Final answer:
The chromosome on the bottom, compared to the one on top, is described as an acentric fragment because it lacks a centromere. Terms like dicentric, holocentric, and pseudocentric refer to different centromere configurations. Acentric fragments cannot function normally during cell division due to the absence of a centromere.
Step-by-step explanation:
Compared to the chromosome on top, the one on the bottom is best described as a acentric fragment. An acentric chromosome fragment lacks a centromere, which is essential for the chromosome's movement and segregation during cell division. In contrast, some other terms used to describe chromosomes or fragments based on their centromere characteristics are: dicentric (two centromeres), holocentric (centromere activity spread along the entire chromosome), and pseudocentric (which appears to have a centromere but does not function as one).
Chromosomes are identified by their size, number, and centromere position, among other characteristics. The centromere is where the sister chromatids are most closely connected, and each chromosome arm is designated as a short arm (p) and long arm (q). Since an acentric fragment lacks this critical structure, it does not behave normally during cell processes such as mitosis or meiosis.