<prompt> Chromosome 21 is -MetacentricSubmetacentricAcrocentricNone  <response>: Ans. is c i.e., Acrocentrico Each chromosome has two armsi p arm the shorter of twoii q arm longer oneo Depending on the position of there junction centromere they can be classified into :1. Metacentric The centromere is in the middle so that the two arms of chromosomes are almost equal. These chromosomes are : chromosomes 1,2, 3 and X-chromosome.2. Submetacentric p arm is short and q arm is long. These chromosomes are : 4, 5, 6, 7, 8 and 9.3. Acrocentric p short arm is so short that it is hard to observe, but still present. There are six acrocentric chromosomes : 13,14,15,21,22 and Y chromosomes. 