Q130. Membrane bioreactors are chiefly associated with which biotechnological application?
[UPSC CSE (Pre) 2024]
- (a) Drug delivery nanoparticles
- (b) Wastewater treatment
- (c) Vaccine inoculation
- (d) Embryo transfer
Answer: (b) Wastewater treatment
Explanation: A membrane bioreactor combines microbial biodegradation with filtration through a membrane. It treats sewage and other wastewater while retaining suspended solids and many microorganisms. Ordinary fermentation bioreactors have broader uses, but membrane bioreactors chiefly denote wastewater-treatment systems.
Q129. In a recombinant plasmid, the foreign DNA sequence is commonly called the:
[MPPSC — Practice]
- (a) Insert
- (b) Centromere
- (c) Ribosome
- (d) Cell membrane
Answer: (a) Insert
Explanation: The inserted DNA fragment is referred to as an insert, while the receiving DNA molecule is the vector backbone. The combination forms a recombinant construct. Confirming insert orientation and sequence is important before downstream gene-expression experiments.
Q128. Which microbial process involves uptake of free DNA from the surrounding environment?
[UPPCS — Practice]
- (a) Transcription
- (b) Translation
- (c) Respiration
- (d) Transformation
Answer: (d) Transformation
Explanation: Transformation occurs when a competent cell takes up DNA from its environment. Natural transformation happens in some bacteria, while laboratory procedures can induce competence artificially. Researchers use transformation to introduce recombinant plasmids for cloning or protein production.
Q127. Which technique introduces DNA into cells using short high-voltage electrical pulses?
[RAS / RPSC — Practice]
- (a) Dialysis
- (b) Autoclaving
- (c) Electroporation
- (d) Filtration
Answer: (c) Electroporation
Explanation: Electroporation briefly alters cell-membrane permeability through electrical pulses, enabling nucleic acids or other molecules to enter. It is used with bacteria and some eukaryotic cells. Cell viability and delivery efficiency depend on voltage, buffer and cell type.
Q126. What is the primary purpose of downstream processing in recombinant protein production?
[SSC CGL — Practice]
- (a) To select genes before cloning
- (b) To purify and formulate the required product
- (c) To destroy all cultured cells without recovering proteins
- (d) To sequence every genome in the environment
Answer: (b) To purify and formulate the required product
Explanation: After a recombinant protein is expressed, downstream processing separates it from cells, culture medium and impurities. Steps can involve filtration, chromatography and formulation. Purity, activity, sterility and stability are particularly important for medical products.
Q125. In genetic studies, microsatellite DNA is particularly useful for which purpose?
[UPSC CSE (Pre) 2023]
- (a) Comparing evolutionary relationships among animals
- (b) Testing drug effectiveness across patients
- (c) Turning stem cells into tissues
- (d) Clonal multiplication of fruit plants
Answer: (a) Comparing evolutionary relationships among animals
Explanation: Microsatellites are short tandem-repeat regions whose repeat numbers vary between individuals and populations. This variability supplies genetic markers for population studies, parentage analysis and evolutionary comparisons. Their standard use is not cell differentiation, tissue culture or clinical drug trials.
Q124. Which plant-associated bacterium supplies a widely used gene-transfer system for plants?
[SSC CHSL — Practice]
- (a) Mycobacterium leprae
- (b) Vibrio cholerae
- (c) Salmonella Typhi
- (d) Agrobacterium tumefaciens
Answer: (d) Agrobacterium tumefaciens
Explanation: Agrobacterium tumefaciens naturally transfers part of its Ti plasmid into plant cells, causing crown-gall disease. Scientists modify the system by removing disease-causing regions and introducing selected genes. It is therefore an important vector for plant transformation.
Q123. In plant genetic engineering, the term T-DNA refers to:
[SSC MTS — Practice]
- (a) A plant-specific amino acid
- (b) Only mitochondrial DNA
- (c) The portion of Ti plasmid DNA transferred into plant cells
- (d) Every transfer RNA molecule
Answer: (c) The portion of Ti plasmid DNA transferred into plant cells
Explanation: T-DNA is the transferred segment of the Agrobacterium Ti plasmid. In engineered systems it can carry selected genes into a plant genome. Border sequences help define the region delivered from the bacterium to the recipient plant.
Q122. What is the principal objective of the polymerase chain reaction (PCR)?
[RRB NTPC — Practice]
- (a) Translate proteins in a cell
- (b) Rapidly amplify a defined DNA region
- (c) Count red blood cells
- (d) Separate fats from milk
Answer: (b) Rapidly amplify a defined DNA region
Explanation: PCR repeatedly denatures DNA, anneals primers and extends new strands, producing many copies of a selected region. A thermostable DNA polymerase makes repeated heating possible. PCR supports diagnostics, forensics, cloning and genetic research.
Q121. What does the expression “aerial metagenomics” most directly describe?
[UPSC CSE (Pre) 2023]
- (a) Sampling DNA carried in environmental air
- (b) Taking blood samples using airborne drones
- (c) Collecting soil specimens through aircraft
- (d) Sequencing only the genes of birds
Answer: (a) Sampling DNA carried in environmental air
Explanation: Aerial metagenomics examines genetic material captured from airborne biological particles, including microbial cells, spores and environmental DNA. By analysing material collected in air filters, researchers can study biodiversity without directly sampling every organism present in the habitat.
