ICAR UG & NEET UG EXAM NOTES ON BIOLOGY TOPIC ‘Origin of Life and Evolution’

ICAR UG & NEET UG EXAM NOTES ON

BIOLOGY TOPIC ‘Origin of Life and Evolution’

This exam facts are from famous book: Biology Class 11th Book by N C E R T

• Evolution deals with the origin of life.

• The universe is 20 billion years old (very old). 

• Huge clusters of galaxies comprise the universe. 

• Galaxies contain stars and clouds of gas and dust. 

• Big Bang theory attempts to explain the origin of the universe.  (ICAR UG 2012)

• Earth was formed about 4.5 billion years back. 

• There was no atmosphere on early earth. 

• Water vapour, methane, carbon dioxide and ammonia released from molten mass covered the surface. 

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• Early Greek thinkers thought the units of life is called spores (‘Panspermia’).

• According to theory of spontaneous generation, life came out of decaying and rotting matter (straw, mud). 

• Louis Pasteur demonstrated that life comes only from pre existing life. 

• Biogenesis theory did not answer how the first life form came on earth. 

• Oparin of Russia and Haldane of England gave Chemical evolution . (ICAR UG 2020)

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• In 1953, S.L. Miller (an American scientist) created similar conditions as on on earlier earth in a laboratory scale. 

• S.L. Miller created an electric discharge in a closed flask containing CH₄ , H₂ , NH₃ and H₂O (water vapour) at 800^oC. He observed formation of amino acids. (ICAR UG 2020) (ICAR UG 2019) (ICAR UG 2017)

• First cellular form of life was originated 2000 million years ago and were probably single-cells. 

• Charles Darwin did a sea voyage (tour) in a sail ship called H.M.S. Beagle round the world.

• Charles Darwin concluded that existing living forms share similarities to varying degrees not only among themselves but also with life forms that existed millions of years ago. 

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• According to Darwin, fitness refers ultimately and only to reproductive fitness. 

• Alfred Wallace was a naturalist who worked in Malay Archipelago

• Analogous organs have evolved due to convergent evolution. (ICAR UG 2021)

• Whales, bats, cheetahs and humans (all mammals) share similarities in the pattern of bones of forelimbs . (ICAR UG 2019)

• In plants, the thorn and tendrils of Bougainvillea and Cucurbita represent homology. (ICAR 2022) 

• Wings of butterflies and birds look alike and represent analogy.

• Eye of the octopus and of mammals are Examples of analogy. (ICAR 2021)

• Flippers of Penguins and Dolphins are Examples of analogy.  

• Sweet potato (root modification) and potato (stem modification) is example for analogy.

• Before industrialisation set in, there were more white-winged moths on trees than dark-winged ( melanised moths). 

• After industrialisation (in 1920), there were more dark-winged moths in the same area and proportion was reversed. 

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• Camouflage : white winged moth and dark - winged moth (melanised) on a tree trunk 

• Small black birds (called Darwin’s Finches) amazed Darwin. 

• Darwin’s finches/birds represent one of the best examples of Adaptive radiation.  (ICAR UG 2016)

• Placental mammals in Australia also exhibit adaptive radiation .

• Lamarck gave concepts of Acquired Character.

• Hugo deVries worked on evening primrose.

• Hugo deVries brought forth the idea of mutations.

• Hugo deVries believed mutation caused speciation.(ICAR UG 2018)

• Speciation causing mutation is called saltation (single step large mutation). 

• Hardy and Weinberg Principle : “Allele frequencies in a population are stable and are constant from generation to generation.“ 

• Hardy-Weinberg principle is expressed using algebraic equations. p²+2pq+q²=1

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• Genetic drift occurs if the gene frequency change occurs by chance. (ICAR UG 2017)

• 2000 million years ago (mya) the first cellular forms of life appeared on earth. 

• Coelacanth were ancestors of modern day frogs and salamanders. 

• Turtles, tortoises and crocodiles are modern day descendents of reptiles. 

• 15 mya - primates called Dryopithecus and Ramapithecus were existing. 

• Ramapithecus was more man-like. 

• Dryopithecus was more ape-like. 

• Homo habilis are first human-like being the hominid.

• Fossils of Homo erectus discovered in Java in 1891 

• Brain size of Homo erectus is 1400cc. 

Previous year questions asked from the Biology topic ‘Origin of Life and Evolution’

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