CBSE Class 12 Biology Very Short Answer Questions – Biotechnology: Principles and Processes (NCERT Based)

Course & Examination Details

Course: CBSE Class 12 Biology
Unit: Unit IV – Biotechnology
Chapter: Chapter 11 – Biotechnology: Principles and Processes
Prescribed Book: NCERT Biology Class XII
Question Type: Very Short Answer Questions (VSA)
Exam Relevance: CBSE Board Examinations (1–2 Mark Questions)

SECTION A: Principles of Biotechnology

Q1. What is biotechnology?

Answer: Biotechnology is the application of living organisms, cells, or biological systems to produce useful products and processes for human welfare.

Q2. State the two core principles of modern biotechnology.

Answer: Modern biotechnology is based on genetic engineering and bioprocess engineering for controlled gene manipulation and large-scale product formation.

Q3. What is genetic engineering?

Answer: Genetic engineering involves deliberate modification of genetic material to introduce desirable traits by isolating, altering, and transferring specific genes.

Q4. Define bioprocess engineering.

Answer: Bioprocess engineering ensures optimal growth conditions such as temperature, pH, and nutrients for large-scale production of biological products.

Q5. Why is biotechnology considered interdisciplinary?

Answer: Biotechnology integrates biology, chemistry, physics, engineering, and informatics to develop innovative biological products and techniques.

SECTION B: Tools of Recombinant DNA Technology – Restriction Enzymes

Q6. What are restriction enzymes?

Answer: Restriction enzymes are bacterial enzymes that cut DNA at specific recognition sequences, acting as molecular scissors in genetic engineering.

Q7. What is a palindromic DNA sequence?

Answer: A palindromic sequence reads the same in the 5′→3′ direction on both DNA strands, commonly recognized by restriction enzymes.

Q8. Differentiate between exonucleases and endonucleases.

Answer: Exonucleases remove nucleotides from DNA ends, while endonucleases cut DNA internally at specific recognition sites.

Q9. Name a commonly used restriction enzyme.

Answer: EcoRI is a widely used restriction endonuclease that recognizes the palindromic sequence GAATTC.

Q10. What are sticky ends?

Answer: Sticky ends are short, single-stranded DNA overhangs formed after restriction enzyme cleavage, facilitating efficient ligation with complementary DNA fragments.

SECTION C: Tools of Recombinant DNA Technology – Cloning Vectors

Q11. What is a cloning vector?

Answer: A cloning vector is a DNA molecule used to carry and replicate foreign DNA inside a suitable host cell.

Q12. Name two common cloning vectors.

Answer: Plasmids and bacteriophages are commonly used cloning vectors in recombinant DNA technology.

Q13. What is the function of origin of replication (ori)?

Answer: Ori initiates DNA replication, ensuring autonomous replication of the vector within the host cell.

Q14. What are selectable markers?

Answer: Selectable markers are genes, often antibiotic resistance genes, used to identify and select transformed host cells.

Q15. Why are plasmids preferred as vectors?

Answer: Plasmids are small, circular, self-replicating DNA molecules that are easy to manipulate and efficiently transfer foreign DNA.

SECTION D: Competent Host Cells

Q16. What is a competent host cell?

Answer: A competent host cell is capable of taking up recombinant DNA and supporting its replication and expression.

Q17. Name the most commonly used host organism.

Answer: Escherichia coli is the most widely used host organism in recombinant DNA technology.

Q18. How does calcium chloride treatment help transformation?

Answer: Calcium chloride increases bacterial cell wall permeability, enabling uptake of recombinant DNA during transformation.

Q19. What is heat shock in transformation?

Answer: Heat shock is a sudden temperature change that facilitates entry of recombinant DNA into competent bacterial cells.

Q20. What is electroporation?

Answer: Electroporation uses brief electrical pulses to create temporary pores in cell membranes, allowing DNA entry.

SECTION E: Processes of Genetic Engineering

Q21. What is meant by isolation of genetic material?

Answer: Isolation of genetic material involves extraction and purification of DNA from donor cells for genetic manipulation.

Q22. Why is cutting of DNA necessary in genetic engineering?

Answer: Cutting DNA produces compatible fragments that can be ligated into vectors to form recombinant DNA molecules.

Q23. What is ligation?

Answer: Ligation is the process of joining foreign DNA fragments with vector DNA using DNA ligase enzyme.

Q24. Define transformation.

Answer: Transformation is the process of introducing recombinant DNA into a competent host cell.

Q25. Why is screening of recombinants important?

Answer: Screening ensures identification of host cells containing recombinant DNA, excluding non-recombinant transformants.

SECTION F: Polymerase Chain Reaction (PCR)

Q26. What is PCR?

Answer: Polymerase Chain Reaction is an in vitro technique used to amplify specific DNA segments exponentially.

Q27. Name the enzyme used in PCR.

Answer: Taq polymerase, a thermostable DNA polymerase, is used in PCR for DNA synthesis.

Q28. Why is Taq polymerase preferred in PCR?

Answer: Taq polymerase remains stable at high temperatures required for DNA denaturation during PCR cycles.

Q29. Name the three steps of PCR.

Answer: Denaturation, annealing, and extension are the three sequential steps of PCR amplification.

Q30. Mention one application of PCR.

Answer: PCR is used in medical diagnosis for detection of genetic disorders and infectious pathogens.

SECTION G: Bioreactors

Q31. What is a bioreactor?

Answer: A bioreactor is a large vessel used for growing microorganisms or cells under controlled conditions to produce biological products.

Q32. Name one commonly used bioreactor.

Answer: The stirred-tank bioreactor is commonly used for large-scale microbial production.

Q33. Why is agitation necessary in bioreactors?

Answer: Agitation ensures uniform mixing of nutrients, oxygen, and microorganisms, enhancing product yield.

Q34. What is the role of sparger in bioreactors?

Answer: Sparger supplies oxygen evenly throughout the culture medium, supporting aerobic respiration.

Q35. Why is pH control important in bioreactors?

Answer: Maintaining optimal pH ensures proper enzyme activity and microbial growth for maximum product formation.

SECTION H: Downstream Processing

Q36. What is downstream processing?

Answer: Downstream processing involves separation, purification, and formulation of the final biological product after biosynthesis.

Q37. Why is biomass separation required?

Answer: Biomass separation removes microbial cells from the product-containing medium, enabling further purification.

Q38. Name one method of product purification.

Answer: Chromatography is commonly used to purify biological products during downstream processing.

Q39. Why is quality control essential in downstream processing?

Answer: Quality control ensures safety, purity, and efficacy of the final product, especially in pharmaceuticals.

Q40. What is formulation in downstream processing?

Answer: Formulation involves adding preservatives and stabilizers to make the product suitable for storage and use.

SECTION I: NCERT-Based Conceptual Recall

Q41. Why are restriction enzymes called molecular scissors?

Answer: They precisely cut DNA at specific recognition sites, enabling controlled genetic manipulation.

Q42. What is recombinant DNA?

Answer: Recombinant DNA is formed by joining DNA fragments from different biological sources into a single molecule.

Q43. Why are antibiotic resistance genes used as markers?

Answer: They help identify transformed cells by allowing growth in antibiotic-containing media.

Q44. What is gene cloning?

Answer: Gene cloning is the process of producing multiple copies of a specific gene using recombinant DNA technology.

Q45. Why is biotechnology important in medicine?

Answer: Biotechnology enables production of insulin, vaccines, enzymes, and therapeutic proteins for disease treatment.

SECTION J: Exam-Oriented Applications

Q46. Why is biotechnology considered environment-friendly?

Answer: It reduces chemical usage and promotes sustainable production through biological processes.

Q47. How does PCR help forensic science?

Answer: PCR amplifies minute DNA samples, enabling individual identification in forensic investigations.

Q48. What is the role of vectors in biotechnology?

Answer: Vectors transfer foreign DNA into host cells and ensure its replication and expression.

Q49. Why is E. coli widely used as a host?

Answer: E. coli grows rapidly, is easy to manipulate genetically, and supports high-level gene expression.

Q50. State one limitation of biotechnology.

Answer: Biotechnology requires strict ethical regulation due to potential misuse and environmental concerns.

Why This VSA Set Is Ideal for CBSE Class 12

✔ Strictly NCERT-based
✔ 20–30 word exam-appropriate answers
✔ Covers all sub-topics systematically
✔ Ideal for 1–2 mark questions
✔ Useful for revision & last-minute practice