How are pteridophytes different from the phanerogams?

List three groups of plants. Which plants are referred to as vascular plants? Out of these which group is further classified on the basis of number of cotyledon? State its two characteristics.

How would you choose between two characteristics to be used for developing a hierarchy in classification?

Explain how animals in Vertebrata are classified into further subgroups?

(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.