Biotechnology and Its Applications — Class 12 Biology NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 12 Biology chapter "Biotechnology and Its Applications" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 12 Biology chapter "Biotechnology and Its Applications" — 8 important questions with detailed answers for…
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NCERT Solutions for Class 12 Biology — Biotechnology and Its Applications. Step-by-step answers to all 8 textbook questions from this chapter, written for CBSE board preparation and free to use.
Biotechnology and Its Applications — All 8 Questions Solved
Q1. What is insulin? How is it produced using genetic engineering?
Insulin is a hormone produced by beta cells of pancreatic islets (islets of Langerhans). It regulates blood glucose levels and is essential for glucose metabolism.
NATURAL INSULIN:
- Protein hormone with 51 amino acids
- Two polypeptide chains (A chain: 21 amino acids, B chain: 30 amino acids)
- Connected by disulfide bonds
- Produced by pancreas in response to high blood glucose
- Promotes glucose uptake by cells, glycogen synthesis, and fat storage
PRODUCTION BY GENETIC ENGINEERING (Using E. coli):
STEP 1 - GENE ISOLATION:
- Human insulin gene (preproinsulin gene) isolated from pancreatic cells
- mRNA extracted from beta cells of pancreas
- Reverse transcriptase converts mRNA to cDNA
- cDNA cloned to get functional insulin gene
STEP 2 - MODIFICATION:
- Insulin gene ligated with expression vector plasmid
- Vector contains: ori, promoter (lac promoter), terminator, selectable marker
- Promoter controls expression of insulin gene in bacteria
- Terminator stops transcription
STEP 3 - INTRODUCTION INTO HOST:
- Recombinant plasmid introduced into E. coli by transformation
- CaCl2 method makes bacteria competent
- Recombinant plasmid taken up by bacterial cells
STEP 4 - EXPRESSION:
- Lac promoter activated by IPTG (inducer)
- RNA polymerase transcribes insulin gene
- Ribosome translates mRNA to insulin protein
- Insulin synthesized in bacterial cytoplasm
STEP 5 - PURIFICATION AND PROCESSING:
- Bacteria cultured in large fermentation tanks
- Cells harvested and lysed to extract insulin
- Insulin purified from bacterial proteins
- Since bacteria produces preproinsulin, it is processed to mature insulin
- Proteolytic enzymes cleave signal peptide
- Final insulin product has A and B chains connected by disulfide bonds
STEP 6 - QUALITY CONTROL:
- Tested for purity and identity
- Checked for biological activity
- Packaged for medical use
ADVANTAGES OF RECOMBINANT INSULIN:
1. Pure and identical to human insulin
2. Abundant supply without animal sources (eliminates ethical issues)
3. Cost-effective and economical
4. Reduced risk of contamination from animal sources
5. Standardized quality control
6. Faster production
7. Fewer side effects and better patient tolerance
8. Solves insulin shortage for diabetic patients
BRAND NAMES:
- Humulin (recombinant human insulin)
- Novolog, Humalog (insulin analogs)
CLINICAL USE:
- Treatment of Type 1 diabetes (insulin-dependent)
- Some cases of Type 2 diabetes
- Gestational diabetes
Q2. What is Bt cotton? How does Bt toxin provide pest resistance?
Bt cotton is a genetically modified cotton plant that contains genes from the bacterium Bacillus thuringiensis (Bt), making it resistant to insect pests.
BACILLUS THURINGIENSIS (Bt):
- Gram-positive soil bacterium
- Naturally produces insecticidal proteins
- Produces crystalline (Cry) proteins that are toxic to specific insects
- Different Cry proteins target different pests
- Non-toxic to humans, plants, and mammals
Bt TOXIN MECHANISM:
1. CRYSTAL PROTEIN STRUCTURE:
- Bt produces Cry proteins as crystal inclusions
- Toxin is protein with ~130-140 kDa molecular weight
- Inactive in crystalline form
2. ACTIVATION IN INSECT GUT:
- Insect ingests Bt cotton leaf containing Cry protein
- Alkaline pH and proteases in insect midgut activate toxin
- Proteolytic cleavage produces smaller active fragments
- Active toxin (65 kDa) enters insect cells
3. MODE OF ACTION:
- Toxin binds to specific receptors on midgut epithelial cells
- Forms pores in cell membrane
- Causes cell lysis (rupture)
- Leads to midgut destruction
- Insect stops feeding
- Insect dies within 2-3 days
4. SPECIFICITY:
- Cry1Ac: Effective against Heliothis (bollworm)
- Cry1Ab: Effective against Plutella (diamondback moth)
- Cry1F: Effective against Spodoptera (armyworm)
- Each toxin targets specific insect species based on receptor presence
GENETIC ENGINEERING OF Bt COTTON:
1. GENE SELECTION:
- Cry1Ac gene (or other Cry genes) selected from Bt
- Codes for insecticidal crystal protein
2. GENE PREPARATION:
- Gene isolated and modified for plant expression
- Optimized for cotton codon usage
- Added plant promoter (35S promoter) for constitutive expression
- Added polyadenylation signal for proper transcription termination
3. INTRODUCTION INTO COTTON:
- Agrobacterium tumefaciens used as vector
- Ti plasmid carries Cry gene
- Agrobacterium infects cotton cells
- Cry gene integrates into cotton chromosome
- Transgenic cotton plants regenerated from transformed cells
4. EXPRESSION:
- Cry gene expressed constitutively in all tissues
- Cotton plant produces Cry protein in leaves and other parts
- Protein levels: 0.1-1% of leaf dry weight
ADVANTAGES:
1. Reduces pesticide use by 70-90%
2. Lower cost of pest management
3. Reduces environmental pollution
4. Safer for farmworkers (less pesticide exposure)
5. Reduced harm to non-target insects
6. Higher yield and better quality cotton
7. More sustainable agriculture
LIMITATIONS AND CONCERNS:
1. Evolution of resistance:
- Some insect populations develop resistance to Bt toxin
- Resistance alleles increase in population over time
- Solution: Rotate crops, maintain refugia (non-Bt cotton), use multiple toxins
2. Biodiversity impacts:
- May affect non-target organisms
- Potential ecological consequences
- Requires monitoring
3. Gene flow:
- Bt genes may transfer to wild cotton species
- Long-term ecological effects unclear
4. Cost and accessibility:
- Seed cost higher than conventional cotton
- May not be affordable for all farmers
GLOBAL ADOPTION:
- India is the largest producer of Bt cotton
- Widely adopted in USA, China, Australia
- Covers millions of hectares globally
Q3. Explain gene therapy. Give an example of a genetic disease treated by gene therapy.
Gene therapy is a medical technique that involves introducing genetic material into a patient's cells to treat, cure, or prevent disease. It corrects defective genes or provides new genetic functions.
TYPES OF GENE THERAPY:
1. SOMATIC GENE THERAPY:
- Targets body cells (non-reproductive cells)
- Genetic changes are not inherited
- Affects only treated individual
- Most gene therapy today is somatic
- Ethically less controversial
2. GERMLINE GENE THERAPY:
- Targets reproductive cells (egg, sperm, embryo)
- Genetic changes pass to offspring
- Heritable changes in population
- Currently not permitted in humans in most countries
- More ethically controversial
GENE THERAPY APPROACHES:
1. GENE REPLACEMENT:
- Introduce normal copy of defective gene
- Corrects genetic deficiency
- New gene produces functional protein
2. GENE EDITING:
- Correct mutation in existing gene
- Uses CRISPR-Cas9 or other techniques
- Repairs broken or mutated gene
3. GENE ADDITION:
- Add new gene with therapeutic function
- Produces missing protein
- Does not necessarily replace defective gene
DELIVERY METHODS:
1. VIRAL VECTORS:
- Modified viruses carry therapeutic gene
- Types: Adenovirus, Retrovirus, Lentivirus, AAV
- Efficiently deliver genes into cells
- Natural ability to penetrate cell membrane
2. NON-VIRAL METHODS:
- Direct injection of naked DNA/RNA
- Lipofection (liposomes)
- Electroporation
- Gene gun (microparticles)
- Less efficient but safer
EXAMPLE: SEVERE COMBINED IMMUNODEFICIENCY (SCID) - ADA DEFICIENCY
DISEASE:
- SCID ("Bubble Boy" disease) caused by deficiency in adenosine deaminase (ADA) enzyme
- Without ADA, toxic metabolites accumulate
- Destroys immune cells (T cells and B cells)
- Causes severe immunodeficiency
- Patients vulnerable to all infections
- Without treatment, usually fatal in infancy
- No functional immune system
GENE THERAPY TREATMENT:
1. CELLS SELECTED:
- Patient's own T lymphocytes (immune cells) isolated
- Cultured in laboratory to increase numbers
2. GENE INTRODUCTION:
- Normal ADA gene introduced into T cells
- Using retroviral vector as delivery vehicle
- Gene integrates into cell chromosome
- T cells now produce functional ADA enzyme
3. REINTRODUCTION:
- Treated T cells returned to patient's bloodstream
- Cells circulate and provide ADA activity
- Prevent accumulation of toxic metabolites
- Allow normal immune function
4. RESULTS:
- Immune system restored
- Patient gains protection against infections
- Multiple treatments may be necessary as cells die
- Successfully treated patients have lived for years
- First successful human gene therapy (1990s)
OTHER GENETIC DISEASES TREATED:
- Hemophilia B: Factor IX gene therapy
- Spinal muscular atrophy (SMA): SMN gene replacement
- Leber congenital amaurosis: RPE65 gene therapy
ADVANTAGES:
1. Treats root cause of genetic disease
2. May provide permanent cure
3. Reduces need for ongoing symptomatic treatment
4. Improves quality of life
5. Can prevent serious complications
CHALLENGES:
1. Delivery to specific tissues is difficult
2. Ensuring therapeutic gene expression
3. Immune responses against vectors
4. Random integration may cause new problems
5. High cost
6. Long-term effects unknown
7. Ethical concerns about germline therapy
8. Limited gene transfer efficiency
Q4. What are GMOs (Genetically Modified Organisms)? Give examples and discuss their advantages and concerns.
GMOs (Genetically Modified Organisms) are organisms whose genetic material has been altered using genetic engineering techniques to introduce traits that do not occur naturally through traditional breeding. The aim is to improve crop/organism characteristics.
Q5. Explain DNA fingerprinting and its applications in forensics.
DNA fingerprinting (DNA profiling) is a technique used to identify and distinguish individuals based on their unique DNA patterns. Each person (except identical twins) has a unique DNA sequence, making this a powerful identification tool.
Q6. What is CRISPR-Cas9? How does it function as a gene-editing tool?
CRISPR-Cas9 is a revolutionary gene-editing technology derived from bacterial immune systems. It allows precise editing of DNA sequences in living organisms.
Q7. Describe the use of microorganisms in production of antibiotics like penicillin.
Microorganisms are used extensively in the industrial production of antibiotics, which are compounds that kill or inhibit growth of bacteria and other pathogens.
Q8. What is personalized medicine? How does genomics contribute to personalized medicine?
Personalized medicine (precision medicine) is an approach to medical treatment that tailors therapy to individual patients based on their genetic makeup, lifestyle, and environmental factors rather than using a one-size-fits-all approach.
Biotechnology and Its Applications — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. Which of the following genes is responsible for producing an insecticidal protein in Bt cotton?
- A. cryIIAb
- B. lacZ
- C. tetR
- D. ampr
Answer: A. cryIIAb — The genes like `cryIAc` and `cryIIAb` encode crystal proteins from *Bacillus thuringiensis* that are toxic to specific insect pests like cotton bollworms.
MCQ 2. In the production of Humulin, why were two separate DNA sequences, corresponding to A and B chains, introduced into *E. coli* plasmids?
- A. To ensure proper folding of the entire pro-insulin molecule.
- B. To facilitate the subsequent removal of the C-peptide.
- C. Because mature insulin lacks the C-peptide and is directly functional as A and B chains.
- D. To prevent degradation of the insulin chains within the bacterial cell.
Answer: C. Because mature insulin lacks the C-peptide and is directly functional as A and B chains. — Mature insulin consists of two polypeptide chains (A and B) linked by disulfide bonds. In humans, pro-insulin is processed by removing the C-peptide, but *E. coli* lacks this processing mechanism, so A and B chains are produced separately and then assembled *in vitro*.
MCQ 3. The first clinical gene therapy was given in 1990 to a 4-year-old girl with a deficiency of which enzyme?
- A. Tyrosine hydroxylase
- B. Adenosine deaminase (ADA)
- C. Phenylalanine hydroxylase
- D. Hexosaminidase A
Answer: B. Adenosine deaminase (ADA) — The first successful clinical gene therapy was performed in 1990 on a 4-year-old girl with Severe Combined Immunodeficiency (SCID) due to adenosine deaminase (ADA) deficiency.
MCQ 4. Transgenic mice are being developed for all of the following purposes EXCEPT:
- A. To study how genes contribute to the development of disease.
- B. To test the safety of vaccines and chemicals.
- C. To produce useful biological products like human protein alpha-lactalbumin.
- D. To enhance their speed and agility for competitive sports.
Answer: D. To enhance their speed and agility for competitive sports. — Transgenic animals are primarily created for medical research (disease models, vaccine safety), production of therapeutic proteins, and physiological studies, not for enhancing physical performance in sports.
MCQ 5. RNA interference (RNAi) involves the production of complementary RNA molecules that bind to and prevent the translation of specific mRNA molecules. This mechanism is crucial in:
- A. Protecting plants from bacterial infections.
- B. Inducing mutations in target genes for gene editing.
- C. Developing pest resistance in plants, like against nematodes.
- D. Enhancing the nutritional content of genetically modified crops.
Answer: C. Developing pest resistance in plants, like against nematodes. — RNAi is a method of cellular defense in eukaryotes. It is used in biotechnology to develop pest resistance in plants, for example, *Meloidegyne incognitia* (nematode) resistant tobacco plants, by silencing specific nematode genes.
MCQ 6. Which of the following techniques is commonly used for early diagnosis of diseases by amplifying specific DNA sequences?
- A. ELISA
- B. Electrophoresis
- C. PCR (Polymerase Chain Reaction)
- D. Western Blotting
Answer: C. PCR (Polymerase Chain Reaction) — PCR is a powerful technique to amplify specific DNA fragments, making it useful for detecting very low concentrations of pathogens or specific gene mutations early in disease diagnosis.
MCQ 7. The term 'biopiracy' refers to:
- A. The illegal use of genetically modified organisms for commercial purposes.
- B. The unauthorized exploitation of bio-resources without proper authorization from the concerned country and without compensatory payment.
- C. The process of modifying the genetic makeup of an organism for agricultural benefits.
- D. The patenting of synthetic genes developed in laboratories.
Answer: B. The unauthorized exploitation of bio-resources without proper authorization from the concerned country and without compensatory payment. — Biopiracy is the term used for the unauthorized use of biological resources and traditional knowledge by multinational companies and other organizations without proper authorization from the countries and people concerned, often without compensatory payment.
MCQ 8. In the gene therapy for ADA deficiency, lymphocytes are periodically infused into the patient. Why is this repeated infusion necessary?
- A. The introduced genes degrade quickly in the lymphocytes.
- B. Lymphocytes have a limited lifespan and need to be replaced.
- C. The host immune system rejects the modified lymphocytes over time.
- D. The corrective genes are only transiently expressed in the cells.
Answer: B. Lymphocytes have a limited lifespan and need to be replaced. — In this approach, lymphocytes are not immortal. They have a limited lifespan, so periodically a fresh culture of genetically engineered lymphocytes needs to be introduced into the patient.
MCQ 9. Which of the following is an example of a genetically modified crop designed for pest resistance?
- A. Golden Rice
- B. Flavr Savr tomato
- C. Bt Cotton
- D. Super Sweet Corn
Answer: C. Bt Cotton — Bt cotton is genetically engineered with genes from *Bacillus thuringiensis* to produce insecticidal proteins, making it resistant to certain insect pests like bollworms.
MCQ 10. ELISA (Enzyme-Linked Immunosorbent Assay) is based on the principle of:
- A. Amplification of specific DNA sequences.
- B. Antigen-antibody interaction.
- C. Separation of proteins based on size and charge.
- D. Detection of gene mutations using probes.
Answer: B. Antigen-antibody interaction. — ELISA is a diagnostic tool that relies on the specific binding of antibodies to antigens, forming an antigen-antibody complex that can then be detected via an enzyme reaction.
MCQ 11. The Government of India has set up an organization called GEAC. What is its primary function?
- A. To promote the use of genetically modified crops in agriculture.
- B. To regulate the development of new biotechnological products.
- C. To make decisions regarding the validity of GM research and the safety of introducing GM organisms for public services.
- D. To provide financial assistance for biotechnology research projects.
Answer: C. To make decisions regarding the validity of GM research and the safety of introducing GM organisms for public services. — GEAC (Genetic Engineering Appraisal Committee) is responsible for assessing the safety of genetically modified organisms and products before their public release, considering both ethical and environmental concerns.
MCQ 12. In the production of human insulin by biotechnology, the A and B chains are produced separately in *E. coli* and then joined *in vitro*. What type of bond is formed between these chains to create functional insulin?
- A. Hydrogen bonds
- B. Peptide bonds
- C. Disulfide bonds
- D. Ionic bonds
Answer: C. Disulfide bonds — The functional human insulin molecule consists of two polypeptide chains, A and B, which are linked together by disulfide bonds (S-S bonds) formed between cysteine residues.
MCQ 13. The first transgenic cow, Rosie, produced milk enriched with which human protein?
- A. Alpha-1-antitrypsin
- B. Alpha-lactalbumin
- C. C-peptide
- D. Growth hormone
Answer: B. Alpha-lactalbumin — Rosie, the first transgenic cow, produced milk containing human alpha-lactalbumin, which is nutritionally more balanced for human babies than natural cow milk.
MCQ 14. Gene therapy is a method to correct a gene defect by delivering a functional gene into an individual's cells. This technique is primarily used to treat:
- A. Infectious diseases like malaria.
- B. Genetic disorders.
- C. Autoimmune diseases.
- D. Allergic reactions.
Answer: B. Genetic disorders. — Gene therapy aims to treat genetic disorders by replacing a defective gene with a functional one or by introducing a new gene to provide a therapeutic effect.
MCQ 15. The Bt toxin protein, when ingested by an insect, gets activated in the gut. This is because:
- A. The insect's digestive enzymes directly activate the protoxin.
- B. The alkaline pH of the insect gut solubilizes the inactive protoxin.
- C. The acidic pH of the insect gut breaks down the protein, releasing the active toxin.
- D. Specific receptors in the insect gut cells bind to the protoxin, causing activation.
Answer: B. The alkaline pH of the insect gut solubilizes the inactive protoxin. — The Bt toxin protein exists as inactive protoxins in the *Bacillus thuringiensis* bacterium. Upon ingestion by an insect, the alkaline pH of the insect gut solubilizes these crystal proteins, converting them into their active form.
MCQ 16. In the context of RNA interference (RNAi) used to develop pest resistance in tobacco plants against the nematode *Meloidegyne incognitia*, what is the source of the complementary RNA that silences the nematode's specific mRNA?
- A. Synthesized by the plant itself in response to nematode infection.
- B. Introduced into the plant as a transgenic construct containing DNA that produces both sense and anti-sense RNA.
- C. Directly absorbed by the plant from the soil where the nematodes reside.
- D. Secreted by symbiotic bacteria living within the plant roots.
Answer: B. Introduced into the plant as a transgenic construct containing DNA that produces both sense and anti-sense RNA. — The nematode-specific genes are introduced into the plant using *Agrobacterium* vectors. This DNA produces both sense and anti-sense RNA in the host plant, forming double-stranded RNA (dsRNA) that triggers RNAi and silences the nematode's corresponding mRNA.
MCQ 17. Golden Rice is a genetically modified crop designed to be enriched with:
- A. Vitamin C
- B. Iron
- C. Vitamin A
- D. Protein
Answer: C. Vitamin A — Golden Rice is genetically engineered to produce beta-carotene, a precursor to Vitamin A, to combat Vitamin A deficiency in regions where rice is a staple food.
MCQ 18. Why are conventional methods of diagnosis (like serum and urine analysis) often insufficient for early detection of diseases?
- A. They are too expensive and time-consuming.
- B. They provide inaccurate results for most diseases.
- C. They only detect the presence of pathogens or disease symptoms when their concentration is already very high.
- D. They require specialized equipment not widely available.
Answer: C. They only detect the presence of pathogens or disease symptoms when their concentration is already very high. — Conventional diagnostic methods detect disease when symptoms appear, which means the pathogen concentration or disease effects are already significant. Molecular methods like PCR and ELISA can detect very low concentrations, allowing for early diagnosis.
MCQ 19. What is a major concern often raised regarding the consumption of genetically modified (GM) foods?
- A. They are generally less nutritious than conventional foods.
- B. They might lead to the development of new plant diseases.
- C. They could cause allergic reactions and antibiotic resistance in humans.
- D. They have a shorter shelf life compared to non-GM foods.
Answer: C. They could cause allergic reactions and antibiotic resistance in humans. — Major concerns about GM foods include potential allergic reactions due to novel proteins and the possibility of transferring antibiotic resistance genes (often used as selectable markers in genetic engineering) to human gut bacteria, though scientific consensus generally finds approved GM foods safe.
MCQ 20. Which of the following is a common trait introduced into plants through genetic modification to benefit agriculture?
- A. Enhanced sugar content for sweetness.
- B. Increased susceptibility to herbicides.
- C. Tolerance to abiotic stresses (e.g., cold, drought, salinity, heat).
- D. Reduction in nutrient uptake from soil.
Answer: C. Tolerance to abiotic stresses (e.g., cold, drought, salinity, heat). — Genetic modification often aims to improve crop resilience by introducing genes that confer tolerance to environmental stresses like drought, salinity, or extreme temperatures.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.