The long and sho arms of chromosomes are designated respectively as:
**Core Concept**
The question is testing the understanding of the structure and terminology of chromosomes. Chromosomes are composed of two main parts: the **short arm (p arm)** and the **long arm (q arm)**, which are designated by the letters "p" and "q" respectively.
**Why the Correct Answer is Right**
The **p arm** is shorter and the **q arm** is longer in most chromosomes. This distinction is essential in cytogenetics, as it helps in identifying and describing chromosomal abnormalities, such as deletions, duplications, or translocations. The arms are designated based on the position of the centromere, which is the constricted region of the chromosome where the sister chromatids are attached.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct designation of the arms. Without the correct letters, it's difficult to determine which arm is which.
**Option B:** This option is incorrect because it reverses the correct designation of the arms. The short arm is not designated as "q".
**Option C:** This option is incorrect because it does not provide any information about the designation of the arms. It's a vague and incomplete answer.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the designation of the arms (p and q) is crucial in describing chromosomal abnormalities and translocations. A simple mistake in arm designation can lead to misinterpretation of the chromosomal abnormality.
**Correct Answer: C. p and q arms.**