alleryStart learning →Nondisjunction is best described as which failure?
AChromosomes failing to replicate before division
BChromosomes or chromatids failing to separate
CChromosomes failing to condense during prophase
DChromosomes failing to pair with their homologue
Answer & Solution
Correct answer: B. Chromosomes or chromatids failing to separate
1. Disorders of chromosome number arise when the wrong number of chromosomes reaches a gamete.
2. Nondisjunction occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis.
3. Some gametes therefore end up with an extra chromosome and others with one too few.
4. Failure to condense or replicate would disrupt division in other ways, but neither is what nondisjunction means.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 13 "Modern Understandings of Inheritance", section 13.2 Chromosomal Basis of Inherited Disorders_
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