Question

Q.5. Give a brief description of the following pairs of terms: a). Diploblastic vs. Triploblastic b). Choanocyte vs. Choanoflagellate c). Protist vs. Animal d). Acoelomate vs. Pseudocoelomate Q.6. What are the characteristic features of the following taxa? a). Cestoda b). Nematoda c). Rotifera d). Platyhelminthes Q.7. Describe the traits which define Phylum Chordata? Q.8. List four observable characteristics of each type of vertebrate a). Chondrichthyes b). Amphibians c). Reptiles d). Mammals

Answer 1

ANSWER :

5 (a)

Diplobastic	Triploblastic
1.Diploblastic animals are made up of two primary germ layers-ectoderm and endoderm during gastrulation.	1.Triploblastic animals are made up of three primary germ layers namely- ectoderm, mesoderm and endoderm
2. They are generally radially symmetrical	2. They are generally bilaterally symmetrical

3.They donot possess any body cavity i.e coelom .

3. They develop body cavity i.e coelom.

(b)

Choanocyte	Choanoflagellate
1. Choanocyte are cells that forms the interior lining of the asconoid, leuconoid and syconoid types of sponges.	1. Choanoflagellate i a group of free living unicellular eukaryotes which are considered to be closest relatives of animals.

(c)

Protist	Animal
1.Protist are a large group of unicellular eukaryotic organism with a true membrane bound nucleus	1.Animal cells are basic unit of life in organism of kingdom Animalia.They are eukaryotic in nature and lacks a cell wall.
2.They can be distinguished from animal cell by their ability to move from one place to other with the help of flagella.	2. The animal cells are immobile.

(d)

Acoelomate	Pseudocoelomate
1. Acoelomate lacks true body cavity, between the body wall and the digestive tract.	1. Pseudocoelomate have pseudocoelom , that is they have a false body cavity which is not lined with mesoderm.
2. Example- Phylum Cnidaria (Sea anemones)	2. Example -Phylum Nematoda (roundworms.)

6. (a)The characteristic features of Cestoda  are -

(i) They have tape-like or ribbon-like and have a segemented body(each unit called proglottids) commonly known as parasitic worms or tape worms.

(ii) They are generally hermaphrodites .

(iii) They are acoelomate (lacks a true body cavity) and lacks a digestive tract.

(iv) Common examples are - Taenia solium, Taenia sagginata.

(b)The characteristic features of Nematoda  are -

(i) The body of nematodes are bilaterally symmetrical and triploblatic in nature.

(ii) They have a tissue level organisation.and exhibit a cylindrical structure.

(iii) They are pseudocoelomate and thus lacks a true body cavity.

(iv) They are sexually dimorphic in nature.

(v) Common examples- Trichinella ,Enterobius

(c)The characteristic features of Rotifera are -

(i) The rotifers are microscopic , unicellular, psuedocoelomate , bilaterally symmetrical and aquatic in nature.

(ii) The unique characteristic of this group is presence of rotating wheel like structure on their head known as corona.

(iii) The jawed pharynx also known as mastax is also dinctive feature of  this group.

(iv)Common example - Branchionus

(d)The characteristic features of Platyhelminthes are -

(i) They are acoelomate i.e lacks a ,true body cavity,triploblastic and bilaterally symmetrical.

(ii)They have organ-system level of organization

(iii) The body is soft, dorsoventrally flattened and unsegmented .

(iv)Common exampes- Planaria

7. The traits that define phylum chordata -

(i) The presence of dorsally located notochord, which is derived from dorsal wall of embryonic gut.

(ii) The presence of dorsal , hollow tubular nerve-cord ,produced from invagination of the neural cells of ectoderm.

(iii)The presence of post-anal tail , which is an exception in adult urochordates.

(iv) The presence of pharyngeal slits , which helps in filtering and respiration in the primitive groups.

8. The observable characteristic of -

(a)Chondricthyes-

(i)The endoskeleton is entirely cartilaginous

(ii) They have tough skin covered with their dermal teeth.

(iii) In almost most of the species the dermal denticles also called placoid scales are oriented in one direction.

(iv)They have about five to seven pairs of gills .

(b)Amphibians-

(i)Most of the amhibians have moist , soft , permeable and scaleless skin and breathing is processed through skin.

(ii) They usually possess two pair pentadactylous limbs and have webbed feet.

(iii) Endoskeleton mostly made up of bones.

(iv) Head with a pair of nostrils ending in buccal cavity.

(c) Reptiles-

(i)The body of reptiles are hard and have continous epidermal sacles or scutes.

(ii) Their body is divided into head,neck, trunk and tail.

(iii) They possess typical cloaca

(iv) They have two pairs of pentadactyl limbs each bearing claws.

(d) Mammals-

(i)The mammals most distinctive feature is the presence of hair and fur.

(ii) They also possess special glands modified to produce milks to nurture their young known as mammary gland.

(iii) They have glandular skin with the presence of sweat glands under their skin .

(iv)They have external ears.