Question

Presence of gills in tadpole of frog indicates that
A. Frog will have gills in future
B. Frog evolved from gilled ancestors.
C. Fishes were amphibians in the past
D. Fishes evolved from frog-like ancestors.

Answer 1

Hint: Frogs come under Phylum chordata and class Amphibians. Frogs are amphibians because they live in water as a tadpole and on land when they become adults. Tadpole has a special organ to breathe in water which are gills and respires through lungs on land when adult.

Complete answer:
1.It is known that amphibians (frogs) have originated from fishes. Resemblance of amphibians (frogs) can be observed in most of the body systems .
2.Both frogs and fishes have spinal cord and backbone. They both have bilateral symmetry.
3.Both are exothermic, or cold-blooded. This means that they cannot maintain their body temperature by internal means.
4.Generally, amphibians like frogs live both on land as well as in water, and fish live in water.

5.However, some fishes can survive on land, and some frogs can only live in water. Example- The climbing perch (Anabas testudineus) is a fish that can breath air and crawl along land for short distances. And the African dwarf frog usually spends its entire life living underwater. So both groups have habitats which overlapped.
6.Both of them usually lay eggs in water. But there are some exceptions to it too. Some fish, such as guppies and certain sharks give live birth instead of laying eggs. And some toads, which are close relatives of frogs, give live birth as well. So mostly frogs and fishes lay eggs in water, but a few give live birth instead.

Hence, the correct answer is option (C)

Note: 1.A frog differs from a toad in the absence of warts.
2.Male frog has capability to crock louder than female with the help of vocal sacs
3.A frog has ears but no pinnae.
4.A frog has four fingers on its hands, and five toes on its legs.