1Into how many classes are vertebrates divided on the basis of physical structure and development? Name them.
2Write any six characteristics of the class Pisces.
3A sea horse does not look like an ordinary fish. Why is it still placed in Pisces?
4Why is a frog called an amphibian?
5Write the characteristics of the class Amphibia.
6Write any four differences between Pisces and Amphibia.
7What is the difference between external and internal fertilization? Give examples from fish.
8Why must a frog's skin always stay moist?
9Why do amphibians need water for reproduction?
10How do a fish's streamlined body and fins help it live in water?