Part 7 — Critical & Complex NEET-style Questions (Q151–175)

Part 7 — Cell: The Unit of Life – Critical & Complex NEET-style Questions (Q151–175)

Q151.

Semi-autonomous organelles are called so because:
A. They depend entirely on nucleus for proteins
B. They lack any ribosomes
C. They have DNA & ribosomes but depend on nucleus for some proteins ✅
D. They can survive independently outside cell

Explanation:

• A. Entirely dependent: Wrong, they can make some proteins.
• B. Lack ribosomes: False, they have 70S ribosomes.
• **C. Correct — mitochondria & chloroplasts have DNA, ribosomes but still depend on nuclear genes.
• **D. Cannot live outside the cell.

Q152.

Which organelles support the endosymbiotic theory?
A. Nucleus & Golgi
B. Chloroplast & mitochondria ✅
C. ER & lysosome
D. Ribosome & peroxisome

Explanation:

• A. Nucleus & Golgi: Not endosymbiotic.
• **B. Correct — both double-membraned, circular DNA, 70S ribosomes → prokaryotic ancestry.
• C. ER & lysosome: Endomembrane origin, not endosymbiotic.
• **D. Ribosomes/peroxisomes: don’t have independent DNA.

Q153.

If a eukaryotic cell is treated with a drug that disrupts microtubules, which process will be affected first?
A. DNA replication
B. Protein synthesis
C. Chromosome segregation during mitosis ✅
D. Glycolysis

Explanation:

• A. DNA replication: Nucleus-based, unaffected directly.
• B. Protein synthesis: Ribosomes, not microtubules.
• **C. Correct — spindle fibers fail → improper segregation.
• **D. Glycolysis: cytosolic, unaffected.

Q154.

Deficiency of lysosomal enzyme β-glucocerebrosidase causes:
A. Alzheimer’s disease
B. Gaucher’s disease ✅
C. Diabetes mellitus
D. Night blindness

Explanation:

• A. Alzheimer’s: Neurodegenerative, unrelated.
• **B. Correct — Gaucher’s, a lysosomal storage disorder.
• **C. Diabetes: insulin deficiency.
• **D. Night blindness: vitamin A deficiency.

Q155.

Which feature is unique to prokaryotes and not found in eukaryotes?
A. 70S ribosomes in cytoplasm ✅
B. Cell membrane
C. DNA as genetic material
D. ATP production

Explanation:

• **A. Correct — prokaryotes have 70S ribosomes in cytoplasm, eukaryotes have 80S.
• **B. Both have membranes.
• **C. Both have DNA.
• **D. Both produce ATP.

Q156.

In plants, photorespiration requires coordinated function of:
A. Chloroplast, mitochondria, peroxisome ✅
B. Chloroplast, ribosome, Golgi
C. Mitochondria, ER, vacuole
D. Nucleus, mitochondria, lysosome

Explanation:

• **A. Correct — 3 organelles work together in glycolate pathway.
• B–D. Not true.

Q157.

Which of the following processes involves nuclear pores?
A. Protein synthesis
B. Export of mRNA from nucleus to cytoplasm ✅
C. ATP production
D. Ribosome peptide bond formation

Explanation:

• **A. Protein synthesis = ribosomes.
• **B. Correct — nuclear pores allow mRNA, tRNA exit & protein import.
• **C. ATP = mitochondria.
• **D. Peptide bond = ribosomes.

Q158.

Defects in microtubule-based cilia cause:
A. Sickle cell anemia
B. Kartagener’s syndrome ✅
C. Hemophilia
D. Goitre

Explanation:

• **A. Hemoglobin mutation.
• **B. Correct — immotile cilia → infertility, respiratory infections.
• **C. Clotting disorder.
• **D. Thyroid enlargement.

Q159.

In bacteria, respiration occurs in:
A. Mitochondria
B. Mesosomes ✅
C. Cytosol only
D. Ribosomes

Explanation:

• **A. Mitochondria absent.
• **B. Correct — mesosome folds increase respiratory surface.
• **C. Some enzymes in cytosol, but mesosomes are main respiratory structures.
• **D. Ribosomes = protein synthesis.

Q160.

Why is nuclear envelope considered semi-permeable?
A. Blocks all molecules
B. Allows only DNA movement
C. Allows selective exchange of RNA & proteins ✅
D. Only ions cross freely

Explanation:

• **A. Completely blocked = false.
• **B. DNA never exits.
• **C. Correct — nuclear pores regulate transport.
• **D. Not only ions.

Q161.

If a mutation prevents ATP synthase assembly, which function is directly affected?
A. Oxidative phosphorylation ✅
B. Glycolysis
C. Krebs cycle
D. Light absorption

Explanation:

• **A. Correct — ATP synthase is the enzyme for ATP production in oxidative phosphorylation.
• **B. Glycolysis = cytosol.
• **C. Krebs = mitochondrial matrix.
• **D. Light absorption = chloroplast.

Q162.

Which plastid conversion explains fruit ripening (green → red)?
A. Leucoplast → Amyloplast
B. Chloroplast → Chromoplast ✅
C. Chromoplast → Chloroplast
D. Etioplast → Chloroplast

Explanation:

• **A. Leucoplast → storage.
• **B. Correct — green chloroplasts lose chlorophyll, gain carotenoids.
• **C. Reverse occurs rarely.
• **D. Etioplasts occur in dark tissues.

Q163.

Which protein acts as a molecular motor for organelle movement on microtubules?
A. Tubulin
B. Kinesin ✅
C. Actin
D. Myosin

Explanation:

• **A. Tubulin = structural.
• **B. Correct — kinesin carries vesicles toward + end.
• **C. Actin = microfilaments.
• **D. Myosin = actin motor.

Q164.

The nucleolus is most active during:
A. Interphase ✅
B. Prophase
C. Metaphase
D. Telophase

Explanation:

• **A. Correct — interphase = rRNA synthesis, ribosome assembly.
• **B. Prophase → nucleolus starts disappearing.
• **C. Absent in metaphase.
• **D. Reforms in telophase.

Q165.

Which organelles participate in glycoprotein production?
A. Ribosome → RER → Golgi ✅
B. Lysosome → RER → ER
C. Peroxisome → Golgi → Ribosome
D. Mitochondria → ER

Explanation:

• **A. Correct — proteins made in RER → modified in Golgi → secreted.
• B–D. Wrong sequence.

Q166.

If lysosomal enzymes leak, which outcome occurs?
A. Protein synthesis
B. Apoptosis/autolysis ✅
C. ATP production
D. Cell wall synthesis

Explanation:

• **A. Ribosomes make proteins.
• **B. Correct — lysosomal leakage → cell death.
• **C. ATP: mitochondria.
• **D. Cell wall = plants.

Q167.

Mitochondrial cristae are adaptations for:
A. DNA replication
B. Increasing surface area for ATP synthesis ✅
C. Ribosome attachment
D. Nuclear envelope formation

Explanation:

• **A. DNA in matrix.
• **B. Correct — more cristae = more ETC complexes.
• **C. Ribosomes not attached here.
• **D. Unrelated.

Q168.

Which organelle is rich in hydrolytic enzymes but functions optimally at acidic pH?
A. Lysosome ✅
B. Peroxisome
C. Mitochondria
D. Ribosome

Explanation:

• **A. Correct — lysosomes have acid hydrolases, optimal at pH 5.
• **B. Peroxisomes: oxidative enzymes.
• **C. Mitochondria: ATP synthesis.
• **D. Ribosomes: protein synthesis.

Q169.

Which type of ribosome is present in both mitochondria and chloroplasts?
A. 70S ✅
B. 80S
C. 60S
D. 30S

Explanation:

• **A. Correct — 70S like prokaryotes, supports endosymbiotic theory.
• **B. 80S = cytoplasm of eukaryotes.
• C & D. Subunits, not whole ribosome.

Q170.

During plasmolysis, the space between cell wall and plasma membrane is filled with:
A. Starch
B. Hypertonic solution ✅
C. Cytoplasm
D. Air

Explanation:

• **A. Starch = storage.
• **B. Correct — external hypertonic solution enters that space.
• **C. Cytoplasm shrinks inward.
• **D. Air not involved.

Q171.

If nuclear pores are blocked, which will be affected first?
A. Protein synthesis in cytoplasm ✅
B. DNA replication
C. Glycolysis
D. Krebs cycle

Explanation:

• **A. Correct — mRNA cannot exit → no protein synthesis.
• **B. DNA replication occurs inside nucleus.
• **C. Glycolysis: cytosol, unaffected initially.
• **D. Krebs: mitochondria.

Q172.

Which cytoskeletal component is essential for vesicle transport along ER–Golgi pathway?
A. Intermediate filaments
B. Microtubules ✅
C. Collagen
D. Actin

Explanation:

• **A. Structural only.
• **B. Correct — microtubules serve as tracks for vesicle transport.
• **C. ECM protein.
• **D. Actin: local transport but not long-distance Golgi trafficking.

Q173.

Which feature distinguishes eukaryotic chromosomes from prokaryotic DNA?
A. Double-stranded DNA
B. Linear DNA with histones ✅
C. Presence of nucleoid
D. Circular DNA

Explanation:

• **A. Both have dsDNA.
• **B. Correct — eukaryotic DNA is linear, histone-bound.
• **C. Nucleoid = prokaryotes.
• **D. Circular DNA = prokaryotes.

Q174.

Defects in which structure cause infertility due to immotile sperms?
A. Lysosome
B. Flagella ✅
C. Mitochondria only
D. Ribosome

Explanation:

• **A. Lysosome: not sperm motility.
• B. Flagella (Correct): Sperm motility relies on flagellar axoneme.
• **C. Mitochondria provide energy but flagella are essential.
• **D. Ribosome: protein synthesis, not motility.

Q175.

Which sequence correctly traces the secretory pathway in eukaryotes?
A. Ribosome → ER → Golgi → Vesicle → Plasma membrane ✅
B. Ribosome → Nucleus → Golgi → Plasma membrane
C. Ribosome → Lysosome → Golgi → Plasma membrane
D. Ribosome → Chloroplast → ER → Plasma membrane

Explanation:

• **A. Correct — protein secretion follows RER → Golgi → vesicles → exocytosis.
• **B. Nucleus not directly in secretion.
• **C. Lysosomes not in secretory protein path.
• **D. Chloroplast unrelated.

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