NEET BIOLOGY

BIOLOGICAL CLASSIFICATION

VIRUSES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which organism contains a cell membrane, ribosomes, a cell wall, a DNA loop, and has no nucleus?
A
Virus
B
Bacteria
C
Plant cells
D
Animal cells
Explanation: 

Detailed explanation-1: -Prokaryotes are single-celled organisms belonging to the domains Bacteria and Archaea. Prokaryotic cells are much smaller than eukaryotic cells, have no nucleus, and lack organelles. All prokaryotic cells are encased by a cell wall. Many also have a capsule or slime layer made of polysaccharide.

Detailed explanation-2: -Correct answer: Explanation: Prokaryotic cells differ from eukaryotic cells in that they lack any membrane-bound organelles, including a nucleus. Instead, prokaryotic cells simply have an outer plasma membrane, DNA nucleoid structure, and ribosomes.

Detailed explanation-3: -The DNA of bacterial cells is found loose in the cytoplasm. It is called chromosomal DNA and is not contained within a nucleus. Bacteria also have small, closed-circles of DNA called plasmids present in their cytoplasm. Unlike the chromosomal DNA, plasmid DNA can move from one bacterium to another giving variation.

Detailed explanation-4: -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-5: -Bacteria are prokaryotes, lacking well-defined nuclei and membrane-bound organelles, and with chromosomes composed of a single closed DNA circle.

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