Question

The condition of an extra chromosome in addition to its homologous pair is

• A. Trisomy
• B. Monosomy
• C. Polyploidy
• D. Nullisomy

Answer 1

The correct option is A Trisomy

• A trisomy is a chromosomal disorder characterised by an additional chromosome, so the person has 47 instead of 46. Down syndrome, Edward syndrome and Patau syndrome are the most common forms of trisomy.
• Monosomy is a form of aneuploidy with the presence of only one chromosome from a pair.
  
• Polyploidy is the state of a cell or organism having more than two paired (homologous) sets of chromosomes.
• Nullisomic is a genetic condition involving the lack of both the normal chromosomal pairs for a species (2n-2).

So, the correct answer is 'Trisomy'.