The following points highlight the four theories proposed for the mechanism of crossing over. The theories are: 1. Janssen's Classical Theory 2. Belling's Copy Choice Theory 3. Uhl's Theory 4. Darlington's Theory of Crossing Over. Theory # 1. Janssen's Classical Theory: Janssen (1909) believed that prior to the formation of chiasmata the homologous maternal and paternal chromosomes come in pair [...]
The following points highlight the top two theories explaining the causes of evolution. The theories are: 1. Lamarckism or Theory of Inheritance of Acquired Characters 2. Evolutionary by Natural Selection (Darwinism). Theory # 1. Lamarckism or Theory of Inheritance of Acquired Characters: Jean Baptiste Lamarck (1744 - 1829), a French biologist formulated the first theory of evolution (Fig. 27. 10). [...]
The following points highlight the top five theories of the evolution of organic forms. The theories are: 1. Theory of Eternity of Present Conditions 2. Theory of Special Creation or Creationism 3. Cosmozoic Theory 4. Theory of Catastrophism and Spontaneous Creation 5. Theory of Organic Evolution. Theories of the Evolution of Organic Forms: Theory of Eternity of Present Conditions Theory [...]