Individuals with Down syndrome have an extra chromosome 21. This is an example of which type of chromosome disorder? A. duplication B. nondisjunction C. translocation

Answer: The correct answer is A) Nondisjunction

Down syndrome is a chromosomal disorder that is also termed as Trisomy 21 that is there is an extra copy of chromosome 21.

It is caused due to meiotic non disjunction (improper separation of chromosomes) where one gamete receives one extra copy of chromosome 21 that enters in the zygote when two gametes (one from each parent) combines together making the cell trisomic that is (2n+1)

Thus, nondisjunction is the right answer.