Cell and molecular biology – definition, theory, basics and applications MCQs With Answer

Cell and molecular biology explores the definition, theory and basics of how cells and their molecular components function. For B.Pharm students, mastering cell structure, organelles, membranes, biomolecules, gene expression, signal transduction and cellular metabolism is vital for drug discovery, pharmacology, toxicology and biotechnology applications. This focused overview links fundamental mechanisms—DNA replication, transcription, translation, post‑translational modification and cell cycle control—to laboratory techniques such as PCR, electrophoresis, microscopy and cell culture. Emphasis on molecular targets, receptor types, second messengers and gene regulation prepares you for therapeutic strategy and diagnostics. These MCQs reinforce core concepts, experimental rationale and clinical relevance. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which cellular organelle is the primary site of ATP production through oxidative phosphorylation?

• Mitochondrion
• Ribosome
• Endoplasmic reticulum
• Golgi apparatus

Correct Answer: Mitochondrion

Q2. Which membrane transport process requires ATP and moves solutes against their concentration gradients?

• Simple diffusion
• Facilitated diffusion
• Primary active transport
• Osmosis

Correct Answer: Primary active transport

Q3. During transcription in eukaryotes, which RNA polymerase synthesizes messenger RNA (pre-mRNA)?

• RNA polymerase I
• RNA polymerase II
• RNA polymerase III
• RNA polymerase IV

Correct Answer: RNA polymerase II

Q4. Which of the following best describes a frameshift mutation?

• Single base substitution that does not change amino acid
• Insertion or deletion of nucleotides that alters the reading frame
• Change in a single base causing stop codon formation
• Large chromosomal translocation between chromosomes

Correct Answer: Insertion or deletion of nucleotides that alters the reading frame

Q5. In signal transduction, which second messenger is synthesized from ATP by adenylyl cyclase?

• Inositol trisphosphate (IP3)
• cGMP
• cAMP
• Diacylglycerol (DAG)

Correct Answer: cAMP

Q6. Which technique is commonly used to amplify a specific DNA fragment for cloning or diagnostics?

• Western blotting
• Polymerase chain reaction (PCR)
• ELISA
• Mass spectrometry

Correct Answer: Polymerase chain reaction (PCR)

Q7. Which cell cycle checkpoint primarily ensures DNA is fully replicated before mitosis?

• G1 checkpoint
• S checkpoint
• G2/M checkpoint
• M checkpoint (spindle checkpoint)

Correct Answer: G2/M checkpoint

Q8. Which enzyme removes RNA primers and fills gaps during DNA replication in prokaryotes?

• DNA ligase
• DNA polymerase I
• Helicase
• Topoisomerase

Correct Answer: DNA polymerase I

Q9. Which post-translational modification commonly targets proteins for proteasomal degradation?

• Phosphorylation
• Glycosylation
• Ubiquitination
• Methylation

Correct Answer: Ubiquitination

Q10. Which receptor type spans the membrane and directly regulates ion flow on ligand binding?

• G protein-coupled receptor (GPCR)
• Ionotropic receptor (ligand-gated ion channel)
• Receptor tyrosine kinase (RTK)
• Nuclear receptor

Correct Answer: Ionotropic receptor (ligand-gated ion channel)

Q11. Which technique separates proteins by size using an electric field in a polyacrylamide gel?

• SDS-PAGE
• Southern blot
• Northern blot
• PCR

Correct Answer: SDS-PAGE

Q12. Which cellular process is characterized by caspase activation, DNA fragmentation and membrane blebbing?

• Necrosis
• Autophagy
• Apoptosis
• Senescence

Correct Answer: Apoptosis

Q13. Which histone modification is most associated with transcriptional activation?

• Histone methylation at H3K9
• Histone deacetylation
• Histone acetylation
• DNA methylation

Correct Answer: Histone acetylation

Q14. In eukaryotic translation initiation, which complex recognizes the 5′ cap of mRNA?

• Ribosomal 60S subunit alone
• eIF4F complex
• Poly(A) binding protein alone
• tRNA charging enzyme

Correct Answer: eIF4F complex

Q15. Which molecular biology tool enables precise genome editing using a guide RNA and nuclease?

• RNAi (siRNA)
• CRISPR-Cas9
• Zinc finger electrophoresis
• Southern blotting

Correct Answer: CRISPR-Cas9

Q16. Which class of biomolecules forms the bulk of biological catalysts and drug targets in cells?

• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

Correct Answer: Proteins

Q17. Pharmacogenomics studies how genetic variation affects drug response. Which gene variant type commonly alters drug metabolism?

• Promoter GC content variations
• Single nucleotide polymorphisms (SNPs) in CYP genes
• Chromosome number variation
• rRNA sequence polymorphisms

Correct Answer: Single nucleotide polymorphisms (SNPs) in CYP genes

Q18. Which cellular compartment is the main site of lipid synthesis and detoxification of xenobiotics?

• Smooth endoplasmic reticulum
• Rough endoplasmic reticulum
• Peroxisome
• Nucleus

Correct Answer: Smooth endoplasmic reticulum

Q19. Which immune assay detects antigen–antibody interaction using an enzyme-linked color change?

• Western blot
• ELISA
• Flow cytometry
• Chromatography

Correct Answer: ELISA

Q20. Which enzyme class catalyzes transfer of phosphate groups, often regulating signaling proteins?

• Phosphatases
• Kinases
• Proteases
• Ligases

Correct Answer: Kinases

Q21. In prokaryotic gene regulation, which element binds repressors to prevent transcription initiation?

• Operator
• Terminator
• Origin of replication
• Enhancer

Correct Answer: Operator

Q22. Which viral vector is commonly used for stable gene delivery into dividing and nondividing mammalian cells?

• Adeno-associated virus (AAV)
• Lentivirus
• Bacteriophage lambda
• Retrotransposon

Correct Answer: Lentivirus

Q23. Which laboratory technique quantifies specific mRNA levels to study gene expression?

• qRT-PCR (quantitative reverse transcription PCR)
• Western blotting for protein
• SDS-PAGE
• DNA sequencing

Correct Answer: qRT-PCR (quantitative reverse transcription PCR)

Q24. Which cellular junction permits direct cytoplasmic exchange of ions and small molecules between adjacent animal cells?

• Tight junctions
• Desmosomes
• Gap junctions
• Adherens junctions

Correct Answer: Gap junctions

Q25. Which molecule is the universal electron carrier used in many metabolic reactions and exists in oxidized and reduced forms?

• DMSO
• NAD+/NADH
• ATP/ADP
• FAD/FADH2

Correct Answer: NAD+/NADH

Q26. Which process describes the selective engulfment and lysosomal degradation of cellular components for recycling?

• Apoptosis
• Necroptosis
• Autophagy
• Exocytosis

Correct Answer: Autophagy

Q27. Which type of receptor is located intracellularly and typically regulates gene transcription upon ligand binding?

• G protein-coupled receptor
• Ion channel receptor
• Nuclear receptor
• Receptor tyrosine kinase

Correct Answer: Nuclear receptor

Q28. Which laboratory method separates nucleic acids by size and transfers them to a membrane for probe detection?

• Immunoprecipitation
• Northern blot
• Southern blot
• Chromatin immunoprecipitation

Correct Answer: Southern blot

Q29. Which tumor suppressor protein is central to DNA damage response and can induce cell cycle arrest or apoptosis?

• MYC
• p53
• RAS
• BRCA1 only

Correct Answer: p53

Q30. Which statement best links cell and molecular biology to pharmaceutical applications?

• Molecular pathways rarely inform drug design, so pharmacology is separate.
• Understanding cellular mechanisms and molecular targets enables rational drug discovery and personalized therapy.
• Only clinical trials matter; cellular biology is irrelevant to therapeutics.
• Pharmaceuticals act randomly and do not depend on receptor biology or signaling.

Correct Answer: Understanding cellular mechanisms and molecular targets enables rational drug discovery and personalized therapy.

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