In this section each item consists of six sentences of a passage. The first and the sixth sentences are given in the beginning as S1 and S6. The middle four sentences in each have been jumbled up and labelled as P, Q, R and S. You are required to find out the proper sequence of the four sentences and mark your response accordingly on Answer Sheet. S1 : Biology is the youngest of the formalized disciplines of natural science. S6 : Life expectancy of human beings has dramatically changed over the years. P : However, the twentieth century and certainly the twenty-first century has demonstrated the utility of biological knowledge in furthering human welfare, be it in health sector or agriculture. Q : The discovery of antibiotics, and synthetic plant-derived drugs, anaesthetics have changed medical practice on one hand and human health on the other hand. R : Applications of physics and chemistry in our daily life also have a higher visibility than those of biology. S : Progress in physics and chemistry proceeded much faster than in biology. The correct sequence should be