Biotechnology: UPSC Previous Year Questions (Science and Technology)

Explanation

Statement I is correct: Monoclonal antibodies are laboratory-produced proteins created using hybridoma technology (developed in 1975) or recombinant DNA techniques, where B cells are fused with myeloma cells to produce identical antibodies targeting a specific antigen. This ensures high specificity for one antigen epitope.

Statement II is correct:

Monoclonal antibodies (mAbs) bind to specific antigens via their Fab (fragment antigen-binding) region, triggering immunological responses. The Fc (fragment crystallizable) region recruits immune cells (e.g., macrophages, NK cells) and activates the complement system, enhancing pathogen clearance and T-cell activation. While mAbs provide passive immunity and do not induce long-term immune memory, their ability to trigger ADCC, CDC, and phagocytosis constitutes immunological stimulation by engaging existing immune mechanisms.

Statement III is correct:

Therapeutic Use: Monoclonal antibodies are used to treat viral infections, including Nipah virus (NiV), a zoonotic paramyxovirus with a 40-75% fatality rate. Specific mAbs like m102.4, hu1F5, NiV41, and NiV42 target NiV G and F glycoproteins, neutralizing viral entry.

Explanation

The membrane bioreactor (MBR) has emerged as an efficient compact technology for municipal and industrial wastewater treatment. These systems have the advantage of combining a suspended growth biological reactor with solids removal via filtration. Membranes in MBR systems are designed to function efficiently in compact spaces while effectively removing contaminants like nitrogen, phosphorus, bacteria, biochemical oxygen demand (BOD), and total suspended solids (TSS). The filtration process supports higher biomass concentrations, enabling the use of smaller bioreactors. The effluent from MBRs contains low concentrations of bacteria, total suspended solids (TSS), and biochemical oxygen demand (BOD). This facilitates high-level disinfection. Effluents are readily discharged to surface streams or can be sold for reuse, such as irrigation.

Explanation

Nitric oxide is a naturally synthesized molecule in the human body that plays a crucial role in vasodilation, which is the widening of blood vessels. It is produced by endothelial cells lining the blood vessels through the action of the enzyme nitric oxide synthase (NOS) on L-arginine. Nitric oxide diffuses into the smooth muscle cells of blood vessels. It activates an enzyme called guanylate cyclase, which increases the production of cyclic guanosine monophosphate (cGMP). cGMP causes the relaxation of smooth muscles, leading to the widening of blood vessels (vasodilation). By relaxing the smooth muscles of blood vessels, nitric oxide increases blood flow and helps regulate blood pressure. It also has important functions in immune response and neurotransmission.

Explanation

Metagenomics delves into the study of microbes within their native habitats. "Aerial metagenomics" entails collecting air samples from a specific setting to capture the genetic material (DNA) of various microorganisms, encompassing bacteria, viruses, fungi, and other microscopic life forms.

Explanation

Microsatellite DNA, alternatively known as short tandem repeats (STRs), represents a genetic marker characterised by repetitive sequences of DNA. Highly polymorphic, microsatellites exhibit varying lengths attributed to discrepancies in the number of repeat units. By scrutinising the discrepancies in microsatellite DNA sequences within individuals or populations, scientists can evaluate genetic diversity, population structure, and evolutionary links both within species and across different species.

Explanation

RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules. This technology has gained immense popularity because of its potential in gene silencing, therapeutic applications, and agricultural improvements.

Statement 1 is correct: RNAi technology is primarily used to silence specific genes by targeting the messenger RNA (mRNA) produced by a gene. When RNAi molecules (small interfering RNA or siRNA) are introduced into cells, they bind to complementary mRNA, causing its degradation and preventing protein translation. This has vast potential in treating genetic diseases caused by overactive or malfunctioning genes. Gene therapies targeting diseases like amyotrophic lateral sclerosis (ALS) and Huntington’s disease use RNAi to silence mutant genes causing the disease.

Statement 2 is correct: Numerous studies have demonstrated that RNAi can provide a more specific approach to inhibit tumor growth by targeting cancer-related genes (i.e., oncogene). Researchers are investigating RNAi-based therapeutics to target these oncogenes selectively.

Statement 3 is incorrect: Hormone Replacement Therapy (HRT) is a medical treatment that involves replacing hormones in the body to alleviate symptoms related to hormonal imbalances or deficiencies. Though RNAi has been investigated as a potential tool for regulating hormone-related genes, it is not a primary mechanism of action for HRT.

Statement 4 is correct: RNAi is increasingly applied in agriculture to create genetically modified crops that are resistant to viral infections. By silencing the genes of the virus or the plant’s genes that are required for viral replication, RNAi-based technologies offer a potential solution to combat viral pathogens that affect crops. Crops like papaya and potatoes have been genetically engineered using RNAi technology to confer resistance to viruses such as the papaya ringspot virus and potato virus Y.

Explanation

Somatic Cell Nuclear Transfer (SCNT) is a technique used in cloning, where the nucleus of a somatic cell (any cell of the body other than a sperm or egg cell) is transferred into an egg cell whose nucleus has been removed. The SCNT-derived blastocyst used in reproductive cloning is implanted into the uterus of a surrogate mother, where it develops into a foetus and is carried to term.

Option (c) is correct: SCNT is used in reproductive cloning of animals. This technique allows the creation of genetically identical animals, such as Dolly the sheep, the first mammal cloned from an adult somatic cell in 1996. The process involves taking the nucleus from a somatic cell (e.g., skin cell) of an adult animal and transferring it into an enucleated egg cell. The egg, now containing the somatic cell nucleus, begins to divide and develop into an embryo. This embryo can then be implanted into a surrogate mother to produce an offspring that is genetically identical to the donor animal. Fig.: Some classic examples of successful applications of biotechnology

Explanation

Genome sequencing is the process of determining the complete DNA sequence of an organism’s genome by identifying the precise order of nucleotides--adenine (A), thymine (T), cytosine (C), and guanine (G)--that make up its genetic material. This comprehensive analysis provides critical insights into an organism’s genetic information, including variations, mutations, and functional elements such as genes and regulatory regions.

Statement 1 is correct: Genome sequencing can be used to identify specific genes or genetic markers in crops that confer resistance to diseases or tolerance to environmental stresses like drought. This allows plant breeders to select plants with these beneficial traits and accelerate crop improvement.

Statement 2 is correct: Genome sequencing speeds up the breeding process. Instead of relying on traditional trial-and-error methods to cross plants, scientists can use genome information to make more precise genetic selections.

Statement 3 is correct: Genome sequencing can also help researchers understand how crops interact with pathogens (like bacteria, fungi, and viruses). By mapping the genomes of both the host plant and the pathogen, researchers can identify the genes involved in defense mechanisms and the pathogen’s strategies for evading these defenses.

Explanation

Viruses are obligate intracellular parasites, meaning they require a host cell to replicate. They can infect bacteria, fungi, plants, animals, and other viruses. Viruses that infect bacteria are called bacteriophages (or simply phages). These viruses play a crucial role in regulating bacterial populations. Phages attach to bacterial cells, inject their genetic material, and hijack the bacterial machinery to replicate themselves. This process often leads to the destruction (lysis) of the bacterial cell. Viruses that infect fungi are called mycoviruses (Mycophages). They do not have an extracellular phase (i.e., they lack the ability to move outside fungal cells). They are linked to plant diseases because they weaken fungi that help plant growth. Cryphonectria hypovirus 1 (CHV1) infects chestnut blight fungus (Cryphonectria parasitica). Plant viruses are well-known pathogens that cause significant economic losses in agriculture such as the Tobacco Mosaic Virus (TMV), Potato Virus Y (PVY), and Tomato Spotted Wilt Virus (TSWV). Plant viruses are typically transmitted by insects, nematodes, or through contaminated seeds and tools. They infect plant cells disrupting their normal cellular functions and cause symptoms such as leaf curling, stunting, and mosaic patterns.

Explanation

Option (b) is correct: A transcriptome is the full range of messenger RNA(mRNA) molecules expressed by an organism. The term "transcriptome" can also be used to describe the array of mRNA transcripts produced in a particular cell or tissue type. Transcriptome analysis (RNA sequencing or RNA-Seq) is a key tool in bioinformatics for studying gene expression, identifying biomarkers, and understanding cellular functions.

Option (a), (c) and (d) are incorrect:

Genome editing involves enzymes like CRISPR-Cas9, TALENs, etc which are used to modify DNA sequences. These enzymes are tools for targeted genetic modifications. Transcriptome doesn’t relate to enzymes used in editing Gene expression involves the processes of transcription (DNA to mRNA) and translation (mRNA to proteins). It includes regulatory mechanisms like transcription factors, epigenetic modifications, and post-transcriptional processing. Mutations are changes in the DNA sequence caused by errors during replication, environmental factors, or chemical agents.