Final answer:
In the list, 'triploid' is least related as it refers to having three complete sets of chromosomes, unlike 'trisomic,' 'monosomic,' and 'aneuploid' which are all types of aneuploidy involving an abnormal number of individual chromosomes.
Step-by-step explanation:
In the list provided, the term triploid is the least related to the others. Terms such as trisomic, monosomic, and aneuploid all refer to types of aneuploidy, which is a condition characterized by an abnormal number of chromosomes. Trisomy and monosomy are types of aneuploidy, where an individual has an extra or missing chromosome, respectively. On the other hand, triploid describes a condition where an organism has three complete sets of chromosomes rather than the usual two (diploid) for that species, which is a different type of chromosomal aberration than aneuploidy.
Monosomic individuals are typically non-viable as they are lacking essential genes, while trisomic individuals may survive but suffer from genetic imbalances such as Down syndrome, which is caused by an extra copy of chromosome 21. Aneuploidy results from errors like nondisjunction, which can lead to gametes with an incorrect number of chromosomes and subsequent developmental issues in the zygote formed from such gametes.