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A person with a genetic composition AA+XYY composition. The non-disjunction is in the __________ parent and in _____________ meiotic division.(a) Male, 1st(b) Male, 2nd(c) Female, 1st(d) Female, 2ndThis question was posed to me in a national level competition.This intriguing question comes from Sex Determination in Mammals topic in division Chromosomes and Sex Determination of Cytogenetics

Answer»

Right choice is (b) Male, 2ND

The explanation is: A female can never have Y chromosome to start with so the non-disjunction is in a male. If the non-disjunction was in 1st DIVISION improper segregation of X and Y will produce XY gamete. Here there is an improper 2nd division where 2Y generated in meiosis 2 moves to same POLE giving YY gamete.



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