Question

Organelle without a cell membrane is :

• A. ribosome
• B. nucleus
• C. mitochondria
• D. chloroplast

Answer 1

The correct option is A

ribosome

The correct option is A.

Explanation of correct option:

1. Ribosomes are the smallest and spherical organelles.
2. They are not bound by any membrane.
3. They occur either scattered in the cytoplasm or attached to the surface of the endoplasmic reticulum.
4. These are the sites for protein synthesis, hence called the protein factory of the cell.

Explanation of incorrect options:

Option B:

1. The nucleus is surrounded by two lipoprotein membranes
2. The outer membrane is continuous with the endoplasmic reticulum and may bear ribosomes on its surface, while the inner membrane is smooth.

Option C:

1. Mitochondria are membrane-bounded organelles. Mitochondria are covered by two membranes.
2. Outer membrane is porous whereas the inner membrane is deeply folded. These folds are called cristae.

Option D:

Chloroplast

1. Chloroplasts are double-membraned structures.
2. They contain a green pigment, called chlorophyll which is needed for synthesizing food through photosynthesis.

Final answer: Organelle without a cell membrane is the ribosome.