Rajasthan Board RBSE Class 10 Science Notes Chapter 16 Universe and Organic Evolution
- We are able to see infinitely large number of stars, some planets and other objects. The whole group of these bodies is called the Universe.
- The science which deals with the study of universe is called cosmology.
- Swami Vivekanand had aptly explained the knowledge in the Vedas by saying that conscious divided into many from a unit and made the universe. Numerous kinds of animals and plants which we see in this world are different form of that consciousness. This thought of a single form is called ‘Adwaita’.
Theory of Biocentrism :
Robert Lanza worked with Bob Berman and proposed the Theory of Biocentrism in 2007. As per this theory, the universe came into existence because of life. In other words, the universe was created so that life could be created and evolved.
Big Bang Theory:
The Big Bang Theory is the most accepted theory of origin of universe.
- As per this theory, the universe came into existence as a result of a big explosion which happened 13.8 billion years ago in a highly dense and extremely hot object. The way shards and pieces fly away after an explosion, the components of the universe are still flying away from each other.
- When the universe cooled down after the explosion then subatomic particles came into existence. Later on, the subatomic particles coalesced to form simple atoms. The atoms formed giant clouds of initial elements; like hydrogen, helium and lithium. Those clouds condensed due to gravitation and gave birth to stars and galaxies. The lighter elements formed heavier elements in due course of time and finally formed stars and supernovas.
Paul Steinhardt of Princeton University has proposed Ekpyrotic Model and has said that that the universe came into existence as a result of collision of two three-dimensional universes in fourth dimension.
Physical Theories for Origin of Life
- In 1924, Russian scientist Alexander Oparin proposed the theory of creation of life from inanimate objects.
- In 1929, J. D. S. Haldane expanded the scope of Oparin’s theory. Haldane proposed that when the earth gradually cooled down after separating from the sun then many elements were formed on earth. Heavier elements sank in the centre of earth and lighter elements (hydrogen, nitrogen, oxygen and argon) made the primitive atmosphere of the earth.
- These elements combined to form ammonia and oxygen. As all of the oxygen was consumed in this process, the atmosphere became reducing in nature. Effects of sunlight and lightning ensured that chemical reactions kept on happening and it led to formation of various compounds; like amino acid, sugar, glycerol, etc. in due course of time. When these compounds dissolved in water then Primordial Soup was formed on the earth.
- Miller’s Experiment: Miller set up an apparatus to prepare organic compounds. The apparatus contained a round bottom flask, a electric discharge bulb, and a condenser. The round bottom flask was filled with water and air was sucked out of it. It was followed by filling the flask with methane, ammonia and hydrogen in 2:1:2 ratio.
- When water started to boil due to electric discharge then the resultant vapour facilitated movement of gases in circular fashion. The vapour was analysed after condensation. His analysis revealed presence of various organic compounds like amino acid, acetic acid, etc. experiment proved that organic compounds which are fundamental to life have been made from inorganic substances. This experiment is famously known as Miller-Urey Experiment.
Spiritual Theories for Origin of Life:
- The modem life form is fully based on DNA. The information stored in DNA is carried from nucleus to cytoplasm by RNA. Ribosomes, in cytoplasm, make proteins (enzymes) as per the message from DNA. Catalysis by protein controls all the biological processes.
- Life on earth coming from another celestial body is also a well accepted concept among some sections of the scientific community. They believe that life did not originate on earth rather came from some celestial body in the form of microspores.
Remains of ancient species are called fossil. Some living beings got buried under soil and other substances and were transformed into fossils.
- Charles Darwin explained the evolution of species on the basis of natural selection.
- Darwin proposed that each species produces its progenies in large numbers. But no two individuals are same.
- A large number of individuals results in intense competition for various resources like food, shelter, air, etc.
- The nature selects only the fittest, i.e. the concept of survival of the fittest holds true.
- The fittest is able to produce progenies in even larger number and it eventually results in origin of a new species.
- Hugo De Vries proposed that sudden changes in individuals results in origin of a new species. De Vries termed such changes as ‘mutation’.
Each species of the modern world has evolved from previous specie through changes at different stages. Thus, each species has its own evolutionary history. The evolutionary history of a particular species is called phylogeny of that species.