Principles of inheritance and variation, Monohybrid cross, Test cross

The document discusses genetics and the principles of inheritance and variation. It describes the work of James Watson and Francis Crick in discovering the structure of DNA. It then discusses Gregor Mendel's experiments with pea plants in the 1850s-1860s, which led him to propose his laws of inheritance. Mendel found that when he crossed true-breeding pea plants with contrasting traits, the offspring (F1 generation) always resembled one parent, but in the next generation (F2) both traits reappeared in a 3:1 ratio.