Question

The undefined nuclear region of prokaryotes is also known as

A. Nucleus

B. Nucleoid

C. Nucleolus

D. Nucleic acid

Answer 1

Hint: Prokaryotes are unicellular organisms which are not very well defined. In Prokaryotes a well-defined nuclear region is not present. It lacks membrane bound cell organelles as well.

Complete answer:

Prokaryotes are primitive in origin. True nucleus is not present in the prokaryotes. In place of the nucleus, a nucleoid is present which is a mass of genetic material only. It consists of the genetic material which is present in the form of chromatin threads with no histone proteins. The genetic material is not surrounded by nucleoplasm. It is found naked in the cytoplasm. Therefore, the unidentified nuclear region of the prokaryotic cell is known as the nucleoid. On the other hand, nucleus and nucleolus are present in the eukaryotes and nucleic acid is present in the form of chromatin threads.

Therefore, the correct answer is option “B”, that is the undefined nuclear region of prokaryotes is also known as nucleoid.

Note: Nuclear region is the region where genetic material of cells is present. Nucleus is also called the brain of the cell. In Eukaryotes, a well defined nuclear region known as the nucleus is present which is bounded by a double membranous structure. In eukaryotes, at the time of division of cells, chromatin is packed in the form of chromosomes. However, prokaryotes are unicellular organisms in which there is no nucleus present, but a nucleus like organelle known as nucleoid is present which is not bounded by any nuclear membrane. Also, in prokaryotes, plasmids (circular DNA) are present as genetic material.