Answer:
Trisomy 21 would show presence of an extra copy of chromosome 21 in a karyotype
Explanation:
Humans are diploid organisms, having 23 pairs of chromosomes (46 chromosomes in each cell. Trisomy represents a chromosomal disorder, with presence of an additional chromosome (total 47 chromosomes, instead of 46).
Down syndrome is a genetic disorder caused by trisomy of chromosome 21. Karyotype is used to represent appearance and number of chromosomes present in nucleus of a cell.
Thus, in karyotype trisomy 21 there would be an additional copy of chromosome 21. Diagram of karyotype trisomy 21 is attached with answer.
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell.