NCERT Book Class 12 Biology Chapter 4 Principles of Inheritance and Variation

Chapter 4 The work of Mendel and others who followed him gave us an
Principles of Inheritance idea of inheritance patterns. However the nature of those ‘factors’
and Variation which determine the phenotype was not very clear. As these
‘factors’ represent the genetic basis of inheritance, understanding
Chapter 5 the structure of genetic material and the structural basis of
Molecular Basis of Inheritance genotype and phenotype conversion became the focus of
attention in biology for the next century. The entire body of
Chapter 6 molecular biology was a consequent development with major
Evolution contributions from Watson, Crick, Nirenberg, Khorana, Kornbergs
(father and son), Benzer, Monod, Brenner, etc. A parallel problem
being tackled was the mechanism of evolution. Awareness in the
areas of molecular genetics, structural biology and bio informatics
have enriched our understanding of the molecular basis of
evolution. In this unit the structure and function of DNA and the
story and theory of evolution have been examined and explained.