In competitive PCR, what is the role of the internal control DNA?
Answer: B
Competitive PCR uses an internal control (competitor) DNA that is amplified simultaneously with the target using the same primers, allowing relative quantification by comparing product amounts.
Q.42Hard
Which PCR variant is most suitable for detecting point mutations in genomic DNA?
Answer: B
ARMS-PCR uses allele-specific primers that only amplify when the primer sequence perfectly matches the target DNA, making it ideal for detecting specific point mutations.
Q.43Hard
In the context of DNA barcoding for species identification, which gene region is commonly used for plants?
Answer: B
For plant DNA barcoding, rbcL (ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit) and matK (maturase K) are the standard barcode regions recognized by CBOL.
Q.44Hard
In SNP genotyping using TaqMan chemistry, what is the function of MGB (Minor Groove Binder)?
Answer: B
MGB sequences bind in the minor groove of DNA, stabilizing the probe-DNA duplex and increasing its melting temperature, allowing for shorter, more specific probes.
Q.45Hard
Which DNA amplification technique is used to amplify sequences adjacent to a known sequence boundary?
Answer: B
Inverse PCR amplifies unknown DNA sequences flanking a known region by using outward-facing primers on a circularized DNA template, useful for genome walking and transposon mapping.
Advertisement
Q.46Hard
In droplet digital PCR (ddPCR), the sample is partitioned into thousands of micro-compartments. What is the primary advantage of this approach?
Answer: B
ddPCR partitions samples into independent reactions, allowing Poisson distribution analysis for absolute quantification without reference standards.
Q.47Hard
Which DNA technology would be most appropriate for detecting point mutations and SNPs in cancer genomics?
Answer: C
NGS and allele-specific digital PCR can detect rare mutations (ctDNA) with high sensitivity; RFLP/DGGE are less sensitive for point mutation detection.
Q.48Hard
What is the primary challenge in developing universal primers for metagenomic studies of microbial communities?
Answer: B
Universal primers (e.g., 16S rRNA) must accommodate sequence variations across taxa while maintaining specificity, creating a design dilemma.
Q.49Hard
Which modification to standard PCR allows amplification of extremely long DNA fragments (>3 kb)?
Answer: B
Long-range PCR requires thermostable polymerases with 3'→5' exonuclease activity (e.g., Pfu, Phusion) and extended elongation times for processivity.
Q.50Hard
Which PCR-based technique would be most suitable for detecting mutations associated with antibiotic resistance in Mycobacterium tuberculosis in clinical samples?
Answer: B
Allele-specific qPCR can rapidly detect known resistance mutations (e.g., rpoB in rifampicin resistance) in clinical TB samples for faster diagnosis.
Q.51Hard
In the amplification of GC-rich genomic regions, which strategy is most effective to reduce secondary structure formation?
Answer: B
GC-rich regions form hairpins; additives (DMSO/betaine) destabilize secondary structures, while higher denaturation temperatures and specialized polymerases enhance amplification.
Q.52Hard
A researcher is performing digital PCR (dPCR) for absolute quantification of mutant KRAS alleles in circulating tumor DNA (ctDNA). Compared to conventional qPCR, what is the primary advantage of dPCR in this application?
Answer: B
Digital PCR partitions samples into thousands of individual reactions, enabling absolute quantification without standard curves. This is crucial for detecting rare mutations where ctDNA comprises only 0.01-1% of total circulating DNA, making it superior for cancer diagnostics.
Q.53Hard
What is the primary limitation of primary cell cultures compared to continuous cell lines?
Answer: B
Primary cells have limited replicative lifespan due to the Hayflick limit and may undergo changes over passages, whereas continuous cell lines can divide indefinitely.
Q.54Hard
A researcher observes that their CHO (Chinese Hamster Ovary) cell culture shows reduced protein production despite maintaining normal cell density. What could be the most likely cause?
Answer: B
Even at normal density, cells require optimal osmolarity (280-320 mOsm/kg) and adequate nutrients. Nutrient depletion reduces metabolic activity and protein synthesis despite maintained cell count.
Q.55Hard
In the context of vaccine production using cell culture, which cell lines are most commonly used in India?
Answer: B
Vero (monkey kidney), CHO (hamster ovary), and HEK293 (human embryonic kidney) cells are widely used for vaccine production including COVID-19 and other vaccines in India.
Q.56Hard
Which of the following represents the correct sequence in scaling up cell culture from laboratory to industrial bioreactor?
Answer: A
Scale-up follows a logical progression from small (flask) to larger volumes, with each step validated for maintaining cell viability, growth rate, and product quality.
Q.57Hard
What is the significance of mycoplasma testing in cell culture quality control for biopharmaceutical production?
Answer: C
Mycoplasma is an obligatory contaminant in cell cultures that can affect cell behavior and product quality. Detection via PCR, culture, or ELISA is mandatory in biopharmaceutical manufacturing per ICH guidelines.
Q.58Hard
In a perfusion bioreactor system used for continuous cell culture, what is the primary advantage over batch culture?
Answer: B
Perfusion systems continuously exchange medium, removing metabolic wastes and supplying nutrients, enabling higher cell densities and prolonged culture periods compared to batch systems.
Q.59Hard
What is the significance of using antifoam agents in large-scale bioreactors?
Answer: B
Foam formation in bioreactors during aeration can cause cell lysis, loss of surface area, and carryover into exhaust lines. Antifoam agents (silicone-based) prevent this.
Q.60Hard
In the fed-batch culture strategy, the primary advantage over batch culture is:
Answer: B
Fed-batch feeding strategies prevent nutrient depletion and byproduct accumulation, extending productive culture phases and improving final product titers compared to batch culture.
