Which one of the following is the site for active ribosomal RNA synthesis?

Related Formula

Universal non-membrane bound organelle = Ribosomes (70S in Prokaryotes, 80S in Eukaryotes)$\text{Universal non-membrane bound organelle} = \text{Ribosomes} \quad (70\text{S in Prokaryotes}, 80\text{S in Eukaryotes})$

Core Logic

Ribosomes are non-membrane-bound organelles present in all living cells, including both prokaryotes (70S) and eukaryotes (80S, as well as 70S inside mitochondria and chloroplasts). Centrosomes are non-membrane bound but present only in animal eukaryotic cells. Lysosomes and mitochondria are membrane-bound organelles.

Step 1: Conclusion

Ribosomes are found in both prokaryotic and eukaryotic cells.

Pattern Recognition

Sees: "non-membrane bound organelle in both prokaryotes and eukaryotes". Shortcut: Ribosomes (present in both).

Chapter Mix

Class 11 Biology: Cell: The Unit of Life

Related Formula

Endomembrane System = ER, Golgi, Lysosomes, Vacuoles (Excludes Mitochondria, Chloroplasts, Peroxisomes)$\text{Endomembrane System} = \text{ER, Golgi, Lysosomes, Vacuoles} \quad (\text{Excludes Mitochondria, Chloroplasts, Peroxisomes})$

Core Logic

Analysis of statements:

• A (Incorrect): Endomembrane system does NOT include mitochondria or plastids.
• B (Correct): RER has ribosomes attached to its outer surface.
• C (Correct): Both mitochondria and plastids contain semi-autonomous double-stranded circular DNA.
• D (Correct): Network of filamentous proteinaceous structures (microtubules, microfilaments, intermediate filaments) in cytoplasm is the cytoskeleton.
• E (Incorrect): Mitochondria are double-membrane bound structures.

Step 1: Conclusion

Statements B, C, and D are correct.

Pattern Recognition

Sees: "Endomembrane includes mitochondria" (False) and "Mitochondria single membrane" (False). Shortcut: Eliminate options with A or E.

Chapter Mix

Class 11 Biology: Cell: The Unit of Life

Related Formula

Human RBC Membrane: 52% Protein + 40% Lipid$\text{Human RBC Membrane: } 52\% \text{ Protein} + 40\% \text{ Lipid}$

Core Logic

Evaluating the statements for eukaryotic cell membrane:

• A (Correct): Human erythrocyte membrane contains 52% protein and 40% lipids.
• B (Correct): Phospholipids form a bilayer with polar heads pointing outward and hydrophobic tails inward.
• C (Incorrect): Mesosomes are plasma membrane extensions in prokaryotes (bacteria), not eukaryotes.
• D (Correct): Hydrophobic non-polar saturated hydrocarbon tails face inward to stay protected from the aqueous environment.
• E (Incorrect): Glycocalyx is a characteristic feature of the cell envelope of prokaryotes.

Step 1: Result

Statements A, B, and D are correct.

Pattern Recognition

Sees: "mesosomes in eukaryotic cell membrane" (False). Shortcut: Mesosomes and Glycocalyx are prokaryotic features arrow$\rightarrow$ eliminate C and E.

Chapter Mix

Class 11 Biology: Cell: The Unit of Life