UPSC CSE Prelims
Biotechnology 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:

Statement 1 — Correct. Genetic medicines (gene therapy and gene editing) treat diseases at their root cause by introducing, removing, or changing genetic material to correct or compensate for faulty/missing genes responsible for a disease.

Statement 2 — Correct. Genetic material cannot be injected directly — it requires a vector (carrier):

Statement 3 — Incorrect. Genetic medicines do NOT alter the entire DNA sequence. The human genome has ~3 billion base pairs and 20,000+ genes. Gene therapies are highly precise — targeting only specific localized sequences or single genes while leaving the vast majority of native DNA completely unchanged.

Key Trick: Statement 3 uses the word "entire" — a classic UPSC exaggeration trap. Precision, not wholesale alteration, is the hallmark of genetic medicine.

Detailed Explanation:

All three statements are incorrect because viruses are found in diverse environments, can infect bacteria, and can manipulate host cell functions.

• Statement I is Incorrect: Viruses are extremely abundant in oceans and play an important role in marine ecosystems.

• Statement II is Incorrect: Certain viruses called bacteriophages specifically infect bacteria.

• Statement III is Incorrect: Viruses can alter the host cell's transcriptional machinery to produce viral proteins and replicate themselves.

• Therefore, none of the statements are correct, making Option D the correct answer.

Statement-wise Analysis

Viruses

What are Viruses?

Viruses are microscopic infectious agents that can reproduce only inside living host cells.

Important Facts

• Found in soil, air, freshwater, oceans, and living organisms.

• Cannot reproduce independently.

• Use host cell machinery to make new viruses.

• Can infect animals, plants, fungi, and bacteria.

Bacteriophages

• Viruses that infect bacteria.

• Among the most abundant biological entities on Earth.

• Widely used in biotechnology and phage therapy research.

How Viruses Affect Host Cells

Viruses can:

• Alter gene expression.

• Hijack cellular machinery.

• Suppress immune responses.

• Change transcription and protein synthesis pathways.

Detailed Explanation:

Correct Answer: ✅ 1 Only (Option A)

Hydrogels are three-dimensional polymer networks that can absorb and retain large amounts of water. Their biocompatibility and controlled swelling properties make them highly useful in medical applications.

✅ Statement I is Correct: Hydrogels are widely used in controlled drug delivery because they can absorb water and release medicines gradually at a desired rate.

❌ Statement II is Incorrect: Mobile air-conditioning systems use refrigerants, compressors, and heat exchangers. Hydrogels are not standard components in these cooling systems.

❌ Statement III is Incorrect: Industrial lubricants are generally oil-based or synthetic formulations. Hydrogels do not possess the required lubrication properties for industrial use.

Short Notes: Hydrogels

• Hydrogels are water-absorbing polymer networks capable of holding large amounts of water.

• They can contain up to 90–99% water while maintaining their structure.

• Widely used in controlled drug delivery systems.

• Used in contact lenses, wound dressings, and tissue engineering.

• Most hydrogels are biocompatible and non-toxic.

• They respond to changes in pH, temperature, and moisture.

• Hydrogels are important materials in biomedical engineering and regenerative medicine.

Detailed Explanation:

Answer: Option 3 — All three

All three statements are correct as extremophiles (microorganisms adapted to extreme conditions) can survive and thrive in environments that would be lethal to most life forms. These include extreme temperatures both above boiling and below freezing, as well as highly acidic conditions.

✅ Statement 1 – Correct: Hyperthermophiles like Pyrolobus fumarii can thrive in temperatures above 100°C (boiling point of water), often found in hydrothermal vents at temperatures up to 113°C.

✅ Statement 2 – Correct: Psychrophiles (cryophiles) are cold-loving microorganisms capable of growth in temperatures ranging from -20°C to +10°C, well below the freezing point of water (0°C).

✅ Statement 3 – Correct: Acidophiles such as Picrophilus oshimae thrive in highly acidic environments with pH below 3, with some species surviving at pH levels near 0.

📝 Short Notes: Extremophiles

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 1 — Studying the evolutionary relationships among various species of fauna

Microsatellite DNA, also known as Short Tandem Repeats (STRs), are highly polymorphic DNA sequences that show significant variation among individuals and populations. These variations make them excellent genetic markers for studying evolutionary relationships, population genetics, and phylogenetic studies among different species of fauna. The high mutation rate and variability in the number of repeated sequences allow researchers to trace genetic lineages and understand evolutionary divergence patterns.

📝 Short Notes: Microsatellite DNA (Short Tandem Repeats)

• Definition: Microsatellites are short repetitive DNA sequences (typically 1-6 base pairs) repeated in tandem arrays throughout the genome.
• Polymorphism: Highly variable in repeat number between individuals, making them useful genetic markers for identification and diversity studies.
• Applications in Evolutionary Biology: Used to study genetic diversity, population structure, gene flow, and phylogenetic relationships among species.
• Other Applications: DNA fingerprinting, paternity testing, forensic analysis, conservation genetics, and breeding programs.
• Advantages: Co-dominant inheritance, high mutation rates, abundance in genomes, and ease of amplification using PCR.
• Not Related to: Stem cell transformation, clonal propagation techniques, or direct drug efficacy testing (these involve different molecular techniques).

Detailed Explanation:

Answer: Option 4 — All four

All four statements about mushroom properties are scientifically accurate. Mushrooms exhibit a remarkable diversity of biological properties that have been documented and utilized across medicinal, recreational, agricultural, and ecological contexts.

✅ Statement 1 – Correct: Medicinal mushrooms like Reishi (Ganoderma lucidum), Turkey Tail (Trametes versicolor), and Lion's Mane (Hericium erinaceus) contain bioactive compounds with immune-modulating, anti-inflammatory, and neuroprotective properties.

✅ Statement 2 – Correct: Psychoactive mushrooms containing psilocybin (such as Psilocybe cubensis) produce hallucinogenic effects and are being researched for therapeutic applications in treating depression and PTSD.

✅ Statement 3 – Correct: Insecticidal mushrooms like Metarhizium anisopliae and Beauveria bassiana produce compounds toxic to insects and are used as biological pest control agents in agriculture.

✅ Statement 4 – Correct: Bioluminescent mushrooms such as Mycena chlorophos and Panellus stipticus produce light through enzymatic reactions involving luciferin and luciferase, creating a natural glow in dark forest environments.

📝 Short Notes: Properties of Mushrooms

Detailed Explanation:

Answer: Option 3 — 1 and 2

Gucchi (Morchella esculenta) is a rare and expensive wild mushroom fungus found in the Himalayan regions. It grows naturally in temperate forest areas following snowmelt but cannot be commercially cultivated, making statements 1 and 2 correct while statement 3 is incorrect.

✅ Statement 1 – Correct: Gucchi is a fungus (Morchella esculenta) belonging to the Morchellaceae family, known for its distinctive honeycomb-like appearance and prized culinary value.

✅ Statement 2 – Correct: It grows naturally in the temperate conifer forest areas of the Himalayas, particularly in Jammu and Kashmir, Himachal Pradesh, and Uttarakhand during spring after snowmelt.

❌ Statement 3 – Incorrect: Gucchi mushrooms cannot be commercially cultivated due to their complex mycorrhizal associations with trees; they are wild-harvested, and they primarily grow in the Western Himalayas, not the north-eastern foothills.

📝 Short Notes: Gucchi (Morchella Mushroom)

• Scientific Name: Morchella esculenta, belonging to family Morchellaceae
• Appearance: Distinctive honeycomb or sponge-like cap structure, light brown to dark brown color
• Habitat: Temperate conifer forests of Western Himalayas (J&K, Himachal Pradesh, Uttarakhand) at altitudes of 2,500-3,500 meters
• Season: Grows in spring (March-May) following snowmelt in moist, shaded forest floors
• Economic Value: One of the most expensive mushrooms globally, fetching ₹10,000-30,000 per kg; major export item
• Cultivation Status: Cannot be commercially cultivated due to complex symbiotic relationship with tree roots; only wild-harvested by local communities
• Nutritional Value: Rich in protein, vitamins (especially Vitamin D), minerals, and antioxidants
• Conservation Concern: Over-harvesting threatens wild populations; sustainable harvesting practices needed

Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

All three statements about biofilms are correct. Biofilms are complex microbial communities encased in a self-produced protective matrix that can form on various surfaces, including medical implants, food processing equipment, and biological tissues, exhibiting significant antibiotic resistance.

✅ Statement 1 – Correct: Biofilms readily form on medical implants like catheters, heart valves, and artificial joints within human tissues, leading to chronic infections that are difficult to treat.

✅ Statement 2 – Correct: Biofilms commonly form on food and food processing surfaces, contaminating food products and contributing to spoilage while being resistant to standard cleaning methods.

✅ Statement 3 – Correct: Bacteria within biofilms exhibit 10-1000 times greater antibiotic resistance than planktonic (free-floating) bacteria due to the protective matrix barrier, altered metabolic states, and horizontal gene transfer mechanisms.

📝 Short Notes: Biofilms

• Definition: Biofilms are structured communities of microorganisms encased in a self-produced extracellular polymeric substance (EPS) matrix, adhering to surfaces.
• Medical Implications: Responsible for 65-80% of all microbial infections in humans; form on indwelling medical devices, teeth (dental plaque), and in chronic wounds.
• Resistance Mechanisms: EPS matrix acts as a barrier to antimicrobials; slow growth rate in biofilms reduces antibiotic efficacy; persister cells survive treatment; gene transfer promotes resistance spread.
• Industrial Impact: Contaminate water pipes, ship hulls (biofouling), heat exchangers, and food processing equipment; cause economic losses and efficiency reduction.
• Food Safety: Biofilms in food industry harbor pathogens like Listeria, Salmonella, and E. coli; resistant to standard sanitization procedures.
• Control Strategies: Include mechanical removal, enzymatic disruption of EPS, quorum sensing inhibitors, and combination antimicrobial therapies.

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 — 1 and 3

This question tests knowledge about probiotics, which are live microorganisms beneficial for gut health. Statements 1 and 3 are correct as probiotics include both bacteria and yeast, and certain strains help digest lactose (milk sugar).

✅ Statement 1 – Correct: Probiotics consist of both bacteria (like Lactobacillus, Bifidobacterium) and yeast (like Saccharomyces boulardii).

❌ Statement 2 – Incorrect: Probiotic organisms naturally occur in our gut as part of the normal gut microbiome; probiotics supplement these beneficial microbes.

✅ Statement 3 – Correct: Some probiotic strains produce lactase enzyme, which helps break down lactose (milk sugar), aiding digestion especially in lactose-intolerant individuals.

📝 Short Notes: Probiotics

• Definition: Live microorganisms that provide health benefits when consumed in adequate amounts, particularly for gut health.
• Common Types: Bacteria (Lactobacillus, Bifidobacterium, Streptococcus thermophilus) and Yeast (Saccharomyces boulardii).
• Natural Sources: Yogurt, kefir, sauerkraut, kimchi, tempeh, miso, pickles, and other fermented foods.
• Benefits: Improve digestive health, enhance immune function, aid lactose digestion, synthesize vitamins (B and K), prevent diarrhea and constipation.
• Gut Microbiome: Human gut naturally contains trillions of microorganisms; probiotics supplement beneficial strains already present.
• vs Prebiotics: Probiotics are live organisms; prebiotics are non-digestible food components that feed beneficial gut bacteria.

Detailed Explanation:

Answer: Option 1 — 1 and 2 Only

Bacteria and fungi can be cultured in artificial/synthetic media as they possess complete cellular machinery for independent growth and reproduction. Viruses, being obligate intracellular parasites, lack cellular machinery and can only replicate inside living host cells, making them incapable of growth in synthetic media.

✅ Statement 1 (Bacteria) – Correct: Bacteria can be cultured in various artificial media like nutrient agar, nutrient broth, and other specialized media as they are self-sufficient organisms with complete metabolic machinery.

✅ Statement 2 (Fungi) – Correct: Fungi can be cultured in artificial media such as Potato Dextrose Agar (PDA), Sabouraud Dextrose Agar, and Czapek Dox Agar, as they can independently utilize nutrients for growth.

❌ Statement 3 (Virus) – Incorrect: Viruses cannot be cultured in artificial/synthetic media as they are acellular and require living host cells (embryonated eggs, cell cultures, or living organisms) for replication.

📝 Short Notes: Microorganism Cultivation Methods

• Artificial Media: Chemically defined or complex media prepared in laboratory without living cells
• Bacterial Culture: Can grow on solid (agar plates) or liquid (broth) media at specific temperature and pH
• Fungal Culture: Require slightly acidic pH and longer incubation periods compared to bacteria
• Viral Culture: Requires tissue culture, embryonated chicken eggs, or experimental animals
• Key Difference: Viruses are acellular and depend entirely on host cell ribosomes, enzymes, and nucleotides for replication

Detailed Explanation:

Answer: Option 2 — developing genetically modified crop plants.

Bollgard I and Bollgard II are biotechnology products developed for creating genetically modified (GM) cotton plants with insect resistance. These technologies use genes from Bacillus thuringiensis (Bt) bacteria to produce insecticidal proteins that protect cotton plants from bollworm and other lepidopteran pests, thereby reducing the need for chemical pesticides.

📝 Short Notes: Bt Cotton Technologies

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