The picture given above shows three different mammals. Identify the animals and write their scientific names and one characteristic feature of each of them, which the other two do not possess.

Mammals and birds (Aves) are vertebrates and homoiotherms. They show double circulation, but, differ in many other aspects.
(a) Write any two adaptations/modifications, a bird has, for its aerial mode of life.
(b) Bring out any four differences between Aves and mammals.

Observe the picture showing some vertebrates and answer the following questions.
(i) Identify the animal(s) with
(a) two-chambered heart
(b) three-chambered heart
(c) four-chambered heart
(ii) Which among them show(s) external fertilisation?

Study the two animals (fishes), A and B in the picture given above and answer the following questions.
(a) Identify the class, which each of them belongs to.
(b) Write four differences between the two

Phylum Chordata includes animals which characteristically possess a notochord either throughout life or during early embryonic life.
(a) Give an example of a sub-phylum and an animal, where the notochord
(i) extends from head to tail and is persistent throughout life.
(ii) is present only in the tail region of the larval stage.
(b) What happens to it in the sub-phylum, which reptiles belong to?

Kamal, a student of class IX has brought a crab and an apple snail from the beach. He has identified them both as members of Phylum Mollusca, as they have a shell. As a senior student of biology, help him to identify the animals correctly.
(a) Name the phylum, crab belongs to and that which apple snail belongs to.
(b) Write any four differences between the animals of the two phyla.

Two animals of Phylum Annelida are shown in the picture given below. Observe them and answer the questions that follow:

(a) Identify and write the scientific names of the animals A and B.
(b) Write two major differences between them.

(a) Identify the structure given above and name the phylum, it is characteristically present in.
(b) Where is it generally present in the body of the animals?
(c) Name the cell it contains.
(d) Mention two of its functions.

The diagram given above shows the arrangement of germinal layers.
(i) Identify the parts labelled A, B, C and D.
(ii) What technical term is given to animals with pattern (a) and (b), respectively?

Animals of the phyla like Annelida, Arthropoda, Mollusca, Chordata, etc. have organ system level of organisation. Organ systems in different groups/phyla of animals exhibit various patterns of complexities.
Name and describe the two types of circulatory system among animals and name one phylum as example for each.

Animals are classified on the basis of their symmetry into three categories.
(i) Asymmetrical,
(ii) Radially symmetrical and
(iii) Bilaterally symmetrical.
They are also classified into diploblastic and triploblastic.
(a) Name one phylum and an animal as example for each of the following, where animals are
(i) diploblastic and radially symmetrical.
(ii) triploblastic and radially symmetrical.
(b) Name two phyla, where animals are exclusively marine.