Question

Which one of the following is absent in eukaryotes?
A) Nucleolus
B) Plastid
C) Mesosome
D) Ribosomes

Answer 1

Hint: Cell organelles as we know are the components of a cell. They are useful for performing different activities of the cell just like the organ system in the body. Cells perform different activities like- cell repair, blood formation, repair damaged tissues etc. Cells are the vital structures of life. As we knew, cell types are of $2$ types- animal cell and plant cell. Eukaryotes are usually seen in animal cells.

Complete answer:
Option A Nucleolus- nucleolus is the largest structure which resides in the nucleus. It helps in ribosome biogenesis. It is the major organelle in eukaryotic cell
Option A is not the correct answer.
Option B Plastid- plastids are usually significant in prokaryotic cells but they are also found in plants, algae and smaller eukaryotes too.
Option B is not the correct answer.
Option C Mesosome- mesosomes are inner folding for plasma membranes. Their only function is to provide good structure to the plasma membrane. Usually, they are found in prokaryotic cells.
Option C is the correct answer.
 Option D Ribosomes- Ribosomes are structures which are composed of ribonucleic acid and proteins and are not surrounded by any membrane. Ribosome’s main function include protein synthesis as proteins or polypeptides are formed from the surface of ribosomal membrane. Hence, they are called the protein factory of the cell engine.
Option D is not the correct answer.

Therefore, Option C is the correct answer.

Note:
As we discussed various organelles. Eukaryotic and prokaryotic organelles are \[80\]S and \[70\]S. ribosomes are the headquarters for the polypeptide synthesis. Hence, polypeptides are the building blocks of our body. And as cells are multicellular structures. So, it helps in all vital components in our bodies. Apart from ribosomes, plastid major organs like- mitochondria, Golgi apparatus, and chloroplast reside in both the cells.