Which of the following describes an individual with trisomy?

An individual with trisomy has an extra chromosome in addition to the typical diploid set. In a normal diploid organism, the chromosome number is designated as 2n, where "n" represents the number of pairs of chromosomes. When an individual has trisomy, one specific chromosome pair has an extra chromosome; thus, instead of having the standard number of chromosomes (2n), the individual has one extra, resulting in a total chromosome count of 2n + 1.

For instance, in humans, the typical diploid number is 46 chromosomes (23 pairs), so in the case of trisomy, there would be 47 chromosomes (46 + 1). This is commonly seen in conditions such as Down syndrome (trisomy 21), where there are three copies of chromosome 21 instead of two. Hence, the choice indicating 2n + 1 accurately reflects the genetic makeup of an individual with trisomy.

While other options describe different chromosomal arrangements, they do not accurately represent the condition of trisomy. The designation 2n - 1 refers to a situation where there is a missing chromosome (monosomy), 2n correctly reflects a diploid state without any abnormalities, and 3n