Ex.11. Do you know that a frog is often used for biological experiments? Scientists began to examine them so long ago so they can be called the most ancient animals for laboratory use. As a rule, poisons were tested on frogs and even now, how they respond to medicines is of much interest for researchers. 20,000 amphibians were used in the UK in 2004. They are vertebrates with simple morphology. Do you know its morphology? Have a look!
