Two-chambered heart occurs in

Sehai and Sidak observed an animal in their garden. Sehai called it an insect while Sidak said it was an earthworm. Choose the character from the following which confirms that it is an insect.

Write appropriate terms for the following:
$(i)$ Animals that are able to maintain a constant body temperature over a wide range of environmental temperatures.
$(ii)$ Animals which have a pseudocoelom.
$(iii)$ Plants which bear naked seeds.

Name two mammals which lay eggs. Between which two phyla do they serve as connecting link? Name a mammal which gives birth to poorly developed young ones.

Identify the phylum of kingdom Animalia in which the animal has:
$(a)$ $A$ pseudocoelom
$(b)$ $A$ water-driven tube system
$(c)$ Jointed legs
$(d)$ Pores in the body leading to a canal system
$(e)$ Notochord at some stages of their life.

Which of the following is not a characteristic feature of Protochordata?