The significance of the chromosomal theory in genetics lies in its assertion that genes are located on chromosomes, providing a tangible framework for understanding inheritance. Proposed in the early 20th century, this theory links the behavior of chromosomes during meiosis with Mendelian inheritance patterns. It has profound implications for studying genetic variation, evolution, and trait expression. Understanding chromosomal theory is essential for modern genetics, enabling advancements in fields such as genetic engineering, genomics, and molecular biology, and contributing to medical research and biotechnology.