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Drosophila melanogaster has 8 chromosomes in its somatic cells. the number of possible linkage groups is
a)4
b)8
c)2
d)5

Answer
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Hint: Linkage is the tendency of the genes located on the same chromosome to stay together in hereditary transmission. The genes which are positioned on the same chromosome are referred to as the linked genes. Linkage was the term put forward by Thomas Hunt Morgan in 1910.

Complete answer:
The linkage is known as the tendency of genes located on the same chromosome to remain together in the genetic transmission. The genes which are located on the same chromosome are called the linked genes. Based on the experiments done on Drosophila melanogaster by Thomas Hunt Morgan the term linkage was coined by him in the year 1910. The fruit fly has 8 chromosomes which means it has 4 pairs of chromosomes. So, the number of possible linkage groups in Drosophila melanogaster is 4 due to the presence of 4 pairs of chromosomes. The linkage groups are counted on the basis of the number of pairs of homologous chromosomes present. If there is the presence of a heterozygous chromosome then they are counted individually and not in pairs. Like in human males there is the presence of 25 linkage groups and in females, there is the presence of 24 linkage groups.
So, the correct answer is ‘4’.

Note: The linkage is known as the tendency of genes located on the same chromosome to remain together in the genetic transmission. The linkage groups are counted on the basis of the number of pairs of homozygous chromosomes present like in human females. If there is the presence of a heterozygous chromosome then they are counted individually and not in pairs like in a human male.