The Failure of Chromosomes to Separate During Mitosis or Meiosis

Question

The failure of chromosomes to separate during mitosis or meiosis is called  
A) genetic displacement.
B) trisomy.
C) crossing over.
D) nondisjunction.
E) disjunction.

Accepted Answer

Nondisjunction is the failure of chromosomes to separate during cell division, which can result in cells with abnormal numbers of chromosomes. Trisomy, on the other hand, refers specifically to cells that have an extra copy of one chromosome, which can result from nondisjunction during meiosis. Genetic displacement and crossing over are not terms commonly used to describe this phenomenon. Disjunction simply means the separation of chromosomes during cell division and does not specifically refer to the failure of separation.