Statement I: | The name cnidaria is derived from the cnidoblasts or cnidocytes that are collared flagellated cells involved in water transport through the body of Cnidarians. |
Statement II: | Polyps are free swimming Cnidarians and Medusae are sessile Cnidarians. |
I: | are commonly known as sea walnuts or comb jellies |
II: | are exclusively marine, radially symmetrical, diploblastic organisms with tissue level of organisation |
III: | use cilia for locomotion |
IV: | reproduce only by sexual means |
1. | statocysts | 2. | osphradia |
3. | flame cells | 4. | antennal glands |
I: | They exhibit organ-system level of body organisation and bilateral symmetry. |
II: | They are triploblastic, metamerically segmented and coelomate animals. |
III: | They possess only longitudinal muscles in their body wall which help in locomotion. |
IV: | A closed circulatory system is present. |
I: | Body of arthropods is covered by chitinous exoskeleton. |
II: | They have jointed appendages (arthros-joint, poda-appendages). |
III: | Circulatory system is of open type. |
IV: | Excretion takes place through malpighian tubules in insects. |
V: | They are mostly dioecious and fertilisation is usually internal. |
VI: | They are mostly oviparous. |
1. | Annelids | 2. | Mollusca |
3. | Round worms | 4. | Arthropods |
I: | They are bilaterally symmetrical, triploblastic and coelomate animals. |
II: | Body is covered by a calcareous shell and is segmented with a distinct head, muscular foot and visceral hump as metameres. |
III: | A soft and spongy layer of skin forms a mantle over the visceral hump. |
IV: | They are usually dioecious and oviparous with indirect development. |
Assertion (A): | Hemichordata was earlier considered as a sub-phylum under phylum Chordata but now it is placed as a separate phylum under non-chordata. |
Reason (R): | Hemichordates have a rudimentary structure in the collar region called stomochord, a structure analogous to notochord. |
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. |
I: | the presence of a notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits. |
II: | bilateral symmetry, triploblastic body organisation, true coelom with organ-system level of organisation. |
III: | a post anal tail and a closed circulatory system. |
Statement I: | Protochordates are exclusively marine. |
Statement II: | In Urochordata, notochord is present only in larval tail, while in Cephalochordata, it extends from head to tail region and is persistent throughout their life. |