Changes in Chromosome Number are Usually the Result Of

Question

Changes in chromosome number are usually the result of  
A) genetic displacement.
B) trisomy.
C) crossing over.
D) nondisjunction.
E) disjunction.

Accepted Answer

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to changes in chromosome number. This can result in either an extra chromosome (trisomy) or a missing chromosome (monosomy) in the resulting cells.