Part 2 — Cell Organelles, Membrane Transport & Prokaryotic Ultrastructure (Q26–50)

Q26.

Which organelle is called the “powerhouse of the cell”?
A. Chloroplast
B. Ribosome
C. Mitochondrion ✅
D. Golgi apparatus

Explanation:

A. Chloroplast: Site of photosynthesis, not ATP powerhouse.
B. Ribosome: Protein synthesis, no ATP.
C. Mitochondrion (Correct): Produces ATP via oxidative phosphorylation → hence called powerhouse.
D. Golgi: Sorting and packaging, not energy production.

Q27.

The inner mitochondrial membrane forms folds called:
A. Cristae ✅
B. Thylakoids
C. Grana
D. Cisternae

Explanation:

A. Cristae (Correct): Folds of inner mitochondrial membrane; increase surface area for ATP synthesis.
B. Thylakoids: Membranes of chloroplasts.
C. Grana: Stacks of thylakoids in chloroplast.
D. Cisternae: Flattened sacs in ER/Golgi, not mitochondria.

Q28.

Which enzyme complex in mitochondria is responsible for ATP synthesis?
A. DNA polymerase
B. ATP synthase (F₀F₁ particles) ✅
C. Rubisco
D. RNA polymerase

Explanation:

A. DNA polymerase: DNA replication.
B. ATP synthase (Correct): Embedded in inner membrane cristae, synthesizes ATP from ADP + Pi using proton gradient.
C. Rubisco: Photosynthetic enzyme in chloroplasts.
D. RNA polymerase: Transcription, not ATP production.

Q29.

Which organelle is called the “suicidal bag of the cell”?
A. Golgi bodies
B. Lysosomes ✅
C. Vacuole
D. Ribosome

Explanation:

A. Golgi: Protein sorting.
B. Lysosomes (Correct): Contain hydrolytic enzymes; release causes autolysis → hence “suicidal bag”.
C. Vacuole: Storage.
D. Ribosome: Protein synthesis.

Q30.

The Golgi apparatus was discovered by:
A. Camillo Golgi ✅
B. Robert Hooke
C. Rudolf Virchow
D. Singer

Explanation:

A. Camillo Golgi (Correct): Identified the Golgi complex in 1898 using silver staining.
B. Hooke: Discovered cell (1665).
C. Virchow: “Omnis cellula e cellula.”
D. Singer: Proposed fluid mosaic model with Nicolson.

Q31.

Which of the following is NOT a function of Golgi apparatus?
A. Protein modification
B. Glycosylation
C. Lipid metabolism ✅
D. Lysosome formation

Explanation:

A. Protein modification: Yes, in cisternal stacks.
B. Glycosylation: Adds sugar residues to proteins/lipids.
C. Lipid metabolism (Correct): Mainly in smooth ER, not Golgi.
D. Lysosome formation: Hydrolytic enzymes packaged in Golgi.

Q32.

Which type of endoplasmic reticulum synthesizes lipids and steroids?
A. Rough ER
B. Smooth ER ✅
C. Both RER and SER
D. None

Explanation:

A. RER: Ribosome-studded, protein synthesis.
B. SER (Correct): Lipids, steroids, detoxification.
C. Both: Incorrect, specific to SER.
D. None: Wrong.

Q33.

In plant cells, the central vacuole is surrounded by:
A. Tonoplast ✅
B. Mesosome
C. Cristae
D. Thylakoid

Explanation:

A. Tonoplast (Correct): Single membrane around vacuole, regulates transport.
B. Mesosome: Infolding in bacterial membrane.
C. Cristae: Inner mitochondrial folds.
D. Thylakoid: Chloroplast membrane.

Q34.

The respiratory enzymes of the Krebs cycle are located in:
A. Outer mitochondrial membrane
B. Inner mitochondrial membrane
C. Mitochondrial matrix ✅
D. Cytoplasm

Explanation:

A. Outer membrane: Transport, not Krebs enzymes.
B. Inner membrane: Electron transport chain & ATP synthase, not Krebs cycle.
C. Matrix (Correct): Contains enzymes of Krebs cycle.
D. Cytoplasm: Glycolysis, not Krebs cycle.

Q35.

Which organelle is involved in packaging and secretion of glycoproteins?
A. Rough ER
B. Golgi apparatus ✅
C. Ribosome
D. Nucleolus

Explanation:

A. RER: Synthesis of proteins, not final packaging.
B. Golgi (Correct): Adds sugars (glycosylation), packages into vesicles.
C. Ribosome: Synthesis, no packaging.
D. Nucleolus: rRNA synthesis.

Q36.

Which organelle is known as the “kitchen of the cell”?
A. Mitochondrion
B. Chloroplast ✅
C. Ribosome
D. Golgi body

Explanation:

A. Mitochondrion: Powerhouse.
B. Chloroplast (Correct): Site of photosynthesis, food production.
C. Ribosome: Protein synthesis, not food production.
D. Golgi: Sorting.

Q37.

The space between the two mitochondrial membranes is called:
A. Matrix
B. Cristae
C. Intermembrane space ✅
D. Stroma

Explanation:

A. Matrix: Innermost compartment.
B. Cristae: Folds of inner membrane.
C. Intermembrane space (Correct): Between outer and inner membranes.
D. Stroma: Fluid of chloroplast.

Q38.

Which statement about prokaryotic DNA is true?
A. Linear and histone-bound
B. Circular and not associated with histones ✅
C. Enclosed in a nucleus
D. Double-stranded RNA

Explanation:

A. Linear: Eukaryotic feature.
B. Circular & histone-free (Correct): Bacterial DNA is usually circular and lacks histones (except in Archaea where histone-like proteins may be present).
**C. Nucleus absent in prokaryotes.
**D. RNA genome only in some viruses, not bacteria.

Q39.

Which structure in prokaryotes increases surface area for respiration?
A. Nucleoid
B. Ribosome
C. Mesosome ✅
D. Plasmid

Explanation:

A. Nucleoid: DNA region, not respiratory.
B. Ribosome: Protein synthesis.
C. Mesosome (Correct): Plasma membrane infolding, increases surface area for respiration/DNA replication.
D. Plasmid: Extra DNA.

Q40.

What type of ribosomes are found in prokaryotes?
A. 70S ✅
B. 80S
C. 60S
D. 30S

Explanation:

A. 70S (Correct): Composed of 50S + 30S subunits.
B. 80S: Found in eukaryotic cytoplasm.
C. 60S: Large subunit of eukaryotic ribosome.
D. 30S: Subunit, not complete ribosome.

Q41.

Which transport mechanism moves substances against concentration gradient using ATP?
A. Passive diffusion
B. Facilitated diffusion
C. Active transport ✅
D. Osmosis

Explanation:

A. Passive diffusion: Down gradient.
B. Facilitated diffusion: Passive, with proteins.
C. Active transport (Correct): Against gradient, ATP required.
D. Osmosis: Passive water diffusion.

Q42.

Endocytosis is absent in:
A. Amoeba
B. Animal cells
C. Plant cells ✅
D. White blood cells

Explanation:

A. Amoeba: Performs phagocytosis.
B. Animal cells: Common.
C. Plant cells (Correct): Rigid wall prevents endocytosis.
D. WBCs: Phagocytosis for defense.

Q43.

Which of the following is a single-membrane organelle?
A. Mitochondrion
B. Chloroplast
C. Lysosome ✅
D. Nucleus

Explanation:

A. Mitochondrion: Double.
B. Chloroplast: Double.
C. Lysosome (Correct): Single membrane with enzymes.
D. Nucleus: Double envelope.

Q44.

Bacterial cell wall is made of:
A. Cellulose
B. Chitin
C. Peptidoglycan ✅
D. Lignin

Explanation:

A. Cellulose: Plants.
B. Chitin: Fungi.
C. Peptidoglycan (Correct): Bacterial murein.
D. Lignin: Secondary thickening in plants.

Q45.

What is the function of plasmids in bacteria?
A. Protein synthesis
B. Provide antibiotic resistance ✅
C. Photosynthesis
D. ATP synthesis

Explanation:

A. Protein synthesis: Done by ribosomes.
B. Antibiotic resistance (Correct): Plasmids often carry resistance genes.
C. Photosynthesis: Some bacteria use pigments, not plasmids.
D. ATP synthesis: Cell membrane.

Q46.

In bacteria, DNA is located in:
A. Nucleus
B. Nucleoid ✅
C. Lysosome
D. Vacuole

Explanation:

A. Nucleus: Absent in prokaryotes.
B. Nucleoid (Correct): Irregular DNA region.
C. Lysosome: Absent in bacteria.
D. Vacuole: Not in prokaryotes.

Q47.

Which statement about vacuoles in animal cells is correct?
A. Large central vacuole occupies most of cytoplasm
B. Usually small and temporary ✅
C. Surrounded by cell wall
D. Absent completely

Explanation:

A. Large vacuole: In plants.
B. Small/temporary (Correct): In animal cells vacuoles are small and transient.
**C. Surrounded by tonoplast, not cell wall.
**D. Not absent; present but small.

Q48.

The electron transport chain in mitochondria is located in:
A. Outer membrane
B. Inner membrane (cristae) ✅
C. Matrix
D. Cytoplasm

Explanation:

A. Outer membrane: Permeable, not ETC.
B. Inner membrane (Correct): Houses ETC complexes and ATP synthase.
C. Matrix: Krebs enzymes, not ETC.
D. Cytoplasm: Glycolysis.

Q49.

Which of the following is a double-membrane organelle with its own DNA?
A. Ribosome
B. Lysosome
C. Chloroplast ✅
D. Golgi

Explanation:

A. Ribosome: Non-membranous.
B. Lysosome: Single-membrane.
C. Chloroplast (Correct): Double membrane, has DNA, RNA, 70S ribosomes.
D. Golgi: Single membrane.

Q50.

Which bacterial structure helps in conjugation (transfer of DNA)?
A. Capsule
B. Fimbriae
C. Pilus ✅
D. Flagella

Explanation:

A. Capsule: Protective layer.
B. Fimbriae: Attachment, not DNA transfer.
C. Pilus (Correct): Sex pili mediate conjugation.
D. Flagella: Motility.

(more…)

Part 2 — Cell Organelles, Membrane Transport & Prokaryotic Ultrastructure (Q26–50)