BIOLOGY X
MAR THEOPHILUS TRAINING COLLEGE, NALANCHIRA DIGITAL TEXTBOOK BIOLOGY- X ANCY J DAS BED NATURAL SCIENCE REG NO : 18121302002
Dear students You will be curious to know how we evolved from our and sisters through the windows of knowledge. You will certainly be surprised to learn how different experiments and milestones of evolution act that leads to the formation of present human beings. The recent developments in the field of evolution which leads to the progress in human life. The chemical evolution of life and importance ancestors of human beings which generate scientific attitude and curiosity among the students. This test deals with the important milestones of evolution. Digital books provide students with a complete and rich learning experience and help them improve their academic performance. I hope that this would help you to understand and create new knowledge about evolution. Love and regards, ANCY J DAS
Learning Outcome The learner, ������Understand about the concept of evolution. ������Analyze the important milestones of phylogeny. ������Understand about the different experiments. ������Develop scientific literacy and attitude. ������Aware about the human ancestors. ������Get to know about different theories of evolution.
CONTENT THE MILE STONES OF EVOLUTION CHAPTERS 1. CHEMICAL EVOLUTION THEORY 2. UREY-MILLER EXPERIMENT. 3. GEOLOGICAL TIME SCALE 4. EVOLUTION OF HUMAN BEINGS
THE MILE STONES OF EVOLUTION
1 CHEMICAL EVOLUTION THEORY
CHEMICAL EVOLUTION THEORY How might have life originated? Is it linked to earth’s origin? Is there life on other planets as well? All such questions have always come under the purview of scientific enquiry. Scientist has been able to put forth certain hypothesis on how earth and life on earth originated. The more predominant Theory on the origin of life on earth that was formed about 4500 million years ago, is the chemical evolution theory. The Panspermia hypothesis is also a widely discussed one. The panspermia hypothesis suggest life began on earth when the ‘seeds’ of life, already present in the universe, arrived here from space from comets and meteors.
The hypothesis that evolved into the theory of chemical evolution is that life originated as a result of the changes that occurred in the chemical substances in seawater, under specific conditions in primitive earth. This theory is generally accepted by the scientific world due to its experimental evidences. The Russian scientist AI Apparent (1924) and the British scientist. J.B.S. Haldane (1929) are the proponents of this theory.
Analyse illustration 1.1 and prepare a note on the theory of chemical evolution in your science diary.
Indicators ������Atmosphere of primitive earth- Peculiarities ������Sources of energy ������Formation of ocean ������Chemical reactions that lead to the formation of cell. The scientific bias of this hypothesis regarding the origin of life was later proved through various experiments. For more information- https://www.youtube.com/watch? v=mRzxTzKIsp8
2 UREY-MILLER EXPERIMENT
UREY-MILLER EXPERIMENT Stanley L. Muller and Harold C. Urey Performed an experiment to describe the origin of life on earth. They were of the idea that the early year atmosphere was able to produce amino acids from inorganic matter. The two biologist made use of methane, water, hydrogen and Ammonia which they considered were found in the early earth’s atmosphere. Analyse illustration 1.2 and the description on the basis of the given indicators and prepare a note in your science diary.
The Experiment ������The chemicals were sealed inside sterile glass tubes and flasks connected together in a loop and circulated inside the apparatus. ������One flask is half-filled with water and the other flask contains a pair of electrodes.
������The water vapour was heated and the vapour released was added to the chemical mixture. The released gases circulated around the apparatus imitating the earth’s atmosphere. ������The water in the flask represents the water on the earth’s surface and the water vapour is just like the water evaporating from lakes, and seas. The electrodes were used to spark the fire to imitate lightning and storm through water vapour. ������The vapours were cooled and the water condensed. The condensed water trickles back into the first water flask in a continuous cycle.
������Miller and Urey examined the cooled water after a week and observed that 10- 15% of the carbon was in the form of organic compounds. ������2% of the carbon had formed 13 amino acids. Indicators ������Atmosphere of primitive earth and chemical components in the glass flask. ������Organic molecules formed after the chemical reaction.
In the Oceans of primitive earth, organic compounds were formed due to chemical evolution that continued for millions of years. A video link showing the details of the experiment is given below. https://www.youtube.com/watch? v=NNijmxsKGbc
3 GEOLOGICAL TIME SCALE
GEOLOGICAL TIME SCALE Researches all over the world are still striving to unravel the mysterious related to the origin of life on earth. Analyse the major events related to the origin of life as illustrated in the geological time scale 1.3.
Indicators ������Primitive cell ������Origin of Prokaryotes ������Origin of Eukaryotes ������Appearance of multicellular organisms Presence of life on other planet is also a main area of research. Life emerged as a result of the accidental combining of inorganic molecules. Many space explorations still undertake the quest to find out whether similar phenomenon occur anywhere else among the millions of celestial orbs.
4 EVOLUTION OF HUMAN BEINGS
EVOLUTION OF HUMAN BEINGS
Fossils were discovered from Africa
Fossils were discovered from Africa.
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