Question

Polytene chromosome discovered in
A. Chironomus
B. Drosophila
C. Musca
D. Culex

Answer 1

The polyethylene chromosome is also a giant chromosome, but it is relatively smaller than the lampbrush chromosome. These striped chromosomes are found in the salivary glands of the larva, the epithelium of the middle and rectum, and also in the Malpighian tubules of various genera. In these larvae, the salivary glands contain salivary cells large enough to be easily seen with the lens of a surgical microscope.

Complete answer:
First of all, let’s start with the definition of the Polytene chromosome
Polytene chromosomes are large chromosomes with thousands of strands of DNA. They provide a high level of functionality in certain organizations such as B. Salivary glands of insects.
Polytene chromosomes have a series of dark stripes along their length, alternating light or medium stripes. Dark stripes represent narrow or wide disc-like structures.
They are euchromatic in nature and contain large amounts of DNA, small amounts of RNA, and some essential proteins. The rim is positive and absorbs ultraviolet rays (UV). The light or middle stripe is a negatively rimmed fibrous dichroic region containing a small amount of DNA. It has a large amount of RNA and protein acids and absorbs small amounts of ultraviolet radiation. The number, distribution, and arrangement of the plates or stripes are very similar to the chromosomes of homologous Drosophila pennies. The centers of all these chromosomes combine to form chromosomes in Drosophila. At certain stages of development, individual chains or bands of adjacent log chromosomes cause localized, reversible edema called "chromosomal edema" or precursor.
Polytene chromosomes were first described by E. G. Balbiani. Polytene chromosomes are on the biplane. The best-studied are Drosophila, Chironomus, and Rhynchosciara. They are present in the arthropods Collembola, the Ciliophora group of protozoa, mammalian trophoblasts, and other groups of antipodal and suspensor cells in plants. In insects, they are often found in the salivary glands when cells are not dividing.
So, the correct answer is “Option A”.

Note:
Because of their large chains, they are called the Polytene chromosome (a name suggested by Kollar) or, more commonly, the salivary gland chromosome. The latter term is misused because these chromosomes can be found in other somatic cells in the body besides salivary gland cells. Not only can Polytene cells expand the cell's nucleus and trigger cell growth, but they can also have metabolic benefits as multiple gene copies provide high levels of gene expression. In Drosophila melanogaster, for example, the chromosomes of the salivary glands of the larva go through several sustained cycles of proliferation, producing large amounts of sticky mucous proteins ("glues") in front of the cocoon.