NEET BIOLOGY

BIOLOGICAL CLASSIFICATION

VIRUSES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
An organism whose cells lack a nucleus
A
spirillum
B
obligate aerobe
C
prokaryote
D
chemoheterotroph
Explanation: 

Detailed explanation-1: -Prokaryotes are organisms whose cells lack a nucleus and other organelles. Prokaryotes are divided into two distinct groups: the bacteria and the archaea, which scientists believe have unique evolutionary lineages. Most prokaryotes are small, single-celled organisms that have a relatively simple structure.

Detailed explanation-2: -Eukaryotic cells have a nucleus, a membrane-bound chamber where DNA is stored, while prokaryotic cells don’t. This is the feature that formally separates the two groups. Eukaryotes usually have other membrane-bound organelles in addition to the nucleus, while prokaryotes don’t.

Detailed explanation-3: -Examples of prokaryotes are blue-green algae, bacteria and mycoplasma. Among prokaryotes, bacteria are the most common and multiply very fast. They are single-celled and range in size from 0.2 to 10 microns (about 10 times smaller than most plant and animal cells).

Detailed explanation-4: -Prokaryotes do not have a nucleus, so hence do not have a nucleolus.

Detailed explanation-5: -Prokaryotes lack an organized nucleus and other membrane-bound organelles. Prokaryotic DNA is found in a central part of the cell called the nucleoid. The cell wall of a prokaryote acts as an extra layer of protection, helps maintain cell shape, and prevents dehydration.

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