Trisomy is a mutation that results in a cell having an extraA) nitrogen base. B) codon. C) chromosome. D) gene.

If you break down the word trisomy, tri refers to three
and somy refers to chromosomes. Since chromsomes occur in pairs, trisomy indicates an
additional chromosome at a certain position on a karyotype. Therefore, the answer is
chromosome. A trisomy can result during gamete formation. If non-disjunction occurs
during meiotic division, then, a gamete may have one more or one less chromosome in it.
If the gamete with an extra chromosome goes on to form a zygote, the zygote will contain
an additional chromosome at that location. This is a form of aneuploidy which is an
abnormal set of chromosomes.