Hint: Chromosomes are long DNA molecules and carry all the genetic material of an organism. The genetic materials contain the traits or the characteristics that are present in the parent generation and passed on to the offspring. The chromosomes bear the information regarding certain changes or abnormalities present which can be detected through specialized processes.
Karyotypes are known as the total chromosome count of an organism. It describes the morphological and physical details and the appearance of the chromosomes under the light microscope. The chromosomes are studied on the basis of several characteristics. The different characteristics of the chromosomes such as the length, position of the centromeres, banding pattern. This process also helps in the assessment of any differences between the sex chromosomes and any types of abnormalities.
The basic chromosome number is the number of chromosomes that are found in the somatic cells of the body. These numbers of chromosomes in the somatic cells of an individual or species is known as the somatic number. It is denoted as 2n. The other types of cells are the germ cells or the sex cells, the chromosomal number is half of the somatic cells, which is n.
In humans, the total chromosomes are 46 in the somatic cells i.e. 2n=46. Whereas, the chromosomal number of the germ cells are represented by the sex chromosomes which in the male is denoted by XY and in female, it is XX. The male contains one X chromosome and another Y chromosome and is heterogametic. But the females are homogametic and contain two X chromosomes. Therefore, the normal male karyotype can be denoted by 44 AA + XY.
The karyotype of a normal human represents 22 pairs of autosomal chromosome and one pair of sex chromosome. The sex chromosomes are also called as allosomes. In females, 2 X chromosomes and 46 autosomes are present.
The karyotype technique is utilized in the deduction of abnormalities and genetic disorders that may arise due to the chromosomes. It also helps in understanding the mechanism of genetic disorders.
Hence, the correct answer is option (B).
Note: The observed characteristics of a chromosome of an individual or a species is known as the karyotype. It exhibits the number and appearance of the chromosomes of an individual. A karyotype of a normal human male contains 22 pairs of autosomes or 44 AA and one pair of sex chromosomes or XY chromosome which is 44 AA + XY.