Gain or loss of a chromosome caused by failure of chromatids to segregate is called

1. During cell division the chromatids normally separate evenly. 2. Failure of that segregation leaves one cell with an extra chromosome and one short. 3. This gain or loss of chromosomes is called aneuploidy. 4. Polyploidy is the gain of a whole extra set, which is a different thing. _Source: syllabus Biology Ch4 'Principles of Inheritance and Variation'_