What describes the two identical halves of a single replicated chromosome joined at the centromere?

• A. Chromatids
• B. Chromosome
• C. Homologous chromosomes
• D. Pedigree chart

Answer: (A)

When a chromosome is replicated, it is copied so there are two identical DNA strands that stay attached to each other at the centromere. Those two identical copies are called sister chromatids. They form the two halves of a single replicated chromosome, together composing one continuous chromosome unit until they separate during cell division. So describing the two identical halves that remain joined at the centromere as chromatids is exactly right. The term chromosome can refer to the whole structure or to a single chromatid after separation, not specifically the two attached halves. Homologous chromosomes are matching pairs from each parent, not the two halves of one replicated chromosome, and a pedigree chart is just a family-tree diagram.