Biotechnology: Principles and Processes — Class 12 MCQs with Answers
Class 12 CBSE Biology · Chapter 9
90 practice questions · 30 Easy · 30 Medium · 30 Hard · Updated
Practise the most important Class 12 CBSE Biology questions from Chapter 9, "Biotechnology: Principles and Processes". You get 9 timed quizzes made from 90 NCERT-based MCQs, with answers and explanations. The questions are split into 30 Easy, 30 Medium and 30 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE & Maharashtra HSC Board exams, MHT-CET and NEET UG apart.
To score well in "Biotechnology: Principles and Processes", focus on diagrams, key terms and knowing NCERT line by line. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Biotechnology: Principles and Processes, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 12 Biology mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Biotechnology: Principles and Processes (Class 12 Biology)
Biotechnology tools and processes: restriction enzymes, cloning vectors (plasmids, Ti plasmid), ligase and competent host cells; the steps of recombinant DNA technology; gel electrophoresis to separate DNA; PCR to amplify it; methods of introducing DNA into cells; and bioreactors with downstream processing.
- Restriction enzymes
- Molecular scissors — restriction endonucleases cut DNA at specific palindromic recognition sites; e.g., EcoRI cuts G^AATTC leaving sticky (cohesive) ends.
- Sticky ends
- Single-stranded overhangs left by a staggered cut; complementary overhangs from the same enzyme let vector and insert join easily via ligase.
- DNA ligase
- Molecular glue that joins DNA fragments by sealing the phosphodiester backbone; used to seal foreign DNA into a vector.
- Cloning vector
- A DNA carrier (usually a plasmid) with an origin of replication (ori), selectable markers and recognition sites; carries foreign DNA into a host.
Biotechnology: Principles and Processes — important questions & MCQs with answers (Class 12 Biology)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.
- Q1Easy
Restriction enzymes:
A.Translate proteinsB.Join DNA fragmentsC.Replicate DNAD.Cut DNA at specific sequences✓ CorrectAnswer: D. Cut DNA at specific sequences
Explanation: Restriction endonucleases recognise short palindromic sequences (e.g. GAATTC for EcoRI) and cut both strands there, acting as molecular scissors — ligase joins fragments, it doesn't cut them.
- Q2Easy
PCR (Polymerase Chain Reaction) is used to:
A.Amplify (make many copies of) a DNA segment✓ CorrectB.Cut DNAC.Translate mRNAD.Join DNAAnswer: A. Amplify (make many copies of) a DNA segment
Explanation: PCR (polymerase chain reaction) amplifies a target DNA segment exponentially in a test tube using primers and Taq polymerase — it copies DNA, it does not cut or join it.
- Q3Easy
DNA ligase:
A.Cuts DNAB.Joins DNA fragments✓ CorrectC.Unwinds helixD.TranslatesAnswer: B. Joins DNA fragments
Explanation: DNA ligase seals the sugar-phosphate backbone, forming a phosphodiester bond between adjacent nucleotides to join DNA fragments — restriction enzymes cut, ligase glues, don't swap the two.
- Q4Easy
The heat-stable DNA polymerase used in PCR is:
A.Reverse transcriptaseB.DNA ligaseC.Restriction enzymeD.Taq polymerase✓ CorrectAnswer: D. Taq polymerase
Explanation: Taq polymerase is heat-stable because it comes from Thermus aquaticus, a bacterium living in hot springs, so it survives repeated ~94-95°C denaturation without being destroyed.
- Q5Easy
The 'molecular scissors' used to cut DNA at specific sites are:
A.DNA polymeraseB.DNA ligaseC.Restriction endonucleases✓ CorrectD.HelicaseAnswer: C. Restriction endonucleases
Explanation: Restriction endonucleases are termed molecular scissors because they recognise a specific palindromic sequence and cleave both DNA strands there — Taq polymerase amplifies, it does not cut.
- Q6Easy
DNA fragments are separated according to size by:
A.PCRB.Gel electrophoresis✓ CorrectC.Centrifugation onlyD.Chromatography of gasesAnswer: B. Gel electrophoresis
Explanation: Gel electrophoresis separates DNA fragments by size: smaller fragments slip through the agarose pores faster and travel farther toward the anode than larger ones.
- Q7Medium
Common cloning vector:
A.RibosomeB.Plasmid✓ CorrectC.MitochondrionD.VacuoleAnswer: B. Plasmid
Explanation: Plasmids are small, circular, self-replicating extra-chromosomal DNA in bacteria; their independent origin of replication lets them carry and multiply a foreign gene inside the host.
- Q8Medium
PCR thermocycler key enzyme:
A.LipaseB.DNaseC.Taq DNA polymerase (heat-stable)✓ CorrectD.AmylaseAnswer: C. Taq DNA polymerase (heat-stable)
Explanation: Taq polymerase, from the thermophile Thermus aquaticus, survives the ~94-95°C denaturation step of every PCR cycle without unfolding, unlike ordinary heat-sensitive DNA polymerases.
- Q9Medium
For cloning, the vector and foreign DNA are usually cut with:
A.Different enzymes alwaysB.The same restriction enzyme (to give matching sticky ends)✓ CorrectC.DNA ligaseD.Taq polymeraseAnswer: B. The same restriction enzyme (to give matching sticky ends)
Explanation: Cutting the vector and the foreign DNA with the same restriction enzyme produces identical complementary sticky ends on both, so the insert ligates cleanly into the vector's cut site.
- Q10Medium
After n cycles of PCR, the number of copies of the target DNA becomes approximately:
A.UnchangedB.n timesC.n² timesD.2ⁿ times the original✓ CorrectAnswer: D. 2ⁿ times the original
Explanation: Because each PCR cycle doubles the DNA present, n cycles give roughly 2ⁿ-fold amplification of the target — not a linear n-fold increase, which is the tempting but wrong distractor.
- Q11Medium
Insertional inactivation identifies recombinants when foreign DNA is inserted into a:
A.Restriction site outside any geneB.The oriC.The promoter onlyD.Selectable marker gene, disrupting its function✓ CorrectAnswer: D. Selectable marker gene, disrupting its function
Explanation: Insertional inactivation inserts foreign DNA into a marker gene, such as one for antibiotic resistance, disrupting it — recombinants then lose that specific resistance while non-recombinants keep it.
- Q12Hard
Assertion: The same restriction enzyme is used to cut both vector and insert. Reason: It generates identical complementary sticky ends that ligate easily. Choose the correct option.
A.Both true and reason explains assertion✓ CorrectB.Both true, reason does not explainC.Assertion true, reason falseD.Both falseAnswer: A. Both true and reason explains assertion
Explanation: Using the same restriction enzyme on both vector and insert really does generate matching complementary sticky ends, which anneal and ligate efficiently — the reason correctly explains the assertion.
- Q13Hard
Bioreactors:
A.Cooking potsB.Large vessels for industrial culture of cells✓ CorrectC.Chemical batteriesD.BurnersAnswer: B. Large vessels for industrial culture of cells
Explanation: Bioreactors are large vessels that maintain optimum temperature, pH, substrate and oxygen for growing cells or enzymes at industrial scale to synthesise a desired biotech product.
- Q14Hard
Match: (i) Restriction enzyme (ii) Ligase (iii) Taq polymerase (iv) Lysozyme
A.i-amplifies, ii-cuts, iii-joins, iv-cutsB.i-joins DNA, ii-cuts DNA, iii-breaks wall, iv-amplifiesC.i-cuts DNA, ii-joins DNA, iii-amplifies DNA, iv-breaks cell wall✓ CorrectD.i-breaks wall, ii-amplifies, iii-cuts, iv-joinsAnswer: C. i-cuts DNA, ii-joins DNA, iii-amplifies DNA, iv-breaks cell wall
Explanation: Restriction enzymes cut DNA, ligase joins DNA, Taq polymerase amplifies DNA in PCR, and lysozyme breaks down the bacterial cell wall during DNA isolation — four distinct jobs, easy to conflate.
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Start this chapter free →Biotechnology: Principles and Processes — FAQs
What are the key concepts in Class 12 Biology Biotechnology: Principles and Processes?+
Biotechnology tools and processes: restriction enzymes, cloning vectors (plasmids, Ti plasmid), ligase and competent host cells; the steps of recombinant DNA technology; gel electrophoresis to separate DNA; PCR to amplify it; methods of introducing DNA into cells; and bioreactors with downstream processing. Key ideas include Restriction enzymes, Sticky ends, DNA ligase, Cloning vector.
What does Class 12 Biology Chapter 9 (Biotechnology: Principles and Processes) cover on XamBaaz?+
It has 90 NCERT-based MCQs on "Biotechnology: Principles and Processes": 30 Easy, 30 Medium and 30 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, MHT-CET and NEET UG.
Are these "Biotechnology: Principles and Processes" questions free to practise?+
Yes. Sign in with Google to practise "Biotechnology: Principles and Processes" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Biotechnology: Principles and Processes" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Biotechnology: Principles and Processes" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Biotechnology: Principles and Processes" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Biotechnology: Principles and Processes (Class 12 Biology)?+
The questions that matter most test Restriction enzymes, Sticky ends, DNA ligase, Cloning vector. This page shows 14 solved important MCQs with answers and explanations; all 90 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Biotechnology: Principles and Processes?+
Yes — Class 12 Biology Biotechnology: Principles and Processes has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.