Question

Which one is an organelle within an organelle
A)ER
B)Mesosomes
C)Peroxisomes
D)Ribosome

Answer 1

RNA and associated proteins are included in these organelles that generally function for synthesizing the proteins which are needed for many cellular functions like repairing damage or directing the chemical processes. It can be found on both cytoplasms or on the endoplasmic reticulum.

Complete answer
-Organelle is a specialized subunit that is found within cells and has specific functions. They are either enclosed within their own lipid bilayers i.e. membrane-bound organelles or without a surrounding lipid bilayer i.e. non-membrane bound organelles.
-These unique structures help in translating the DNA code with the messenger RNA into the actual proteins used by the cells for different processes are known as Ribosomes. They have no membrane around them that's why they are different from other organelles.
-Except for the mammalian erythrocytes and red blood corpuscles, ribosomes found in all the living cells. Ribosomes are of two types depending on the place of their occurrence.
1)The ribosomes that remain free in the cytoplasm matrix are known as cytoplasmic ribosomes i.e
cyto ribosomes and also can be found attached to the cytosol and on the surface of the endoplasmic reticulum. They are attached with the help of special ribophorin or SRP proteins.
2)Ribosomes are also found in the plastid and mitochondria. Ribosomes present in the plastid known as plasti ribosomes and that in the mitochondria are known as mitoribosomes.
-SOS types of ribosomes are present in cytoplasmic ribosomes and 70s ribosomes are present in organelles in eukaryotic cells.

Additional information
Endoplasmic reticulum (ER) -in a eukaryotic cell, it forms a series of flattened sacs in the cytoplasm and provides many different functions mainly in the synthesis, folding modification, and transport of proteins.
Peroxisomes - it is found in the cytoplasm and a membrane-bound organelle of all the eukaryotic cells. It helps in the oxidation of specific biomolecules and contributes to the biosynthesis of membrane lipids known as plasmalogens. In-plant cells, it helps in the recycling of carbon from phosphoglycolate during photorespiration.
Mesosomes - it looks the same as an infolding of the plasma membrane and many functions performed by it like DNA replication, cell division, and excretion of exoenzymes.

So, the correct answer is,” Ribosomes”.

Note:
-Ribosomes function as a micromachine for producing proteins. It mainly comprises special proteins and nucleic acids.
-80s ribosomes are attached to the rough endoplasmic reticulum which is an organelle in eukaryotic cells.
-In chloroplast and mitochondria it is also present.
Therefore, it is known as organelles within an organelle.