Group B chromosomes, also known as supernumerary chromosomes, refer to additional or extra chromosomes that are present in certain species. These chromosomes are separate from the standard set of chromosomes found in individuals, known as autosomal chromosomes. Group B chromosomes have been identified in various organisms, such as plants, animals, and fungi. They are characterized by their unique features and composition, distinct from the main chromosomal complement. The presence of these additional chromosomes can have different effects, ranging from no apparent influence to important implications in fertility, sex determination, or genetic variability. Group B chromosomes are a fascinating subject of study, shedding light on the complexity and diversity of chromosomal structure in different species.