Question

All are membrane-bound cell organelles except
A. Mitochondria
B. Spherosomes
C.Ribosomes
D. Lysosomes

Answer 1

Hint: Most of the cell organelles are enclosed by a semipermeable membrane, although there are some membrane-less organelles too within the cell.
The membrane-less cell organelle among the given options are macromolecules that contain both RNA and proteins and are extremely crucial in the process of translation.

Complete answer: Ribosomes are free-floating membrane-less cell organelles in the cytoplasm. They can be divided into two subunits which are different in prokaryotes and eukaryotes.
The lack of membrane is a strategic plan in order to facilitate the process of translation where a long chain of amino acids is produced.

During the process of translation, they are bound to the ER membrane but during the rest period, they can float freely in the cytoplasm which helps them to pick up translational RNA which are essentially released from the nucleus. It also enables them to grab free amino acids and later produce long protein chains hence they have dual adaptation.
Being a non-membrane bound organelle, they are more solid in nature and are not fluid-filled along with ribosomes, cell organelles like the lysosomes, peroxisomes, Golgi bodies, and vacuoles.

So, the correct answer is option C. Ribosomes.

Note: During the extensive process of translation, the two ribosomal subunits join together just like a sandwich on the messenger RNA strand and attract the tRNA molecules. A long chain of amino acids called polypeptide chains (after undergoing post-translational processing) emerges as the ribosome decodes the mRNA sequence.