MCQs on Biotechnology: Principles and Processes – Class 12 Biology (NCERT Based)

Course: CBSE Class 12 Biology
Unit IV: Biotechnology
Topic: Biotechnology: Principles and Processes
Strictly as per NCERT | CBSE Board Exam Oriented | Concept-Clearing Explanations

Section A: Basic Principles of Biotechnology (Q1–Q15)

Q1. Biotechnology mainly deals with

A. use of chemicals in industries
B. use of living organisms for human welfare
C. study of diseases
D. plant classification

Correct Answer: B
Explanation: Biotechnology uses living organisms or their components to produce useful products and processes.

Q2. The two core techniques of modern biotechnology are

A. hybridization and mutation
B. genetic engineering and bioprocess engineering
C. cloning and breeding
D. fermentation and pollination

Correct Answer: B
Explanation: Genetic engineering alters DNA, while bioprocess engineering maintains conditions for large-scale production.

Q3. Genetic engineering involves

A. crossing of organisms
B. manipulation of DNA
C. fermentation only
D. cell division

Correct Answer: B
Explanation: Genetic engineering alters genetic material to introduce desirable traits.

Q4. Restriction enzymes are also called

A. ligases
B. molecular scissors
C. molecular glue
D. vectors

Correct Answer: B
Explanation: They cut DNA at specific sequences.

Q5. Restriction enzymes belong to the class of

A. lipids
B. carbohydrates
C. enzymes
D. hormones

Correct Answer: C
Explanation: Restriction enzymes are proteins with catalytic activity.

Q6. The first restriction enzyme was isolated from

A. Escherichia coli
B. Bacillus subtilis
C. Salmonella
D. Agrobacterium

Correct Answer: A
Explanation: Restriction endonuclease Hind II was isolated from E. coli.

Q7. Sticky ends are formed due to

A. straight cuts
B. staggered cuts
C. circular cuts
D. random cuts

Correct Answer: B
Explanation: Staggered cuts produce overhanging ends that facilitate recombination.

Q8. Blunt ends are formed when DNA is cut

A. asymmetrically
B. randomly
C. straight across both strands
D. at promoter region

Correct Answer: C
Explanation: Blunt ends lack overhangs, making ligation difficult.

Q9. DNA ligase helps in

A. cutting DNA
B. joining DNA fragments
C. unwinding DNA
D. synthesizing RNA

Correct Answer: B
Explanation: DNA ligase joins DNA fragments by forming phosphodiester bonds.

Q10. Which enzyme synthesizes complementary DNA from RNA?

A. DNA polymerase
B. RNA polymerase
C. Reverse transcriptase
D. Ligase

Correct Answer: C
Explanation: Reverse transcriptase synthesizes cDNA using RNA as template.

Q11. Cloning vectors are used to

A. cut DNA
B. transport DNA into host
C. synthesize proteins
D. mutate genes

Correct Answer: B
Explanation: Vectors carry foreign DNA into host cells.

Q12. Which is a commonly used cloning vector?

A. Virus
B. Plasmid
C. Chromosome
D. Ribosome

Correct Answer: B
Explanation: Plasmids replicate independently and carry foreign DNA.

Q13. The origin of replication in vectors is important because it

A. controls transcription
B. controls translation
C. determines copy number
D. prevents mutation

Correct Answer: C
Explanation: Ori determines how many copies of recombinant DNA are produced.

Q14. Selectable markers help in

A. cutting DNA
B. identifying recombinant cells
C. protein synthesis
D. DNA replication

Correct Answer: B
Explanation: Markers identify transformed cells from non-transformed ones.

Q15. Antibiotic resistance genes are used as

A. promoters
B. vectors
C. selectable markers
D. enzymes

Correct Answer: C
Explanation: They allow selection of transformed cells.

Section B: Tools of Recombinant DNA Technology (Q16–Q30)

Q16. Which enzyme prevents degradation of recombinant DNA in host?

A. Exonuclease
B. Endonuclease
C. Methylase
D. Ligase

Correct Answer: C
Explanation: Methylases protect host DNA from restriction enzymes.

Q17. Plasmids naturally occur in

A. plants
B. animals
C. bacteria
D. fungi

Correct Answer: C
Explanation: Plasmids are extra-chromosomal DNA in bacteria.

Q18. Bacteriophages are used as vectors because they

A. infect plants
B. infect bacteria
C. infect animals
D. are harmless

Correct Answer: B
Explanation: Bacteriophages can introduce DNA into bacteria efficiently.

Q19. Which vector is used to introduce genes into plants?

A. Plasmid pBR322
B. Bacteriophage λ
C. Ti plasmid
D. Cosmid

Correct Answer: C
Explanation: Ti plasmid from Agrobacterium tumefaciens transfers genes into plants.

Q20. The Ti plasmid causes

A. leaf curl
B. crown gall disease
C. mosaic disease
D. rust disease

Correct Answer: B
Explanation: It induces tumor formation in plants.

Q21. Reporter genes are used to

A. cut DNA
B. identify gene expression
C. replicate DNA
D. mutate cells

Correct Answer: B
Explanation: Reporter genes indicate successful gene expression.

Q22. Gel electrophoresis separates DNA fragments based on

A. shape
B. color
C. size
D. origin

Correct Answer: C
Explanation: Smaller fragments move faster through agarose gel.

Q23. Ethidium bromide is used in gel electrophoresis to

A. cut DNA
B. stain DNA
C. ligate DNA
D. amplify DNA

Correct Answer: B
Explanation: It fluoresces under UV, making DNA visible.

Q24. PCR stands for

A. Protein Chain Reaction
B. Polymerase Chain Reaction
C. Primer Copy Reaction
D. Protein Cloning Reaction

Correct Answer: B
Explanation: PCR amplifies DNA segments in vitro.

Q25. Taq polymerase is isolated from

A. E. coli
B. Thermus aquaticus
C. Bacillus
D. Agrobacterium

Correct Answer: B
Explanation: Taq polymerase is heat-stable, ideal for PCR.

Q26. PCR involves repeated cycles of

A. transcription
B. translation
C. denaturation, annealing and extension
D. replication and ligation

Correct Answer: C
Explanation: These steps amplify DNA exponentially.

Q27. Which step of PCR separates DNA strands?

A. Annealing
B. Extension
C. Denaturation
D. Ligation

Correct Answer: C
Explanation: High temperature breaks hydrogen bonds.

Q28. Annealing step in PCR allows

A. primer binding
B. DNA synthesis
C. DNA separation
D. mutation

Correct Answer: A
Explanation: Primers bind to complementary sequences.

Q29. Extension in PCR occurs at

A. 37°C
B. 50°C
C. 72°C
D. 95°C

Correct Answer: C
Explanation: Taq polymerase works optimally at 72°C.

Q30. PCR is useful for

A. protein synthesis
B. DNA amplification
C. RNA degradation
D. enzyme digestion

Correct Answer: B
Explanation: PCR produces millions of DNA copies.

Section C: Bioprocess Engineering and Downstream Processing (Q31–Q50)

Q31. Bioreactors are used to

A. store enzymes
B. culture microbes on large scale
C. cut DNA
D. mutate genes

Correct Answer: B
Explanation: Bioreactors provide controlled conditions for large-scale production.

Q32. Stirred-tank bioreactor provides

A. no oxygen
B. uniform mixing
C. low temperature
D. no nutrients

Correct Answer: B
Explanation: Agitation ensures even distribution of nutrients and oxygen.

Q33. Which component supplies oxygen in bioreactor?

A. Stirrer
B. Foam breaker
C. Sparger
D. Drain

Correct Answer: C
Explanation: Sparger bubbles air into the medium.

Q34. pH in bioreactor is maintained by

A. enzymes
B. buffers
C. antibiotics
D. vectors

Correct Answer: B
Explanation: Buffers maintain optimal pH for microbial growth.

Q35. Downstream processing includes

A. cloning
B. PCR
C. purification of products
D. DNA cutting

Correct Answer: C
Explanation: It involves separation and purification of desired products.

Q36. The final step of downstream processing is

A. fermentation
B. formulation
C. DNA isolation
D. replication

Correct Answer: B
Explanation: Formulation prepares product for market.

Q37. Recombinant protein production requires

A. vectors and host
B. enzymes only
C. fertilizers
D. sunlight

Correct Answer: A
Explanation: Foreign genes are expressed in host cells.

Q38. Which host is commonly used in biotechnology?

A. Virus
B. Protozoa
C. E. coli
D. Algae

Correct Answer: C
Explanation: E. coli grows fast and is easy to manipulate.

Q39. Inclusion bodies are

A. RNA clusters
B. protein aggregates
C. DNA fragments
D. lipid droplets

Correct Answer: B
Explanation: Overexpressed proteins often form insoluble aggregates.

Q40. Bioprocess engineering mainly focuses on

A. gene mutation
B. large-scale production
C. DNA sequencing
D. cell division

Correct Answer: B
Explanation: It scales up laboratory processes to industrial level.

Q41. Sterilization of bioreactor is necessary to

A. increase yield
B. prevent contamination
C. change genes
D. kill product

Correct Answer: B
Explanation: Contaminants reduce efficiency and product quality.

Q42. Antibiotics in culture medium are used to

A. kill host cells
B. select recombinant cells
C. promote mutation
D. increase oxygen

Correct Answer: B
Explanation: Only transformed cells survive antibiotic selection.

Q43. Recombinant DNA technology is also called

A. classical breeding
B. genetic engineering
C. mutation breeding
D. hybridization

Correct Answer: B
Explanation: It involves direct manipulation of genes.

Q44. Biotechnology products are used in

A. medicine only
B. agriculture only
C. industry only
D. medicine, agriculture and industry

Correct Answer: D
Explanation: Biotechnology has wide applications.

Q45. The yield of recombinant protein depends on

A. color of medium
B. host and culture conditions
C. size of DNA
D. number of enzymes

Correct Answer: B
Explanation: Host efficiency and conditions affect yield.

Q46. Which condition is essential for microbial growth in bioreactor?

A. absence of nutrients
B. optimal temperature
C. dry environment
D. UV light

Correct Answer: B
Explanation: Temperature affects enzyme activity and growth.

Q47. Genetic engineering allows production of

A. only enzymes
B. only hormones
C. specific proteins
D. waste products

Correct Answer: C
Explanation: Target proteins are produced using recombinant DNA.

Q48. Recombinant DNA is formed by joining

A. RNA fragments
B. protein chains
C. DNA fragments from different sources
D. chromosomes

Correct Answer: C
Explanation: DNA from different organisms is combined.

Q49. Biotechnology reduces cost of production by

A. increasing labor
B. using renewable resources
C. reducing efficiency
D. increasing pollution

Correct Answer: B
Explanation: Microbial systems are cost-effective and renewable.

Q50. The main advantage of biotechnology is

A. rapid depletion of resources
B. sustainable production of useful products
C. increased pollution
D. genetic disorders

Correct Answer: B
Explanation: Biotechnology supports sustainable development.

✅ End of MCQs – Biotechnology: Principles and Processes (Class 12 Biology, NCERT)