The optimal annealing temperature in PCR is typically set based on:
Answer: C
Annealing temperature is determined by the Tm of primers, calculated using GC content and primer length formulas.
Q.2Medium
Which of the following is a limitation of conventional PCR?
Answer: C
Conventional PCR detects products only at the end. Real-time PCR (qPCR) monitors amplification during each cycle.
Q.3Medium
What is the primary advantage of real-time PCR (qPCR) over conventional PCR?
Answer: C
qPCR uses fluorescent dyes to monitor product accumulation in real-time, providing quantitative data.
Q.4Medium
Which type of restriction enzyme produces 'sticky ends'?
Answer: A
BamHI produces staggered cuts creating complementary single-stranded overhangs (sticky ends). Others like PvuII produce blunt ends.
Q.5Medium
In RAPD-PCR, the primers are:
Answer: B
RAPD (Random Amplified Polymorphic DNA) uses short, arbitrary primers that amplify random DNA regions, useful for molecular markers.
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Q.6Medium
Which technique is most suitable for detecting SNPs (Single Nucleotide Polymorphisms)?
Answer: B
RFLP (Restriction Fragment Length Polymorphism) can detect SNPs that create or eliminate restriction sites.
Q.7Medium
In DNA fingerprinting, which polymorphic markers are most commonly used in India?
Answer: B
Modern DNA fingerprinting in India uses STRs and SNPs for high discrimination power in forensics and paternity testing.
Q.8Medium
Which of the following is a common application of PCR in diagnostic medicine?
Answer: A
RT-PCR (Reverse Transcription PCR) is widely used in India and globally for COVID-19 diagnosis by detecting viral RNA.
Q.9Medium
What is the significance of dNTPs in PCR?
Answer: B
dNTPs (dATP, dGTP, dCTP, dTTP) serve as substrates for DNA polymerase to synthesize new DNA strands.
Q.10Medium
Real-time PCR differs from conventional PCR in that it:
Answer: B
Real-time or qPCR (quantitative PCR) monitors DNA amplification in real-time using fluorescent dyes (SYBR Green or TaqMan probes) to detect product accumulation during each cycle.
Q.11Medium
Which annealing temperature is most appropriate for primers with a GC content of 50%?
Answer: B
Annealing temperature is typically 3-5°C below the Tm (melting temperature). For 50% GC content, Tm ≈ 55-60°C, making this the appropriate annealing range.
Q.12Medium
In next-generation sequencing (NGS), what is the primary advantage of massively parallel sequencing over conventional Sanger sequencing?
Answer: A
NGS provides massively parallel sequencing, generating millions of reads simultaneously, offering significantly lower cost per base and much higher throughput compared to Sanger sequencing.
Q.13Medium
What is the purpose of using a 'hot start' Taq polymerase in PCR?
Answer: B
Hot start Taq polymerase is inactive at room temperature and becomes activated only at high temperatures (95°C), preventing unwanted non-specific amplification during setup.
Q.14Medium
In DNA barcoding for species identification, which gene region is most commonly used?
Answer: B
COI (cytochrome c oxidase I) is the standard DNA barcode for animal identification due to its high interspecific variation and low intraspecific variation.
Q.15Medium
Which of the following best describes the principle of digital PCR (dPCR)?
Answer: B
Digital PCR partitions the sample into thousands of individual reactions (droplets), allowing absolute quantification by counting positive and negative partitions without requiring standard curves.
Q.16Medium
In gene therapy, AAV (Adeno-associated virus) vectors are preferred because they:
Answer: B
AAVs are preferred due to minimal immunogenic response, ability to target specific tissues, and safe integration properties, despite a packaging limit of ~4.7 kb.
Q.17Medium
What is the principle behind site-directed mutagenesis using PCR?
Answer: B
Site-directed mutagenesis uses primers with mismatches at the desired mutation site. During PCR extension, the mutated sequence is copied, incorporating the specific change.
Q.18Medium
Which PCR variant is specifically designed for amplifying and detecting microRNA (miRNA) targets in clinical samples?
Answer: B
Stem-loop RT-PCR uses a stem-loop primer structure that specifically binds to mature miRNAs, making it ideal for miRNA detection and quantification in diagnostic applications.
Q.19Medium
In RAPD-PCR (Random Amplified Polymorphic DNA), what is the primary application in agricultural biotechnology?
Answer: A
RAPD-PCR uses random primers to generate DNA fingerprints for assessing genetic diversity, distinguishing crop varieties, and parentage analysis in breeding programs.
Q.20Medium
During DNA amplification using PCR, if the initial template has 2 copies, approximately how many copies will be present after 30 cycles (assuming 100% efficiency)?
Answer: C
PCR follows exponential amplification: Final copies = Initial copies × 2ⁿ, where n = number of cycles. 2 × 2³⁰ = 2 × 1.07 × 10⁹ ≈ 2 × 10⁹ copies.
