Which term refers to the number of copies of each chromosome found in a cell?

The term that refers to the number of copies of each chromosome found in a cell is "ploidy." In genetics, ploidy indicates the total number of sets of chromosomes present. For example, a diploid organism has two copies of each chromosome (one set from each parent), whereas a haploid organism has only one set of chromosomes.

Understanding ploidy is essential because it plays a crucial role in processes such as meiosis and fertilization, influencing inheritance patterns and genetic variation. In contrast, the other terms do not pertain specifically to the number of chromosome copies. The centromere is the region where sister chromatids are joined, chromatid refers to one half of a duplicated chromosome, and alleles are different forms of a gene that can exist at a particular locus.