The process of change of simpler organisms into complex living organisms due to the gradual changes is called organic evolution. This is almost universally accepted that the present day organisms are evolved by progressive development of simpler organisms to the complex organisms by gradual modifications with time. Life began on the earth after the solidification from molten form and had sufficiently cooled down. During the course of evolution simple form changed into complex form, unicellular forms changed into colonial forms and than multi cellular forms of different tissues. The development of sexuality and alternation of diploid as well as haploid stages of life cycle started. Reduction of haploid gametophytic phase in the life cycle take place. Evolution of new group of plants and animals advances very slowly and it requires millions of years to produced new plants and animals. Evolution proceeds either on progressive or on retrogressive lines, both of these processes of evolution are proceeding simultaneously in nature.
First living organism :
1. They were heterotrophic nature.
2.They were prokaryotic like bacteria and were single celled.
3. They were anaerobic in nature.
4. DNA was naked i.e lacks histone protein.
5. Enzymes were present.
6. Soup like sea water was the source of chemoheterotrophic nutrition.
7. The atmosphere was reducing.
8. The respiration was anaerobic and carbon dioxide was evolved.
No comments:
Post a Comment