List three factors that provide evidences in favour of evolution in organisms and state the role of each in brief.

Explanation

(i) Homologous organs: Forelimb of human and bird are homologous organs. They have same structural design and developmental origin but they have different functions and appearance. Homologous organs help us to understand that the organism have evolved from a common ancestor. The more common characteristics the two species have the more closely they are related.
(ii) Analogous organs : Analogous organs are those organs which have different basic structural design and development origin but have similar appearance and perform similar functions.
Example : The wings of birds and bats look similar but have different design in their structure. They have a common function of flying but their origins are not common. So, birds and bats are not closely related.
(iii) Fossils and their study is useful in knowing about the species which are no longer alive. They provide evidence and missing links between two classes. They are helpful in forming a sequence of organısms in the pathway of evolution.
Thus, fossils have an importance in deciding evolutionary relationship. Archaeopteryx is a fossil bird. It had feathers, fused bones and beak which are exclusively bırd structures. It also had some features which are found in reptiles e.g., teeth in jaw, claws on free fingers and a long tail. This fossil provides a clue that birds have evolved from reptiles.