Select the correct statements regarding cell membrane in eukaryotic cell. A. Membrane of human RBCs has approximately 52%$52\%$ protein. B. Major phospholipids are arranged in a bilayer. C. Extensions of the plasma membrane into the cell form mesosomes. D. Tails towards the inner part of lipids are hydrophobic and thus protected from aqueous medium. E. Glycocalyx is present on the outer surface of the plasma membrane. Choose the correct answer from the options given below:

Core Logic

The nucleolus is a non-membrane-bound structure in the nucleoplasm.

It is the primary site for active ribosomal RNA (rRNA) synthesis. Cells that are highly active in protein synthesis have larger and more numerous nucleoli.

Step 1: Analyzing Other Options

• Chromatin: Contains DNA and basic proteins (histones).
• Centrosome: Organelle containing two centrioles, involved in cell division.
• Kinetochore: Disc-shaped structure on the sides of centromeres where spindle fibers attach.

Pattern Recognition

Direct factual recall: Nucleolus = rRNA synthesis factory.

Chapter Mix

Class 11 Biology: Cell The Unit of Life

Core Logic

• Centrosomes: Non-membrane bound, but found only in animal cells (eukaryotes), not in prokaryotes.
• Ribosomes: Non-membrane bound organelles universally found in all living cells (both prokaryotes and eukaryotes).
• Lysosomes: Single-membrane bound organelles found in eukaryotes.
• Mitochondria: Double-membrane bound organelles found only in eukaryotes.

Step 1: Final Conclusion

Ribosome is the only non-membrane bound organelle present in both cell types.

Pattern Recognition

Prokaryotes lack all membrane-bound organelles. The only structured organelle they possess is the ribosome (70S). Eukaryotes possess ribosomes (80S and 70S) as well.

Chapter Mix

Class 11 Biology: Cell The Unit of Life

Core Logic

Statement A is incorrect because the endomembrane system includes the endoplasmic reticulum, Golgi complex, lysosomes, and vacuoles, but does not include mitochondria. Statement E is incorrect because the mitochondrion is a double membrane-bound cell organelle, not a single membrane-bound structure. Statements B, C, and D are factually correct descriptions of the RER, semiautonomous organelles, and the cytoskeleton respectively.

Pattern Recognition

Mitochondria and chloroplasts act independently and are NOT part of the coordinated endomembrane system. They are also both double-membrane bound with their own circular DNA.

Chapter Mix

Class 11 Biology: Cell The Unit of Life