Question

Which of the following is the most direct cause of polyteny in somatic cells of certain organisms?
A. RNA transcription
B. Supercoiling of chromatin
C. Chromosome replication without cell division
D. Chromosome recombination
E. Amplification of sex chromosomes

Answer 1

Hint:-Polytene chromosomes are a type of large chromosome that contains thousands of DNA strands. They are responsible for some high level of function in certain tissues such as the salivary glands of insects. These types of chromosomes are found in dipteran flies.

Complete Answer:-
Polytene chromosomes can be defined as large chromosomes that possess thousands of DNA strands. They help in the function of certain tissues such as the salivary glands of insects. Polytene chromosomes were first introduced by E.G.Balbiani in the year 1881. These types of chromosomes are mainly seen in dipteran flies. In insects, these chromosomes are commonly present in the salivary glands when the cells are not dividing.
Somatic cells are responsible for the growth and development of an organism. These cells are essential for the repair and regeneration of the different parts of the body.
Polytene chromosomes are generated when repeated rounds of DNA replication take place without cell division and form a giant chromosome. In this way, the polytene chromosomes generate when multiple rounds of replication produce many sister chromatids that stay fused.
At interphase, the polytene chromosomes have distinct thick and thin banding patterns. These patterns were usually applied to help map chromosomes, identify small chromosome mutations, and taxonomic identification. They are now also applied to study the function of genes in transcription.
So, the most direct cause of polyteny in somatic cells of certain organisms is chromosomes replication without cell division.
Thus, the right option is C.

Additional Information:-
Somatic cells refer to all the cells of the body except reproductive cells i.e. other than gametes, stem cells, and germs cells, all the cells of a multicellular organism are all called somatic cells. The diploid somatic cells go through a number of mitosis divisions. These cells originate from the body. These cells build up the entire body of the organism except the cells related to the reproductive function or are undifferentiated such as stem cells.

Note:- Polytene chromosomes are large chromosomes that possess thousands of DNA strands are mainly found in dipteran flies. These chromosomes were first introduced by E.G.Balbiani in the year 1881. These types of chromosomes are produced due to the repeated rounds of DNA replication without cell division. In the same way, chromosome replication without cell division is the most direct cause of polyteny in somatic cells of certain organisms.