In cloning, which vector is most suitable for inserting large DNA fragments (>15 kb)?
Answer: B
Cosmids can accommodate DNA inserts of 35-45 kb, making them ideal for large DNA fragments compared to plasmids (5-20 kb).
Q.2Hard
The principle of AFLP (Amplified Fragment Length Polymorphism) combines:
Answer: A
AFLP integrates restriction enzyme digestion with selective PCR amplification of restriction fragments for genetic diversity analysis.
Q.3Hard
In gene editing, CRISPR-Cas9 uses which type of guide molecule?
Answer: B
CRISPR-Cas9 employs a single guide RNA (sgRNA) that directs Cas9 endonuclease to specific DNA target sequences for precise editing.
Q.4Hard
In forensic DNA analysis, STR (Short Tandem Repeat) profiling is preferred over SNPs because:
Answer: B
STRs (variable number tandem repeats) show higher allelic variation than SNPs, providing greater discrimination power for individual identification in forensic cases.
Q.5Hard
Which technique combines PCR with capillary electrophoresis for high-resolution DNA fragment analysis?
Answer: B
Microsatellite (STR) genotyping uses PCR followed by capillary electrophoresis for precise size determination of amplified fragments for forensic and population studies.
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Q.6Hard
In the context of 2024-25 genomic studies, what is the primary advantage of long-read sequencing technologies (PacBio, Oxford Nanopore) over short-read NGS?
Answer: C
Long-read sequencing can span repetitive sequences and detect large structural variations that short-reads cannot resolve, improving genome assembly quality.
Q.7Hard
What is the significance of the primer Tm (melting temperature) in multiplex PCR?
Answer: A
In multiplex PCR, all primers should have similar Tm values (within 1-2°C) to use a single annealing temperature, preventing preferential amplification of certain targets.
Q.8Hard
CRISPR-Cas12 (Cpf1) differs from Cas9 in that it:
Answer: B
Cas12 creates staggered cuts resulting in sticky ends, requires only one CRISPR RNA (not separate tracrRNA), and recognizes T-rich PAM sequences, offering advantages for some applications.
Q.9Hard
In environmental metagenomic studies using 16S/18S rRNA amplicon sequencing, what is the primary limitation?
Answer: B
While 16S/18S rRNA is excellent for community profiling, limited sequence divergence at species level makes species-level discrimination challenging, requiring shotgun metagenomics for finer resolution.
Q.10Hard
In somatic gene therapy using ex vivo approach, which cell type is most commonly targeted for genetic modification?
Answer: B
Hematopoietic stem cells are preferred because they can self-renew, are easily accessible via bone marrow/blood, and can be reinfused to establish long-term therapeutic effects for blood disorders.
Q.11Hard
Which DNA technology is most suitable for detecting chromosomal abnormalities like deletions and duplications at the genomic level?
Answer: A
Array-CGH (aCGH) provides high-resolution detection of chromosomal imbalances across the entire genome, making it ideal for identifying deletions and duplications.
Q.12Hard
When designing a TaqMan probe for qPCR, what is the relationship between probe length and specificity in target detection?
Answer: B
TaqMan probes of 18-25 bp with Tm 5-10°C higher than primers provide optimal specificity and sensitivity by requiring perfect base pairing for nuclease cleavage.
Q.13Hard
In forensic DNA analysis using STR markers, what advantage do newer SNP-based methods provide over traditional STR typing for 2024-25 investigations?
Answer: B
SNP-based methods offer lower mutation rates (~10⁻⁸), enable ancestry inference, and work better with degraded DNA samples compared to STRs, making them valuable for cold cases.
Q.14Hard
Which PCR-based technique is specifically used to amplify and sequence unknown DNA flanking regions of known sequences?
Answer: B
Inverse PCR uses outward-facing primers on a circularized DNA template to amplify and sequence flanking regions of known sequences, useful for finding regulatory elements.
Q.15Hard
In GWAS (Genome-Wide Association Studies) using DNA microarrays, what statistical principle is applied to identify significant SNP-trait associations?
Answer: A
GWAS uses Chi-square tests with Bonferroni correction (or FDR correction) to account for multiple hypothesis testing across millions of SNPs and identify genome-wide significant associations.
Q.16Hard
What is the primary principle of High-Resolution Melting (HRM) analysis in qPCR?
Answer: A
HRM analysis detects genetic variations by monitoring the melting temperature (Tm) of PCR products; sequence variations cause different Tm values, visible as distinct melting curves.
Q.17Hard
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.18Hard
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.19Hard
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.20Hard
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.
