CBSE Class 12 Biology Case-Based Questions with Answers – 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 Textbook: NCERT Biology Class XII
Question Type: Case-Based / Source-Based Questions
Exam Relevance: CBSE Board Examinations (Competency-Based)

SECTION A: Principles of Biotechnology

Case 1

A biotechnology company produces human insulin using genetically modified bacteria under controlled laboratory conditions.

Q1. Which principle of biotechnology is involved in introducing the insulin gene into bacteria?
Answer: Genetic engineering is involved in introducing the human insulin gene into bacterial cells.

Q2. Which second principle ensures large-scale insulin production?
Answer: Bioprocess engineering ensures optimal growth conditions for large-scale insulin production.

Case 2

A scientist modifies a gene sequence to improve protein yield.

Q3. Name the biotechnology process involved in modifying genes.
Answer: Genetic engineering is used to modify gene sequences.

SECTION B: Tools of Recombinant DNA Technology – Restriction Enzymes

Case 3

Bacterial enzymes are used to cut DNA at specific sites during gene cloning.

Q4. What type of enzymes are used to cut DNA at specific sequences?
Answer: Restriction endonucleases are used to cut DNA at specific recognition sequences.

Q5. Why are these enzymes called molecular scissors?
Answer: They precisely cut DNA at specific sites, enabling controlled genetic manipulation.

Case 4

A restriction enzyme recognizes the sequence GAATTC and cuts DNA.

Q6. Name the restriction enzyme described.
Answer: EcoRI is the restriction enzyme that recognizes the sequence GAATTC.

SECTION C: Cloning Vectors

Case 5

A plasmid carrying an antibiotic resistance gene is used to clone a foreign DNA fragment.

Q7. Why is an antibiotic resistance gene included in the plasmid?
Answer: It acts as a selectable marker to identify transformed cells.

Q8. Name the DNA molecule used to carry foreign DNA.
Answer: The plasmid acts as a cloning vector.

Case 6

A cloning vector replicates independently inside a bacterial cell.

Q9. Which vector feature allows independent replication?
Answer: The origin of replication enables independent replication inside the host.

SECTION D: Competent Host Cells

Case 7

Bacterial cells are treated with calcium chloride and exposed to heat shock.

Q10. What is the purpose of calcium chloride treatment?
Answer: It increases cell membrane permeability to facilitate DNA uptake.

Q11. What is this process of DNA entry called?
Answer: The process is called transformation.

Case 8

Electrical pulses are used to introduce DNA into cells.

Q12. Name this method of transformation.
Answer: The method is called electroporation.

SECTION E: Processes of Genetic Engineering

Case 9

DNA is isolated, cut, joined to a vector, and introduced into a host cell.

Q13. Name the enzyme used to join DNA fragments.
Answer: DNA ligase joins foreign DNA with vector DNA.

Q14. What is the final DNA molecule formed called?
Answer: The final DNA molecule is called recombinant DNA.

Case 10

Only bacteria containing recombinant DNA survive on antibiotic-containing media.

Q15. Which vector feature allows this selection?
Answer: Selectable marker genes allow identification of recombinant cells.

SECTION F: Polymerase Chain Reaction (PCR)

Case 11

A small DNA sample from a crime scene is amplified for analysis.

Q16. Name the technique used to amplify DNA.
Answer: Polymerase Chain Reaction (PCR) is used to amplify DNA.

Q17. Name the enzyme used in PCR.
Answer: Taq polymerase is used in PCR.

Case 12

PCR involves repeated heating and cooling cycles.

Q18. Name the three steps of PCR.
Answer: Denaturation, annealing, and extension are the three steps.

SECTION G: Bioreactors

Case 13

Microorganisms are grown in a large vessel with controlled temperature and pH.

Q19. What is this vessel called?
Answer: The vessel is called a bioreactor.

Q20. Name the bioreactor commonly used in industries.
Answer: Stirred-tank bioreactor is commonly used.

Case 14

Air is continuously supplied into the culture medium.

Q21. Which component of the bioreactor supplies oxygen?
Answer: The sparger supplies oxygen to the culture medium.

SECTION H: Downstream Processing

Case 15

After protein production, the product is separated and purified.

Q22. What is this final stage of biotechnology called?
Answer: This stage is called downstream processing.

Q23. Why is downstream processing essential?
Answer: It ensures purity, safety, and usability of the final product.

SECTION I: Integrated Case-Based Applications

Case 16

A pharmaceutical company uses bioreactors and purification steps to produce vaccines.

Q24. Which two major biotechnology processes are involved here?
Answer: Bioprocess engineering and downstream processing are involved.

Case 17

A gene of interest is amplified before cloning.

Q25. Why is PCR performed before gene cloning?
Answer: PCR produces multiple copies of the gene, making cloning efficient and accurate.

Why This Case-Based Set Is Ideal for CBSE Class 12

✔ Strictly NCERT-based
✔ Competency-based & application-oriented
✔ Covers entire chapter framework
✔ Follows latest CBSE case-study pattern
✔ Ideal for 5-mark case-based questions