Question

The shorter and the longer arm of the submetacentric chromosome are referred to as
A. S-arm and I-arm respectively
B. P-arm and q-arm respectively
C. Q-arm and p-arm respectively
D. M-arm and n-arm respectively

Answer 1

Submetacentric chromosomes are the chromosomes whose centromere is located near the middle. Both the arms differ slightly in length and can also be seen in L-shape.

Complete Answer:
- The chromosomes are found in the nucleus which consists of DNA which is thread like structure. A chromosome consists of sister chromatids called the arm and centromere at the middle to which the arm attaches.
- When both the arms are of similar length then the chromosome is called metacentric chromosome. But when the arms are not similar in length, then it is known as a submetacentric chromosome.
- The submetacentric chromosomes appear as L shaped. The two arms of the chromosome are referred to as P-arm and Q-arm. The p-arm is the shorter arm whereas the q arm is the longer arm as shown in the diagram.

Thus the correct answer is (B). The shorter and the longer arm of the submetacentric chromosome are referred to as p-arm and q-arm.

Additional Information:
The other two types of chromosome are-
(I) Telocentric- When the centromere is located at the end of the chromosome.
(II) Acrocentric- When the P-arm is too short.

Note: Centromere is the dense and constricted region of chromosome. In the meiosis the crossing over takes place between the arms. The metacentric chromosomes appear V-shaped.