Q7 of 525 Page 233

Define the terms and given one example of each

(i) Bilateral symmetry; (ii) Coelom; (iii) Triploblastic.

(i) Bilateral symmetry: When the body is divided into identical left and right halves in only one plane, it is called bilateral symmetry. E.g., Annelida


(ii) Coelom: It is the body cavity which is filled with a fluid and is lined by mesoderm. Animals


possessing coelom are called coelomates, e.g., annelids, molluscs, arthropods, echinoderms.


(iii) Triploblastic: Animals having three germinal layers (ectoderm, mesoderm and endoderm) are called triploblastic. Example: Nematoda


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5

Identify the plant bodies, which are commonly named as “cryptogamae”. State and explain two characteristics which are exhibited by each category of these plant bodies.

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(i) Draw a neat diagram of Hydra.

(ii) Label mesoglea and gastrovascular cavity


(iii) Name the group of animals it belongs to.


(iv) Name one species of this group that lives in colonies.

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Write any three differences between Amphibia and Mammalia belonging to kingdom Animalia.

 9

Picks the odd one out and justify your choice by giving reasons.

(a) Moss, Fern, Pinus, Spirogyra.


(b) Sea cucumber, Octopus, Feather star, Star fish