. Floating
      4. Looping or Somersaulting
        1. Most common mode of locomotion in hydra.
        2. Fastest mode of locomotion.
      1. Which structure in Hydra functionally corresponds to the pseudopodia of Amoeba
      • Tentacles
      • Mouth
      • Nematocyst
      • Hypostome
      2. Hydra sometimes move upon its tentacles using them as legs. This is known as
      • Looping
      • Gliding
      • Walking
      • None
      ❖ Nutrition:
      ◉ Food:
      1. Exclussively carnivorous, and feeds only on Crustaceans.
      2. Favourit food is Water fleas (Daphnia and Cyclops)
      3. Recognizes its prey by the presence of Glutathione in the tissue fluid of the prey.
      ◉ Digestion:
      1. Extracellular followed by Intracellular.
      2. Can digest Carbohydrate, Fats and Proteins.
      3. No enzymes for Starch so can't digest Starch.
      1. The food which Hydra can't digest is

      [MOE 2054]

      • Fat
      • Starch
      • Protein
      • Lipid
      2. Gastrodermis of Hydra takes part in digestion of
      • Carbohydrate and fats
      • Proteins and fats
      • Proteins and carbohydrate
      • Proteins, fats and some carbohydrate
      3. The mouth of Hydra is opened by the chemical influence of
      • Glucagon
      • Glutamic acid
      • Glutathione
      • Gluanine
      4. Hydra recognizes its prey by
      • Special organs
      • Nematocyst
      • Chemical secreted by prey
      • Mechanical stimulus of prey
      ❖ Respiration: General body surface
      ❖ Circulation: Diffusion.
      1. Absence of circulatory system in Hydro is compensated by
      • Pseudocoelomic fluid
      • Gastrovascular cavity
      • Presence of tentacles
      • None
      ❖ Excretion: Through General Body surface
      ❖ Excretory product: Ammonia
      ❖ Osmoregulation: Through General Body surface.
      ❖ Nervous system:
      1. Absence of Brain, only nerve nets are present
      2. Nerve nets are formed by nerve cells and nerve processes.
      3. Unpolarized nerve nets.
      1. Which of the following has nervous system but no brain?

      [IOM 2014]

      • Amoeba
      • Fasciola
      • Taenia
      • Hydra
      ❖ Sensory receptors:
      ◉ Sensory cells:
      1. Most numerous on Tentacles, Hypostome and around the basal disc.
      2. Each sensory cells extends from the nerve net to body surface.}
      ◉ Photoreceptor:
      1. Prefers the region of moderate light.
      2. So responds negatively to both strong and weak light.
      ◉ Reoreceptor: No reaction to water current.
      ◉ Galvanoreceptor: In electric field, tentacular end of Hydra bends towards anode and pedal disc to cathode.
      ◉ Chemorecepor: -vely chemotropic, and avoid chlorinated water.
      1. Hydra possesses
      • Sensory cells but no nerve cells
      • Nerve cells but not sensory cells
      • Both sensory and nerve cells
      • None
      ❖ Reproduction:
      ◉ Asexual methods:
      1. Budding
        1. During favourable condition when plenty of food and water are available.
      ◉ Sexual methods:
      1. Occurs during unfavourable condition when lack of food and water.
      2. Most of the species are Monoecious/hermaphrodite.
      3. Bisexual species of Hydra are Protandrous, so avoids self-fertilization; cross fertilization is the rule.
      4. There is Single ovary and Many testes.
      5. Ovary of hydra posses one ovum.
      6. Fertilization occurs externally on the body by the entry of sperm into ovum.
      7. If sperm enters the coelenteron of Hydra, it will be digested.
      8. Hydra has direct development, but a larva-like structure is present called Hydraula or Hydratuba.
      9. Common larva of cnidarians is Planula, especially in jellyfish, Obelia, and sea anemone.
      1. Budding in Hydra is:

      [IE 2005, IOM 2068]

      • Asexual reproduction
      • Sexual reproduction
      • Binary fission
      • Parthenogenesis
      2. Self fertilization is absent in Hydra due to:

      [IOM 2016]

      • Monoecious
      • Hermaphrodite
      • Protandrous
      • Protogynous
      3. A number of buds have developed on Hydra
      • Oldest bud is towards oral region
      • Oldest bud is towards aboral region
      • Both a and b
      • There is no order
      4. A single mature Hydra may bear
      • One ovary, one testes
      • Several ovaries, one testes
      • One ovary, several testes
      • Several ovaries, several testes
      5. Hydra reproduces by budding when
      • It is alone
      • Plenty of food is available
      • Population of Hydra in pond increases
      • Environmental conditions are unfavourable
      6. The type of asexual reproduction found in Hydra is
      • Budding
      • Multiple fission
      • Sporulation
      • Binary fission
      ❖ Regeneration:
      ◉ Epimorphosis: Tentacles/ Body part of hydra regenerates by Epimorphosis.
      ◉ Morphollaxis: Hydra regenerates by Morphollaxis.
      1. Hydra regenerates by:

      [IOM 2002]

      • Compensatory hypertrophy
      • Morphollaxis
      • Epimorphosis
      • Autotomy
      2. If Hydra is broken down into pieces
      • Hydra will undergo sexual reproduction
      • Hydra will grow into complete Hydra
      • Some fragments will form complete hydra
      • Hydra will die
      ❖ Special points:
      ◉ Symbiotic Relationships:
      1. Sea anemone (Metridium) and hermit crab: Commensalism (+, 0).
      2. Euplectella and Spongicola: Commensalism (+, 0).
      3. Hydra and Zoochlorella or Zooxanthophylla: Symbiosis (+, +).
      1. The food which Hydra can't digest is

      [MOE 2054]

      • Fat
      • Starch
      • Protein
      • Lipid
      2. Which of the following is only present in epidermis of Hydra:

      [IOM 2005]

      • Muscular cells
      • Sensory cell
      • Nematoblasts
      • Interstitial cells
      3. Polymorphism is characteristics of the phylum:

      [IOM 2005]

      • Annelida
      • Coelenterata
      • Porifera
      • Protozoa
      4. Hydra regenerates by:

      [IOM 2002]

      • Compensatory hypertrophy
      • Morphollaxis
      • Epimorphosis
      • Autotomy
      5. Poison present in Nematocyst of Hydra is:

      [IOM 2000]

      • Haematin
      • Hirudin
      • Heparin
      • Hypnotoxin
      6. Radial symmetry is found in

      [MOE 2063]

      • Porifera
      • Coelenterata
      • Helminthes
      • Annelida
      7. The body of coelenterates is made up of two cell layers. These are

      [MOE 2000]

      • Epidermis and submucosa
      • Ectoplasm and endoplasm
      • Protoplasm and cytoplasm
      • Ectoderm and endoderm
      8. Polymorphism is found

      [BPKIHS 2001]

      • Hydra
      • Coral
      • Physalia
      • Sponges
      9. Penetrants and stenoteles are names of nematocysts in phylum coelenterata of these:

      [BPKIHS 2005]

      • Penetrants are smaller
      • Penetrants are larger
      • Both are same
      • Stenoteles are not found in Hydra
      10. Scyphozoan medusa is more commonly known as

      [IE 2002]

      • Hydra
      • Sea anemone
      • Jelly fish
      • Corals
      11. Budding in Hydra is:

      [IE 2005, IOM 2068]

      • Asexual reproduction
      • Sexual reproduction
      • Binary fission
      • Parthenogenesis
      12. Coral reef is formed by

      [IOM 2013]

      • Coelenterata
      • Echinodermata
      • Mollusca
      • Annelida
      13. In which class Jellyfish is found?

      [BPKIHS 2013, BPKIHS 2014]

      • Scyphozoa
      • Hydrozoa
      • Anthozoa
      • Sporozo
      14. Which is toxic substance secreted by Hydra?

      [BPKIHS 2013]

      • Hirudin
      • Hypnotoxin
      • Heparin
      • Histamine
      15. Which of the following has nervous system but no brain?

      [IOM 2014]

      • Amoeba
      • Fasciola
      • Taenia
      • Hydra
      16. Coral reef is formed by

      [IOM 2013]

      • Echinoderm
      • Helminthes
      • Mollusca
      • Coelenterates
      17. Polymorphism is characteristics of the phylum:

      [IOM 2013]

      • Coelenterata
      • Annelida
      • Porifera
      • Protozoa
      18. Self fertilization is absent in Hydra due to:

      [IOM 2016]

      • Monoecious
      • Hermaphrodite
      • Protandrous
      • Protogynous
      19. Which is a coelenterate
      • Sea pen
      • Sea urchin
      • Sea fish
      • Sea cucumber
      20. In sea anemone, the symmetry is
      • Radial
      • Spherical
      • Biradial
      • Bilateral
      21. Muscles of Hydra are
      • Smooth
      • Skeletal
      • Both a and b
      • None of the above
      22. Common between trichocysts of Paramecium and nematocysts of Hydra is
      • Attachment and defence
      • Defence only
      • Sensitivity
      • Food capturing
      23. Which group does not contain polyp
      • Hydrozoa
      • Scyphozoa
      • Anthozoa
      • Calcarea
      24. A number of buds have developed on Hydra
      • Oldest bud is towards oral region
      • Oldest bud is towards aboral region
      • Both a and b
      • There is no order
      25. Polymorphism occurs in
      • Anthozoa
      • Scyphozoa
      • Rhizopod
      • Hydrozoa
      26. Characteristics cells of Hydra is
      • Trichocys
      • Nematocyst
      • Cnidoblast
      • Sporocyst
      27. Most appropriate term to describe the life cycle of hydrozoans like Obelia is
      • Alternation of generation
      • Neoteny
      • Metagenesis
      • Metamorphosis
      28. Hydra will regenerate from a fragement, if it contains
      • Tentacles
      • Epidermis and gastrodermis
      • Tentacles, epidermis and gastrodermis
      • Epidermis, hypodermis and gastrodermis
      29. Which structure in Hydra functionally corresponds to the pseudopodia of Amoeba
      • Tentacles
      • Mouth
      • Nematocyst
      • Hypostome
      30. Hydra is a coelenterate because it posses
      • Mesogloea
      • Nematocyst
      • Body cavity
      • Tentacles
      31. Metagenesis occurs in
      • Hydra
      • Obelia
      • Aurelia
      • Tubipora
      32. Mesogloea is present in the phylum
      • Hydrozoa
      • Porifera
      • Annelida
      • Coelenterata
      33. Statocysts are found in
      • Paramecium
      • Obelia
      • Earthworm
      • Cockroach
      34. The generic name of common jellyfish is
      • Aurelia
      • Physalia
      • Gorgonia
      • Pennatula
      35. Sea anemone belongs to the class
      • Coelenterata
      • Hydrozoa
      • Scyphozoa
      • Anthozoa/Actinozoa
      36. Organ pipe coral is
      • Fungia
      • Tubipora
      • Heliopora
      • Astraea
      37. The tentacles of Hydra are
      • Solid
      • Hollow
      • Branched
      • Frilled
      38. Number of tentacles in Hydra is
      • Two to four
      • Six to ten
      • Ten to forty
      • Forty to fifty
      39. Mesogloea in Hydra is secreted by
      • Epidermis
      • Gastrodermis
      • Both of these
      • Hypostome
      40. The middle layer of the body wall of Hydra is known as
      • Mesoderm
      • Gastrodermis
      • Glandulo-muscular layer
      • Mesogloea
      41. Which action of Hydra will be most hindered if there were no nematocysts in it?
      • Locomotion
      • Food capture
      • Digestion
      • Ingestion
      42. Hypnotoxin is a poisonous fluid produced by
      • Ascaris
      • Ants
      • Parasitic protozoa
      • Nematocysts
      43. Nematocysts take part in
      • Locomotion
      • Offence and Defence
      • Food capture
      • All of these
      44. Gastrodermis of Hydra takes part in digestion of
      • Carbohydrate and fats
      • Proteins and fats
      • Proteins and carbohydrate
      • Proteins, fats and some carbohydrate
      45. The mouth of Hydra is opened by the chemical influence of
      • Glucagon
      • Glutamic acid
      • Glutathione
      • Gluanine
      46. Which pair of cells is present in the epidermis of Hydra but not, in the endoderm?
      • Stinging cells and gland cells
      • Stinging cells and germ cells
      • Gland cells and germ cells
      • Stinging cells and interstitial cells
      47. If Hydra is broken down into pieces
      • Hydra will undergo sexual reproduction
      • Hydra will grow into complete Hydra
      • Some fragments will form complete hydra
      • Hydra will die
      48. Hydra sometimes move upon its tentacles using them as legs. This is known as
      • Looping
      • Gliding
      • Walking
      • None
      49. A group of cnidoblast is called
      • Bunch
      • Aggregation
      • Clone
      • Battery
      50. Largest nematocyst of Hydra is
      • Volvent
      • Penetrant
      • Atrichous isorhiza
      • Holotrichous isorhiza
      51. Hydra recognizes its prey by
      • Special organs
      • Nematocyst
      • Chemical secreted by prey
      • Mechanical stimulus of prey
      52. A single mature Hydra may bear
      • One ovary, one testes
      • Several ovaries, one testes
      • One ovary, several testes
      • Several ovaries, several testes
      53. Hydra possesses
      • Sensory cells but no nerve cells
      • Nerve cells but not sensory cells
      • Both sensory and nerve cells
      • None
      54. Absence of circulatory system in Hydro is compensated by
      • Pseudocoelomic fluid
      • Gastrovascular cavity
      • Presence of tentacles
      • None
      55. Common between trichocyst of paramecium and nematocyst of Hydra is
      • Attachment and defence
      • Defence only
      • Sensitivity
      • Food capturing
      56. Hydra reproduces by budding when
      • It is alone
      • Plenty of food is available
      • Population of Hydra in pond increases
      • Environmental conditions are unfavourable
      57. Gastrovascular cavity is divided into compartments in
      • Hydrozoa
      • Scyphozoa
      • Anthozoa
      • None
      58. The growth zone of Hydra is located
      • Just below the tentacles
      • In the middle of the hard.
      • In the hypostome
      • Around the basal disc
      59. An association mutually benefited to both partners is represented by
      • Hydro and waterfleas
      • Zoochlorella and Hydra
      • Earthworm and farmer
      • Honeybee and man
      60. Only asexual polyp stage occurs in
      • Hydrozoans
      • Scyphozoans
      • Anthozoans
      • All
      61. Ephyra is the larva of
      • Obelia
      • Sea anemone
      • Physalia
      • Aurelia
      62. In the development of Hydra, gastrulation is the result of
      • Delamination
      • Emboly
      • Epiboly
      • Invagination
      63. The type of asexual reproduction found in Hydra is
      • Budding
      • Multiple fission
      • Sporulation
      • Binary fission
      64. The 'independent effectors' of Hydra are
      • Nerve cells
      • Sensory cells
      • Gland cells
      • Nematocysts
      65. Cells of Hydra having capacities of regeneration, repair and budding are
      • Interstitial
      • Gastrodermis
      • Blepharoplast
      • Cnidocils
      66. Which one of these is cnidarian?
      • Sea urchin
      • Sea horse
      • Sea cucumber
      • Sea anemone
      67. Which one of these is cnidarian?
      • Sea anemone
      • Sea fan
      • Sea pen
      • All