Explanation

In trisomic condition, diploid organism have extra chromosome represented by the chromosomal formula2n + 1 . One of the pairs of chromosomes has an extra member, so that a trivalent may be formed during meiotic prophase, e.g., Down’s syndrome (45+XX or 45+XY), Klinefelter’s syndrome (44 + XXY). In monosomic, diploid organism has one chromosome of a single pair missing with genomic formula 2n − 1. Monosomics can from two kind of gametes, (n) and (n-1), e.g., Turner’s syndrome (44 + X).