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NEETZoologyPrinciples of Inheritance and Variation

What causes chromosomal disorders?

Options

  1. AGenetic mutations in a single gene
  2. BAbsence, excess, or abnormal arrangement of chromosomes
  3. CDefective protein synthesis
  4. DViral infections

Correct answer

B. Absence, excess, or abnormal arrangement of chromosomes

Step-by-step solution

The chromosomal disorders on the other hand are caused due to absence or excess or abnormal arrangement of one or more chromosomes . Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy. For example, Down’s syndrome results in the gain of extra copy of chromosome 21. Similarly, Turner’s syndrome results due to loss of an X chromosome in human females. Failure of cytokinesis after telophase stage of cell division results in an increase in a

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