Test: Origin & Evolution - 1 - UPSC MCQ

The doctrine of spontaneous generation was coherently synthesized by Aristotle, who compiled and expanded the work of earlier natural philosophers and the various ancient explanations for the appearance of organisms, and was taken as scientific fact for two millennia.

By 1860, the debate had become so heated that the Paris Academy of Science offered a prize for any experiments that would help resolve this conflict. Louis Pasteur, has published the results of an experiment he did to disproved spontaneous generation in these microscopic organisms.

Sterilization is the killing or removal of all microorganisms, including bacterial spores, which are highly resistant. It was carried by L. Pasteur.

Theory of special creation of origin of life:- 
This theory in biology was proposed by Spanish monk father Sudrez. According to this oldest theory, all the different forms of life that occur today on planet earth, have been created God, the Almighty or some supernatural power.

Earth formed around 4.6 billion years ago, approximately one - third the age of the universe, by accretion from the solar nebula.

Modern Theory or Oparin-Haldane Theory of Origin of Life:

According to this theory life originated on early earth through physico-chemical pro­cesses of atoms combining to form molecules, molecules in turn reacting to produce inor­ganic and organic compounds. Organic compounds interacted to produce all types of macromolecules which organised to form the first living system or cells.

According to Oparin, the atmosphere of primitive earth was reducing because the hydrogen atoms were most numerous and most reactive. Large quantities of hydrogen gas, nitrogen gas, carbon dioxide, methane, water vapour, ammonia were present but free oxygen was not present in significant amount. Hence, oxygen was absent during the formation of earth.

J. B. S  Haldane worked on the origin of life and finally settled in India. J. B. S Haldane was a British scientist, well known for his works in physiology, genetics and mathematics.

The giant nucleoprotein molecules were formed by the union of nucleic acid and protein molecules. These nucleoprotein particles were described as free living genes. Nucleoproteins gave most probably the first sign of life.

Moon is a natural satellite of earth but life on the moon is not possible as on the earth because of many reasons. Firstly, there is no water on the moon, which is the first and foremost requirement for the life. Life first started on the earth because of water and if no water we can imagine no life.

Homology refers to similar structures with dissimilar functions, but with similar origin and architecture.
Example of homologous organs are :
Forelimbs.
Brains.
Heart.

 Nails of humans and claws of cat: These are homologous organs as they have similar structure but perform different function.

Divergent evolution is the process whereby groups from the same common ancestor evolve and accumulate differences, resulting in the formation of new species.

Divergent evolution may occur as a response to changes in abiotic factors, such as a change in environmental conditions, or when a new niche becomes available. Alternatively, divergent evolution may take place in response to changes in biotic factors, such as increased or decreased pressure from competition or predation.

Wings of butterfly and wings of a bird , they both are analogus organs . Wings of butterfly does not have hollow bones wheres birds have hollow bones attached to its feathers and they are used from protecting it from cold also. 

The living animals which possess some characters of two different groups of animals are called connecting link. Peripatus is a primitive arthropod having joined paired legs, compound eyes and tracheas like other arthropods but also displays certain annelidan charachtersticks, such as worm - like segmented body. 

Proterospongia is considered as a connecting link between protozoa and the porifera because it has both protozoan and poriferan characters like it is a colonial protozoan and its cells are similar to collar cells of sponges.

"Ontogeny recapitulates phylogeny" is a catchy phrase coined by Ernst Haeckel, a 19th century German biologist and philosopher to mean that the development of an organism (ontogeny) expresses all the intermediate forms of its ancestors throughout evolution (phylogeny). His theory was later proved wrong, but the catch phrase remains.

The study of human evolution involves several scientific disciplines, including physical anthropology, primatology, archaeology, paleontology, neurobiology, ethology, linguistics, evolutionarypsychology, embryology and genetics.

Humans first evolved in Africa, and much of human evolution occurred on that continent. The fossils of early humans who lived between 6 and 2 million years ago come entirely from Africa.

The clear advantage of bipedalism was the possibility for ancient hominin species to use their hands. With the evolution of bipedalism, this special advantage was evolved only by the primates. This advantage offered a benefit that overcame the fatal disadvantage of slow speed.