KCET 2014 Biology Solved Paper

An aneuploidy organism or cell is the one having a chromosome number that is not an exact multiple of the monoploid (n) with one genome. A trisomy is a condition in which an individual has inherited an extra chromosome, resulting in three copies of a particular chromosome instead of the usual two copies. Therefore, the individual would have 47 instead of 46 chromosomes. The presence of an extra copy of chromosome 21 leads to Down syndrome.