Biotechnology, Genetics and Health

The governing principle is that the genetic code is essentially universal, so a coding sequence taken from any organism can in principle be read by the transcription and translation machinery of any other, provided a suitable promoter and delivery vector are supplied. Taxonomic distance is a technical obstacle, not a barrier of kind.

• Statement 1 is correct and is the least demanding of the three; transfer between plant species is the oldest and commonest application, seen in herbicide tolerance and virus resistance traits moved across crop species.
• Statement 2 is correct. Animal to plant transfer is well established, the standard classroom examples being fish antifreeze protein genes introduced into plants for cold tolerance and mammalian genes expressed in plant systems for molecular farming of pharmaceutical proteins.
• Statement 3 is correct and is the most familiar of all in the Indian context: the cry genes of the soil bacterium Bacillus thuringiensis transferred into cotton and brinjal are a microorganism to higher organism transfer. All three being correct, the official answer is (d). There is no elimination route here and none is needed, since the universality of the code makes the whole set follow from a single principle.

The governing principle is the route of transmission, and tattooing transmits disease by one route only, percutaneous inoculation of infected blood through a contaminated needle.

• Item 2, hepatitis B, qualifies and is the most efficiently transmitted of the three by this route, the virus being highly stable outside the body and infectious at very low inoculum, which is why hepatitis B and hepatitis C are the classic tattooing and unsafe injection risks.
• Item 3, HIV, qualifies, needle borne transmission being well established, though the per exposure risk is considerably lower than for hepatitis B.
• Item 1, chikungunya, does not qualify. It is an arbovirus transmitted by the bite of infected Aedes aegypti and Aedes albopictus mosquitoes, and its epidemiology is entirely vector borne; a brief viraemia exists, so transfusion associated transmission is theoretically possible, but it is not a disease transmitted by tattooing in any practical sense and is not so classified. The official answer (b) follows. The elimination route is chikungunya alone, which appears in options (a), (c) and (d), so recognising it as vector borne settles the question in one step without needing to weigh the relative risk of the other two.

• Statement 3 alone is correct. Smallpox is the only human disease ever to have been eradicated. The last naturally occurring case in India was recorded in 1975, India was certified free of smallpox in 1977, and global eradication was certified by the World Health Organization in 1980 following the intensified programme built on surveillance, containment and ring vaccination.
• Statement 1 is incorrect. Diphtheria has been greatly reduced by DPT immunisation but continues to occur in India, with recurrent outbreaks in under-immunised populations; controlled is not eradicated.
• Statement 2 is incorrect. Chickenpox, caused by varicella zoster virus, remains endemic; varicella vaccine is not part of India's Universal Immunisation Programme, and because the virus establishes lifelong latency in dorsal root ganglia and reactivates as herpes zoster, it has a reservoir that makes eradication far harder than for smallpox. The official answer is (b). The governing distinction is between eradication, meaning permanent reduction of worldwide incidence to zero so that intervention can cease, elimination, meaning reduction to zero in a defined geographical area, and control. Smallpox was uniquely eradicable because it had no animal reservoir, no latent or carrier state, and a visible rash that made every case detectable.

A transgenic crop is one into which a gene from outside the sexually compatible gene pool has been introduced, so the test for each item is whether it is a route by which foreign DNA is put into and expressed in a plant.

• Statement 1 is incorrect. Budding and grafting join the tissues of two plants so that they grow as one, but the scion and the stock retain their own genomes and no genetic material is transferred or recombined; it is a horticultural propagation technique of great antiquity and has nothing to do with transformation.
• Statement 3 is correct. Gene silencing, whether by antisense RNA or by RNA interference through the introduction of a construct producing double-stranded RNA, is achieved by inserting an engineered construct into the plant genome, so the resulting plant is transgenic; the delayed-ripening tomato and virus-resistant papaya are the standard examples, and RNA interference constructs against insect target genes are a current line of work.
• Statement 2 is treated as correct by the key. In its classical form cytoplasmic male sterility is a naturally occurring mitochondrial trait used in conventional hybrid seed production and involves no transgene at all, so the key must rest on the engineered male sterility systems, of which the barnase and barstar system is the leading example, where a ribonuclease gene under a tapetum-specific promoter is inserted to abolish pollen production and a matching inhibitor gene restores fertility in the hybrid. The official answer is (b).
• Statement 1 is the only one that can be rejected without hesitation, and doing so removes (a) and (c), after which the item turns on statement 2 between (b) and (d).

• Pairs 1 and 2 are correctly matched and pair 3 is not, so the official answer is (a).
• Pair 1 is correct: ascorbic acid is a cofactor for the hydroxylation of proline and lysine residues in procollagen, and without that hydroxylation the collagen triple helix is unstable, which is why deficiency produces the bleeding gums, poor wound healing, loose teeth and perifollicular haemorrhages of scurvy.
• Pair 2 is correct: vitamin D is required for the absorption of calcium from the gut and for normal mineralisation of the growing bone, and deficiency in children produces rickets, with bowing of the long bones and costochondral beading, the corresponding adult condition being osteomalacia.
• Pair 3 is incorrect: night blindness is the deficiency disease of vitamin A, because retinal, the aldehyde form of the vitamin, combines with opsin to form rhodopsin, the pigment of the rod cells that mediates vision in dim light, and its absence progresses through nyctalopia to xerophthalmia and keratomalacia. Vitamin E is an antioxidant tocopherol whose deficiency, uncommon in humans, presents with haemolysis and neurological signs. The item is decided on pair 3, and the vitamin A association with vision is among the most secure facts in the syllabus, so its rejection removes (b), (c) and (d) together.

• Option (b) is correct. The West African Ebola epidemic of 2014 to 2016, the largest on record, was centred on Guinea, where the index case was traced to Meliandou in December 2013, and on the neighbouring states of Liberia and Sierra Leone; the World Health Organization declared it a Public Health Emergency of International Concern in August 2014.
• Option (a) is wrong: Syria and Jordan were in the news for the civil war and the refugee inflow.
• Option (c) is wrong: the Philippines had earlier reported Reston ebolavirus in macaques, which does not cause human disease, but no human outbreak.
• Option (d) is wrong: the Caribbean states listed had no Ebola cases, and the 2014 outbreak in that region was chikungunya. Elimination route: Ebola virus disease is a zoonosis of Central and West African forest ecosystems with fruit bats as the reservoir, so only the African option can be right.

• Option (d) is correct. H1N1 designates an influenza A subtype named for its surface glycoproteins, haemagglutinin type one and neuraminidase type one; the strain that caused the 2009 pandemic was a reassortant of swine, avian and human influenza genes and was accordingly called swine flu.
• Option (b) is the trap: avian influenza is also an influenza A virus, but the strains of concern carry different subtype designations, principally H5N1 and H7N9, and the H and N numbers are exactly what separate the two diseases.
• Option (a) is wrong: AIDS is caused by the human immunodeficiency virus, a retrovirus with a wholly different genome and mode of transmission.
• Option (c) is wrong: dengue is caused by a flavivirus transmitted by Aedes aegypti. The elimination route is that only two options name influenza at all, and the subtype numbering settles the choice between them. The point worth teaching is that influenza's segmented genome permits reassortment when two strains infect the same host, which is why pigs, susceptible to both avian and human strains, act as a mixing vessel and why new pandemic subtypes emerge from them.

The suffix -ome denotes the complete complement of a class of molecules in a cell or organism: the genome is the full set of DNA, the proteome the full set of proteins, the metabolome the full set of metabolites. The transcriptome, correspondingly, is the full set of RNA transcripts, in the usual usage the messenger RNA molecules expressed by a cell, tissue or organism at a given time. Its scientific interest lies in the fact that unlike the genome, which is essentially fixed, the transcriptome varies with cell type, developmental stage and environmental condition, so it reports which genes are actually being expressed rather than which are merely present. Hence (b).

• Option (a) describes nucleases such as Cas9, ZFNs and TALENs, which belong to genome editing and are not a transcript population at all.
• Option (c) confuses the object with its explanation: a description of a mechanism is not a molecular complement.
• Option (d) describes mutagenesis, which concerns changes to the DNA sequence rather than the RNA output. The elimination route is entirely morphological: only one option names a complete set of molecules, which is what the -ome construction requires, so a candidate who parses the word correctly needs no bioinformatics.

• Statement 1 is correct. Zika virus is a flavivirus transmitted principally by Aedes aegypti, with Aedes albopictus as a secondary vector. Aedes aegypti is the same day biting, container breeding, urban adapted mosquito that transmits dengue, chikungunya and yellow fever, which is why the four diseases share a geography and why vector control measures against one serve against all.
• Statement 2 is correct. Zika is the only mosquito borne flavivirus for which sustained sexual transmission is documented. The virus persists in semen far longer than in blood, and transmission from male to female, female to male and male to male partners has all been recorded, which is why WHO guidance during the epidemic addressed abstinence or protected intercourse and deferral of conception for returning travellers. Both statements standing, the official answer (c) follows. There is no elimination route, but neither statement is obscure, both having been central to the public health messaging of the 2015 and 2016 epidemic. Teaching point worth carrying: the vertical transmission route, from mother to foetus, producing congenital Zika syndrome with microcephaly, is the third route and is the one that made the outbreak a public health emergency.

• Option (c) is correct. Somatic cell nuclear transfer is the procedure in which the nucleus of a differentiated somatic cell of a donor animal is transferred into an oocyte from which the nucleus has been removed. The reconstructed cell is stimulated to divide and the resulting embryo is implanted in a surrogate, yielding an animal genetically identical to the nuclear donor. This is the technique by which Dolly the sheep was produced in 1996, and it is the standard method of reproductive cloning in mammals. Its scientific significance lies in demonstrating that differentiation does not entail irreversible loss of genetic information, since the oocyte cytoplasm can reprogramme an adult nucleus to totipotency.
• Option (a) is wrong because biolarvicides are microbial preparations, chiefly Bacillus thuringiensis israelensis and Bacillus sphaericus, produced by fermentation and unconnected with nuclear transfer.
• Option (b) is wrong because biodegradable plastics such as polyhydroxyalkanoates are made by microbial fermentation or from plant derived monomers.
• Option (d) is wrong and is the most plausible distractor, since disease free stock is produced by meristem tip culture in plants and by specific pathogen free husbandry in animals; nuclear transfer transmits the donor's genome entire, so it reproduces whatever genetic disease the donor carried rather than eliminating it. Governing principle: nuclear transfer copies a genome, and no copying technique can by itself remove disease.

• Statement 1 is incorrect and this is where most candidates go wrong, because the phrase genes of a soil bacterium is correct while the function attributed to them is not. DMH 11 carries the barnase, barstar and bar genes from Bacillus amyloliquefaciens, a soil bacterium, but these do not confer pest resistance. Barnase is a ribonuclease expressed in the tapetum that destroys pollen development and so induces male sterility; barstar is its specific inhibitor, restoring fertility in the hybrid; bar confers tolerance to the herbicide glufosinate and serves as the selectable marker. The pest resistance idea is imported from Bt cotton and brinjal, where the gene is from Bacillus thuringiensis and does confer insect resistance, and the examiner is testing whether the candidate can keep the two bacteria and the two purposes apart.
• Statement 2 is correct and describes exactly what the barnase and barstar system is for. Mustard is a self pollinating crop, which makes controlled crossing laborious and hybrid seed production commercially impractical; engineered male sterility with a fertility restorer supplies the tool that allows hybridisation and the capture of hybrid vigour.
• Statement 3 is incorrect. DMH 11 was developed by the Centre for Genetic Manipulation of Crop Plants at the University of Delhi South Campus under Deepak Pental, not by the Indian Agricultural Research Institute with Punjab Agricultural University. Elimination route: rejecting statement 3 removes options (a), (c) and (d) together and settles the question on one fact.

Hence (b).

• Pair 3 is incorrectly matched and it settles the question on its own. CRISPR Cas9 is a genome editing tool, adapted from a bacterial adaptive immune system in which short repeats store fragments of past viral invaders and the Cas9 nuclease, guided by a matching RNA, cuts double stranded DNA at a chosen sequence. It belongs to molecular biology and has nothing to do with particle physics. Since pair 3 appears in options (a), (c) and (d), rejecting it eliminates all three at once and leaves (b), which is why a candidate who knows only this one fact can answer with confidence.
• Pair 1 is also incorrectly matched, and the two errors are a straight swap. Belle II is a particle physics detector at the SuperKEKB electron positron collider at KEK in Japan, built to study rare decays of B mesons and charge parity violation, and thereby to look for physics beyond the Standard Model.
• Pair 2 is correctly matched. Blockchain is the distributed append only ledger, secured by cryptographic hashing and a consensus mechanism, on which Bitcoin and other cryptocurrencies are built, though the technology has applications well beyond currency, in land records, supply chain provenance and settlement systems.

Hence (b).

• Option (b) is correct as a statement of fact. Artificial functional DNA has been synthesised in laboratories, from the chemical synthesis of a complete bacterial genome in the Mycoplasma work of the Venter group to the construction of synthetic gene circuits and of expanded genetic alphabets.
• Option (c) is correct, and describes something done routinely. The polymerase chain reaction replicates a defined stretch of DNA in a tube, outside any living cell, using a thermostable polymerase, primers and thermal cycling; cell free replication is ordinary laboratory practice.
• Option (d) is correct. Plant and animal cells are cultured and divided in petri dishes as a matter of routine, plant tissue culture and micropropagation on one side and mammalian cell culture on the other.
• Option (a) is the statement the key marks as not correct, and this is where the item is weak. Chromosomes assembled from DNA of more than one species are not beyond reach: yeast artificial chromosomes routinely carry large inserts of foreign DNA and function through mitosis, the Sc2.0 project has synthesised and substituted functional yeast chromosomes, and in 2018 two groups fused the sixteen yeast chromosomes into one and two respectively while retaining viability. A candidate can reach (a) only by elimination, having satisfied himself that the other three are unarguable.

Cas9 is a CRISPR associated endonuclease, an enzyme that cuts double stranded DNA, so (a) is correct. In the CRISPR Cas9 system a guide RNA carrying a sequence complementary to the intended target directs the Cas9 protein to that site in the genome, where it cleaves both strands adjacent to a short protospacer adjacent motif. The cell's own repair machinery then either rejoins the ends imprecisely, disrupting the gene, or, if a template is supplied, repairs the break by homologous recombination, allowing a sequence to be inserted or corrected. The description as molecular scissors captures this cutting function, and the guide RNA is what makes the cutting targeted.

• Option (b) is wrong as stated, although it is the most interesting distractor, since Cas enzymes have since been adapted into diagnostic platforms; Cas9 itself is a nuclease, not a biosensor.
• Option (c) is wrong because Cas9 is a protein of bacterial adaptive immunity, not a plant pest resistance gene, that role belonging to Bt cry genes.
• Option (d) is wrong because Cas9 is not a herbicide; herbicide tolerance in genetically modified crops works by an altered target enzyme such as EPSPS in glyphosate tolerant lines. The governing point is that CRISPR supplies the address and Cas9 supplies the blade.

• Option (b) is the statement that is not correct, and it inverts the true position exactly. A safe and effective recombinant vaccine against hepatitis B has existed since the 1980s and is part of India's Universal Immunisation Programme, given at birth and in the pentavalent schedule. Hepatitis C has no vaccine, the virus's genetic diversity and rapid mutation having defeated development so far, though it has become curable with direct acting antivirals achieving cure rates above ninety five per cent. The statement therefore reverses which of the two has a vaccine.
• Option (a) is correct: hepatitis B is transmitted by blood, by sexual contact and from mother to child, the same routes as HIV, and it is considerably more infectious by those routes.
• Option (c) is correct: the global burden of chronic hepatitis B and C together is of the order of three hundred million people against roughly forty million living with HIV, several times more.
• Option (d) is correct and is the reason the disease is called silent; chronic infection may run for decades without symptoms and present only at the stage of cirrhosis or hepatocellular carcinoma, which is why screening rather than symptom based diagnosis is the public health strategy. The organising fact to carry is the asymmetry: hepatitis B has a vaccine but no cure, hepatitis C has a cure but no vaccine.

Pronuclear transfer is one of the two principal mitochondrial replacement techniques. Both the mother's egg and a donor egg are fertilised, the two pronuclei are removed from the mother's zygote and transferred into the enucleated donor zygote, which retains healthy donor mitochondria. The child inherits nuclear DNA from both parents and mitochondrial DNA from the donor, so maternally transmitted mitochondrial disease is avoided. Hence (d).

• Option (a) is wrong because in vitro fertilisation of an egg by sperm is ordinary IVF or, where a single sperm is injected, intracytoplasmic sperm injection.
• Option (b) is wrong because that describes germline gene therapy directed at spermatogonial cells, an entirely separate line of work.
• Option (c) is wrong because deriving embryos or embryo like structures from stem cells is the field of synthetic embryology, unrelated to pronuclear manipulation.

• Statement 1 is correct, since germline editing of gametes and of the gamete producing cells is technically achievable, whatever the ethical and regulatory bar on its use.
• Statement 2 is correct, since editing at the zygote or early embryo stage is precisely what was done in the 2018 episode in China, and the resulting change is heritable because it is present in every cell.
• Statement 3 is correct, since human induced pluripotent stem cells have been injected into pig embryos to create interspecies chimeras, work directed at eventual organ generation, though the contribution of human cells has remained very low. All three stand, giving (d). Each of options (a), (b) and (c) rests on treating one demonstrated capability as impossible. The general principle to teach here is that the question asks what can be done, not what is permitted.

• Statement 1 is correct. Streptococcus pneumoniae causes not only pneumonia but also bacterial meningitis, septicaemia and otitis media, and the conjugate vaccine protects against the invasive forms as well.
• Statement 2 is correct and is the antimicrobial resistance argument for vaccination. Preventing infection removes the occasion for antibiotic use, and pneumococcus has developed resistance to penicillins and macrolides, so reducing case load directly reduces reliance on drugs that are losing effectiveness.
• Statement 3 is incorrect and is disposed of by the absolute phrasing alone. No vaccine is free of adverse events; injection site reactions, fever and rare hypersensitivity occur with conjugate vaccines as with others. The answer is 1 and 2, giving (b).
• Options (c) and (d) fail on the no side effects claim and (a) drops the resistance argument.

Both statements are correct.

• Statement 1 holds by definition: a recombinant vector vaccine is constructed by inserting the gene encoding an antigen of the target pathogen into the genome of a carrier organism, which is genetic engineering in the strict sense.
• Statement 2 holds because both bacterial and viral vectors are used. Attenuated adenoviruses are the best known viral vectors, used in the Oxford AstraZeneca chimpanzee adenovirus platform, in Sputnik V and in the Johnson and Johnson vaccine, while attenuated bacteria such as Salmonella and BCG have been employed as bacterial vectors, particularly for mucosal delivery. Hence (c). The conceptual point worth drawing out for students is that the vector delivers the genetic instruction and the host's own cells manufacture the antigen, which is what distinguishes this platform from subunit and inactivated vaccines.

• Statement 2 is correct and is the foundational fact: mitochondria are inherited exclusively through the oocyte cytoplasm, because the few paternal mitochondria that enter at fertilisation are selectively degraded, so mitochondrial disease follows a strictly maternal line of transmission.
• Statement 1 is correct and follows from it: mitochondrial replacement therapy transfers the nuclear genome from an affected woman's egg or zygote into a donor egg or zygote whose own nucleus has been removed but whose mitochondria are healthy. This can be done before fertilisation by maternal spindle transfer, or after fertilisation by pronuclear transfer, so the phrase either before or after in vitro fertilization is accurate and is the precise point being tested. Hence (c). The technique is the origin of the loose journalistic phrase three parent baby, and the resulting child carries nuclear DNA from two parents and mitochondrial DNA from a third.

• Statement 1 is incorrect on both limbs, which is unusual and makes it easier once the biology is secure. Adenoviruses have double stranded DNA genomes, not single stranded. Retroviruses have single stranded RNA genomes, not double stranded DNA, and their defining feature is reverse transcriptase, which copies that RNA into DNA for integration into the host chromosome, the very reversal of the central dogma from which the group takes its name.
• Statement 2 is correct: adenoviruses are among the agents of the common cold, alongside rhinoviruses and coronaviruses, and AIDS is caused by HIV, a retrovirus of the lentivirus genus. Hence (b). A candidate who remembers only that retroviruses are RNA viruses can reject statement 1 outright and reach the answer.

ACE2 is angiotensin converting enzyme 2, a membrane bound enzyme of the renin angiotensin system present on cells of the respiratory epithelium, intestine, heart and kidney. It became globally significant because the spike protein of SARS-CoV-2 binds ACE2 to gain entry into host cells, which explains both the tissue distribution of COVID-19 damage and the design of vaccines and therapeutics targeting that interaction.

• Option (d) is therefore correct.
• Option (a) is wrong because transgenic plant genes are designated cry, bar and similar.
• Option (b) is wrong because India's navigation system is NavIC, built on the IRNSS constellation.
• Option (c) is wrong because radio collars involve VHF and satellite telemetry, not enzyme nomenclature.

Hence (d).

A biofilm is a community of microorganisms adhering to a surface and embedded in a self produced matrix of extracellular polymeric substances, and the three statements describe its best documented properties.

• Statement 1 is correct: catheters, prosthetic joints, heart valves and other indwelling devices are classic substrates, and device associated biofilm infection is a major clinical problem precisely because the implant offers an abiotic surface shielded from host defences.
• Statement 2 is correct: biofilms form readily on food contact surfaces and processing equipment, which is why sanitation regimes in food plants target them specifically.
• Statement 3 is correct and is the property that matters most clinically. Cells within a biofilm tolerate antibiotic concentrations orders of magnitude above those that kill the same organisms in free floating culture, because the matrix impedes penetration, the interior cells are metabolically slow and so escape agents that act on growing cells, and persister subpopulations survive treatment. All three holding, (d) is correct; options (a), (b) and (c) each omit a well established property.

• Statement 1 is incorrect. Covishield, manufactured by the Serum Institute of India under licence from Oxford and AstraZeneca, is a replication deficient chimpanzee adenovirus vector carrying the gene for the spike protein. It is not an mRNA vaccine; the mRNA platform in the COVID-19 context belongs to the Pfizer BioNTech and Moderna products, neither of which was made by the Serum Institute.
• Statement 2 is correct. Sputnik V is a viral vector vaccine and is distinctive in using two different adenovirus vectors, Ad26 for the first dose and Ad5 for the second, a heterologous prime boost designed to avoid the anti vector immunity that would blunt a repeat dose of the same vector.
• Statement 3 is correct. COVAXIN, developed by Bharat Biotech with the Indian Council of Medical Research and the National Institute of Virology, is a whole virion inactivated vaccine, in which the virus is killed and presented with an adjuvant.
• Statements 2 and 3 holding, (b) is correct, and options (a), (c) and (d) each accept the platform error in statement 1.

DNA barcoding identifies an organism by sequencing a short, standardised region of its genome and matching that sequence against a reference library, the mitochondrial cytochrome c oxidase I gene serving for animals and chloroplast regions such as rbcL and matK for plants. The method answers the question of what an organism is, and its capabilities follow from that.

• Statement 1 is incorrect, since the barcode sequence is a property of the species and does not change as an individual ages; age is estimated by other means altogether, growth rings, otoliths, skeletal or dental features, or in some contexts telomere length or epigenetic clocks, none of which is barcoding.
• Statement 2 is correct and is the method's central application, resolving cryptic species and morphologically indistinguishable specimens, and identifying material such as larvae, fragments or processed parts that cannot be identified by appearance.
• Statement 3 is correct and follows directly: because a barcode can be recovered from fragmentary tissue, the technique is used in food authentication to detect substituted or adulterated ingredients and undeclared species in processed products.
• Statements 2 and 3 holding, (d) is correct; options (a) and (c) accept the age determination claim, and (b) drops the method's principal use.

The term is built from its two parts. Metagenomics is the sequencing of genetic material recovered directly from an environmental sample rather than from a cultured or captured organism, and aerial specifies air as the medium. Aerial metagenomics therefore means filtering air and sequencing the environmental DNA it carries in shed skin, hair, spores, pollen and droplets, which allows an inventory of species present in a habitat without observing or trapping any of them.

• Option (b) confuses aerial with avian, a trap resting on the word association with birds.
• Option (c) describes remote biological sampling of blood, which involves neither air as a medium nor metagenomic sequencing.
• Option (d) describes drone assisted field sampling, which uses aerial platforms but collects conventional physical samples from land and water rather than DNA from the air itself.

Microsatellites, also called short tandem repeats, are stretches of DNA in which a motif of one to six base pairs is repeated in tandem. They mutate rapidly by replication slippage, so the number of repeats at a locus varies greatly between individuals, and they are co dominant and distributed throughout the genome. That high polymorphism makes them standard markers for individual identification in forensic DNA profiling, for parentage and population genetics, and for inferring relatedness and divergence among populations and closely related species, which is what (a) describes.

• Option (b) concerns growth factors and differentiation signals in stem cell biology, unrelated to repeat markers.
• Option (c) concerns tissue culture and vegetative propagation techniques.
• Option (d) concerns clinical trial methodology and pharmacology.

Hence (a).

• Statement I is correct: monoclonal antibodies are laboratory-produced immunoglobulin proteins, classically generated by hybridoma technology in which an antibody-producing B cell is fused with a myeloma cell to create an immortal clone secreting a single antibody specificity, and now increasingly by recombinant and humanised methods. The term monoclonal captures exactly this, that all molecules derive from one clone and are therefore identical, in contrast to the polyclonal mixture produced by a natural immune response.
• Statement II is correct: their therapeutic action rests on binding a chosen antigen with high specificity, which can neutralise a pathogen directly by blocking entry, or recruit immune effector functions such as complement activation and antibody-dependent cellular cytotoxicity.
• Statement III is correct: the monoclonal antibody m102.4 has been used against Nipah virus, including on a compassionate basis during outbreaks in Kerala, and monoclonals have also been deployed against Ebola, respiratory syncytial virus and, during the pandemic, SARS-CoV-2. All three hold, giving (d).
• Options (a), (b) and (c) each drop one accurate statement, with no error present in any of the three to justify exclusion.

• Statement 1 is correct and is the definition of the field, since gene therapy either supplies a working copy of a defective gene, silences a harmful one, or edits the sequence at a specific site so that the underlying genetic cause rather than the symptom is addressed.
• Statement 2 is correct, since delivery is the central engineering problem and the two dominant answers are viral vectors, chiefly adeno associated virus and lentivirus stripped of their capacity to replicate, and lipid nanoparticles, which encapsulate nucleic acid in an ionisable lipid shell and are the technology familiar from messenger RNA vaccines.
• Statement 3 is incorrect and is the eliminator. The whole point of the technology is that intervention is targeted, at one gene or one locus, and altering an entire genome of three billion base pairs is neither the aim nor within reach, and would be catastrophic if attempted. Hence 1 and 2 and (c) is correct. (a) drops the well established delivery methods, and (b) and (d) accept a claim that contradicts the targeted nature of the therapy.

• Statement 1 is incorrect and is the eliminator on chronology alone. The Human Genome Project was an international effort that ran from 1990 and was declared complete in 2003, producing a single composite reference sequence, whereas GenomeIndia was launched in 2020 as an independent Indian initiative, so a project begun seventeen years after another ended cannot be a part of it.
• Statement 2 is correct, since GenomeIndia is funded and coordinated by the Department of Biotechnology and executed through a consortium of about twenty Indian institutions led by the Indian Institute of Science.
• Statement 3 is correct, and it is also the reason the project exists. A single reference genome cannot represent a population of the size and endogamous structure of India's, so the aim is a catalogue of variation across diverse population groups, ten thousand whole genomes having been sequenced in the first phase, to support disease association studies and precision medicine for Indian populations.

Hence 2 and 3 and (b) is correct, while (a), (c) and (d) admit the false link to the Human Genome Project.