Name
(a) A limbless animal
(b) A cold blooded animal
(c) A warm blooded animal
(d) An animal possessing dry and cornified skin
(e) An animal having canal system and spicules
(f) An animal with cnidoblasts
(a) Ichthyophis does not possess limbs.
(b) Scoliodon (dog fish) is a cold blooded animal.
(c) Columba (pigeon) is a warm blooded animal.
(d) Naja naja (snake) possesses dry and cornified skin.
(e) Sycon (sponge) possesses canal system and bear spicules.
(f) Obelia bears cnidoblast.
Give an example for each of the following
(a) A viviparous animal
(b) A fish possessing a poison sting
(c) A fish possessing an electric organ
(d) An organ, which regulates buoyancy
(e) Animal, which exhibits alternation of generation
(f) Oviparous animal with mammary gland
(a) A viviparous animal is the one in which development of young ones is direct, later they provides nutrition to their offspring. It includes all mammals, except Platypus.
(b) A fish possessing a poison sting is Trygon (sting-ray). It is found on its tail. The poison released is strong enough to stun an animal.
(c) A fish possessing an electric organ Torpedo (electric ray). Electric organ in Torpedo is located in its big round pectoral fin which is just behind the eye. Large Torpedo can generate a fish killing current of up to 200 volts.
(d) An organ, which regulates buoyancy is air bladder present in class-Osteichthyes. (e.g., Exocoetus, Catla).
(e) Animal exhibiting alteration of generation is Aurelia or jelly fish of phylum-Cnidaria. It has two basic body forms called polyp and medusa are present. Polyp is sessile and cylindrical whereas medusa is umbrella shaped and free swimming form. Polyp produces medusa asexually and medusa forms polyps sexually (e.g., Obelia).
(f) Oviparous animal with mammary gland is Ornithorhynchus (duck-billed platypes). Duck bill platypus is the only mammal which lays egg and also bear mammary gland, which is a characteristic feature of mammals.
Excretory organs of different animals are given below. Choose correctly and write in the space provided.
| Animal | Excretory Organ/Unit | ||
|---|---|---|---|
| A. | Balanoglossus | (i) | Metanephridia |
| B. | Leech | (ii) | Nephridia |
| C. | Locust | (iii) | Flame cells |
| D. | Liver fluke | (iv) | Absent |
| E. | Sea urchin | (v) | Malpighian tubule |
| F. | Pila | (vi) | Proboscis gland |
A. $\rightarrow$ (vi) B. $\rightarrow$ (ii) C. $\rightarrow$ (v) D. $\rightarrow$ (iii) E. $\rightarrow$ (vi) F. $\rightarrow$ (i)
A. Balanoglossus - Proboscis glands This gland present in front of central sinus and excretes brown granules.
B. Leech Nephridia It helps in osmoregulation and excretion.
C. Locust Malpighian tubules These tubules open into gut and help in excretion.
D. Liver fluke Flame cells They are specialised cells in Platyhelminthes which helps in osmoregulation and excretion. These are also called protonephridia.
E. Sea urchin-absent Specialised excretory organs are absent in sea urchin.
F. Pila-Metanephridia It is a type of excretory gland or nephridium found in many types of invertebrates such as annelids, arthropods, and molluscs (in molluscs nephridia is also known as Bojanus organ).
Give three major differences between chordates and non chordates and draw a schematic sketch of a chordate showing those features.
The major differences between Chordates and Non-chordates are as follows
| Chordates | Non-Chordates | |
|---|---|---|
| 1. | A notochord is present at some stage in the life cycle of a chordate. | Notochord is not present at any stage in the life cycle of a non-chordate. |
| 2. | Gill-slits are present in the pharynx either in embryo or in adult organism. | Pharyngeal gill slits are absent. |
| 3. | Tail is present at some stage in the life of the chordate. | Tail is absent in non-chordates. |
| 4. | Heart is ventrally located. | Heart (if present) is dorsally located. |
| 5. | Central nervous system is dorsal and hollow in chordates. | Central nervous system in non-chordates is solid and ventrally located. |
Schematic sketch illustrating important characters of chordates is shown below
What is the relationship between germinal layers and the formation of body cavity in case of coelomate, acoelomates and pseudocoelomates?
All adult multicellular organisms typically possess a concentric arrangement of tissues in the body. These tissues are derived from the three embryonic cell layers called germinal layers.
(i) The outer layer is the ectoderm, the middle layer is the mesoderm and the innermost layer is the endoderm.
(ii) Endoderm layer is associated with the formation of the stomach, colon, liver, pancreas, urinary bladder and other vital organs in an organism.
(iii) Mesoderm forms the main structural components of the body like the skeletal muscles, the skeleton, the dermis of the skin connective tissue, etc.
(iv) Ectoderm is associated with the formation of CNS, eye lens, ganglia, nerves and glands.
(v) The body cavity that is lined by mesoderm is called coelom, and the animals possessing coelom are called as coelomates. e.g., phylum-Annelida, Mollusca, Arthropoda, Echinodermata, Hemichordata and Chordata.
(vi) In some organisms, body cavity is not lined by mesoderm, instead mesoderm is present in the form of scattered pouches in between ectoderm and endoderm, Such body cavity is called pseudocoelom and animals possessing there stusturs are refered to as pseudocoelomates e.g., Ascaris.
(vii) The animals in which there is complete absence of body cavity are called acoelomates. e.g., Platyhelminthes.
