UPSC CSE Prelims
Genetic Engineering Previous Year Questions (PYQs)

Detailed Explanation:

Statement 1 is incorrect because the GenomeIndia Project is an independent Indian initiative and not a part of the Human Genome Project.

Statements 2 and 3 are correct. The project is funded by the Department of Biotechnology (DBT) and aims to create a comprehensive catalogue of the genetic diversity of the Indian population.

Therefore, Option B (2 and 3 only) is correct.

The GenomeIndia Project was launched in 2020 to sequence genomes from diverse Indian communities. It helps researchers understand genetic variations, improve disease diagnosis, develop personalized medicine, and strengthen biomedical research in India.

Detailed Explanation:

Answer: Option 1 — Collecting DNA samples from air in a habitat at one go

Aerial metagenomics is a cutting-edge technique that involves collecting environmental DNA (e-DNA) directly from the air using specialized filters or vacuum systems. Organisms constantly shed genetic material into their surroundings through breath, skin cells, fur, pollen, spores, and other biological particles, which can be captured from air samples. This method allows researchers to simultaneously identify and monitor multiple species—including animals, plants, fungi, and microorganisms—in a specific habitat without physical intrusion, making it a powerful non-invasive tool for biodiversity assessment.

📝 Short Notes: Metagenomics & Environmental DNA

• Metagenomics: The study of genetic material recovered directly from environmental samples (soil, water, air) without isolating individual organisms in laboratory cultures.
• Environmental DNA (e-DNA): Genetic material shed by organisms into their environment through skin cells, mucus, feces, gametes, and other biological materials.
• Aerial Metagenomics: Specifically focuses on capturing DNA from airborne particles using air filtration systems to assess biodiversity in a habitat.
• Applications: Non-invasive biodiversity monitoring, detecting rare or elusive species, tracking disease vectors, and studying ecosystem health.
• Advantages: Simultaneous detection of multiple taxa, no need for visual observation or physical capture, time and cost-efficient for large-scale surveys.

Detailed Explanation:

Answer: Option 4 — 2 and 3

DNA barcoding is a molecular technique that uses short, standardized gene sequences to identify species. It is particularly effective for distinguishing morphologically similar species and detecting species composition in processed materials, but it cannot determine the age of organisms.

❌ Statement 1 – Incorrect: DNA barcoding identifies species based on genetic sequences but cannot assess the age of a plant or animal, as age determination requires other methods like dendrochronology or carbon dating.

✅ Statement 2 – Correct: DNA barcoding excels at distinguishing among species that look morphologically similar by comparing their unique genetic barcodes (typically COI gene in animals, rbcL or matK in plants).

✅ Statement 3 – Correct: DNA barcoding is extensively used in food safety to identify undeclared or undesirable animal/plant materials in processed foods, helping detect food adulteration and mislabeling.

📝 Short Notes: DNA Barcoding

• Definition: A molecular tool that uses short, standardized DNA sequences to rapidly identify species
• Gene Markers: COI (Cytochrome C Oxidase I) for animals; rbcL, matK, ITS for plants
• Applications: Species identification, biodiversity assessment, food authentication, detection of illegal wildlife trade, identification of medicinal plants
• Advantages: Works with small tissue samples, identifies cryptic species, useful for immature/damaged specimens
• Limitations: Cannot determine age, recent speciation may show similar sequences, requires reference database
• Global Initiative: International Barcode of Life (iBOL) project maintains comprehensive DNA barcode libraries

Detailed Explanation:

Answer: Option 3 — Both 1 and 2

Mitochondrial replacement therapy (MRT) is a reproductive technique designed to prevent the transmission of mitochondrial diseases from mother to child by replacing defective mitochondria with healthy donor mitochondria, either before or after in vitro fertilization. Mitochondrial DNA is inherited exclusively through the maternal line, as mitochondria in sperm are typically destroyed after fertilization, making it impossible for a child to inherit mitochondrial diseases from the father.

✅ Statement 1 – Correct: MRT can be performed either before fertilization (using maternal spindle transfer) or after fertilization (using pronuclear transfer) to prevent mitochondrial disease transmission.
✅ Statement 2 – Correct: Mitochondrial DNA is inherited entirely from the mother, as only the egg contributes mitochondria to the embryo.

📝 Short Notes: Mitochondrial Inheritance and Replacement Therapy

Detailed Explanation:

Answer: Option 4 — prevention of mitochondrial diseases in offspring

Pronuclear transfer is a mitochondrial replacement therapy technique used to prevent the transmission of mitochondrial diseases from mother to child. The technique involves transferring the pronuclei (nuclei from both egg and sperm before fusion) from a fertilized egg with defective mitochondria into a donor egg with healthy mitochondria but whose own pronuclei have been removed. This allows the child to inherit nuclear DNA from the biological parents while receiving healthy mitochondrial DNA from the donor, thereby preventing mitochondrial diseases.

📝 Short Notes: Mitochondrial Replacement Therapy

• Mitochondria: Cellular organelles with their own DNA (mtDNA) separate from nuclear DNA; mutations in mtDNA cause inherited mitochondrial diseases affecting muscles, nerves, brain, and other organs.
• Pronuclear Transfer (PNT): One of two main mitochondrial replacement techniques; involves transferring pronuclei from fertilized egg to donor egg with healthy mitochondria.
• Maternal Spindle Transfer (MST): Alternative technique performed before fertilization; nuclear DNA from mother's egg transferred to donor egg with healthy mitochondria.
• Three-Parent Baby: Resulting child has nuclear DNA from biological parents and mitochondrial DNA from donor (contributes <0.1% of total DNA).
• Ethical and Legal Status: First approved in UK (2015); performed in limited countries; raises ethical debates about genetic modification and germline editing.
• Applications: Prevents severe mitochondrial diseases like Leigh syndrome, MELAS, and Kearns-Sayre syndrome from being passed to offspring.

Detailed Explanation:

The transcriptome refers to the complete set of RNA transcripts (especially mRNA molecules) produced by the genome of an organism under specific circumstances or in a specific cell.

Unlike the static genome, the transcriptome is dynamic and reflects which genes are actively being expressed at any given time, making it crucial for understanding gene regulation, cellular functions, and responses to environmental stimuli.

Detailed Explanation:

❌ Statement 1 – Incorrect: Budding and grafting are traditional vegetative propagation techniques that multiply plants asexually without altering DNA; no recombinant DNA technology is used, so they do not create transgenic crops.

✅ Statement 2 – Correct: Cytoplasmic male sterility (CMS) can be manipulated through genetic engineering to introduce or transfer sterility genes into crops, creating transgenic lines for hybrid seed production.

✅ Statement 3 – Correct: Gene silencing (RNA interference/RNAi) uses engineered genetic constructs to suppress specific gene expression in plants, making it a key technique for developing transgenic crops with desired traits.

Detailed Explanation:

✅ Statement 1 – Correct: Recombinant DNA technology enables gene transfer across different plant species to introduce desirable traits like disease resistance.

✅ Statement 2 – Correct: Animal genes can be transferred to plants; for example, antifreeze protein genes from cold-water fish have been introduced into tomatoes and strawberries for frost tolerance.

✅ Statement 3 – Correct: Genes from microorganisms are routinely transferred to higher organisms; Bacillus thuringiensis (Bt) genes from soil bacteria are transferred to crops like cotton and corn for pest resistance.

Detailed Explanation:

❌ Statement 1 – Incorrect: Stem cells are found in all multicellular organisms, not just mammals—including plants, vertebrates, and invertebrates.

✅ Statement 2 – Correct: Stem cells are used for drug screening by generating specific cell types to test safety and efficacy of new pharmaceutical compounds before clinical trials.

✅ Statement 3 – Correct: Stem cells have applications in regenerative medicine including bone marrow transplants for blood disorders and tissue/organ repair.

Detailed Explanation:

✅ Statement 1 – Correct: Drought-resistant crops like drought-tolerant maize and water-efficient rice have been developed by introducing genes that enable water conservation and stress tolerance.

✅ Statement 2 – Correct: Golden Rice (fortified with Vitamin A), iron-biofortified crops, and protein-enhanced legumes demonstrate increased nutritive value through genetic engineering.

❌ Statement 3 – Incorrect: Growing plants in spaceships and space stations relies on controlled environment agriculture, not genetic engineering; NASA experiments use conventional plant varieties adapted through breeding, not GM technology.

✅ Statement 4 – Correct: Flavr Savr tomato (first GM food approved in 1994) and other crops have been engineered with delayed ripening genes to increase shelf life and reduce post-harvest losses.