Birds have undergone many structural adaptations or modifications to suit their aerial life. Some of these adaptations are as follows:
1.They have a Streamlined body for rapid and smooth movement.
2.Covering of body with feathers for insulation.
3.Their forelimbs are modified into wings and their hind limbs are used for walking, perching, and swimming.
4.The presence of pneumatic bones to reduce weight.
5.Presence of additional air sacs to supplement respiration
Prepare a list of some animals that are found parasitic on human beings.
Match the following:
| Column I | Column II |
| (a) Operculum | (i) Ctenophora |
| (b) Parapodia | (ii) Mollusca |
| (c) Scales | (iii) Porifera |
| (d) Comb plates | (iv) Reptilia |
| (e) Radula | (v) Annelida |
| (f) Hairs | (vi) Cyclostomata and Chondrichthyes |
| (g) Choanocytes | (vii) Mammalia |
| (h) Gill slits | (viii) Osteichthyes |
Segmentation in the body is first observed in which of the following:
(a) Platyhelminthes
(b) Aschelminthes
(c) Annelida
(d) Arthropoda
Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?