Question

explain with an example for each how the following provide evidence in favour of evolution in organisms

Answer 1

a) Fossils: Organisms which form connecting links can be fossils of extinct species. Connecting links act as intermediary or transitional forms between the lower species and the higher species. They depict evolution.
*Green protozoan such as euglena serve as connecting links between the animal and the plant kingdom. Euglena has both animal characters like pellicle and flagellum and plant characters like chloroplasts and paramylum bodies.
*Archaeopteryx is a fossil whcih acts as a connecting link between reptiles and birds. It is a primitive bird from the Jurassic period. Archaeopteryx had bird-like characters such as wings, feathers and a beak. It also had reptilian characters such as a long tail, a toothed beak and clawed digits on the wings.
b) Phylogeny: Phylogeny is the evolutionary history of a species from its ancestors. A comparative study of the ontogeny of different forms of animals helps in knowing about their phylogenetic relationships which confirm evolution. Homologous structures which have a common ancestor intheir origin serve as an evidence of evolution. Analogous structures though they are not from a common ancestor, they have their function in common.