Get, detailed solutions to the questions of the chapter Evolution from NCERT textbooks. The objective is to helping students regarding the pattern of answering the question as per the cbse latest marking scheme.Cbse.jagranjosh.com provided you NCERT solutions for classes 12th math and science subjects.
Some questions of this chapter are given here
Q. Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
Answer. The use of antibiotics or drugs against eukaryotic organism has resulted in the selection of resistant varieties in much lesser time. There are examples of evolution by anthropogenic action. This tells us that evolution is stochastic process which is based on chance events in nature and chance mutation in organisms. This is the antibiotic resistance which was observed in micro-organism in the light of Darwin’s selection theory.
Q. Find out from newspapers and popular science articles any new fossil discoveries or Controversies about evolution.
Answer. Dinosaurs’s fossils have revealed the evolution in Jurassic period. With this result, evolutions of many other animals have been discovered. But, recently in China two unusual fossils have unearthe which flamed the controversy over evolution of birds. Confuciusornis is one of those primitive birds that were having size of a crow and lived in China during Creataceous period.
Q. Attempt giving a clear definition of the term species
Answer. Species refers to different life forms existing on earth. Species is the lowest category into which similar organisms are grouped.
Q. Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)
Answer. In 15 million years ago or around it, primates called Rampithecus and Drypithecus were found on earth. Ramapithecus were more man like looks but Drypithecus had ape like look. In Ethopia and Tanzaniafew fossils were found which had man like bones. There revealed horminid features leading to the belief that 3-4 mya, man like primateswalked in eastern Africa. There height was about 4 ft and walked upridht. In about 2 mya Australopithcines lived in east African grasslands.They use to eat fruits and uses stones for hunting. These creatures were caleed first human. The capacity of their brain was between 650-800 cc. In year 1891, fossils discovered in Java revealed the next stage, they were named Homo erectus about 1.5 mya. Their brain capacity was about 900 cc. About 100000 – 400000 yrs back ,a man with brain size of 1400 cc lived Neanderthal man near east and central Asia. Homo sapiens aose inAfrica and moved across the continents and they developed distinct races. In around 75000-10000 yrs ago modern Homo sapiens arose.